Dave Johnson

I’ve long been a fan of the work of Dave Johnson.  He has been the mind behind many, many popular metal detectors including; White’s MXT, Shadow X5, the Fisher CZ series, Teknetics T2, Fisher F75, etc., etc.

Dave not only designs great metal detectors, he also has a great sense of humor!  Some of that will  be apparent as you read through these posts.

Below is a collection of forum postings I’ve gathered from all over the place.  I give total credit to the owners of the boards where these were originally or in some cases, still exist.  IF any board wants me to remove material reprinted from your site, please let me know.  As far as the originating author goes (Dave Johnson), I have requested and graciously received his permission.

On some of these, I’ve included the original question or forum post that prompted a response from Mr. Johnson so that there is some context to the answer.  If any of the original posters are opposed to me printing your post here, let me know and I’ll fix it.

There is just too much “good stuff” in his posts for it to be overlooked or lost to time and temperamental web servers.


American Relic Hunters forum (now closed)

Metal Detecting Equipment forum

If you are a fan of Dave, check out his page of non-metal detecting essays HERE

What is Dave J. up to these days? (as of Dec. 27th, 2022) Check out his page at https://cojotruk.wordpress.com/


genuine fieldtest—
Posted by clark on 11/28/2010, 1:22 pm

a few weeks ago I decided to do a field test to see what difference(if any)that a multi freq. detector would have on finding deep targets–my friend and I chose this small sports field at a local school—we hunted it for several weeks until we had dug every signal that we could get–we used these detectors— whites 5900–fisher f5–goldbug se—troy x5—garrett 1000—whites 4db—tesoro silver umax–yesterday I took the MINELAB EXPLORER 2 and was shocked at the number of signals that I found—1 war nickel—2 wheat cent—11 pieces junk jewelry—1 small key—7 coat buttons—hard to believe—I always knew that the way that any metal detector “handles” the ground will determine what you will find—simple as that !

no such thing as a cleaned out site
Posted by Dave J. on 11/28/2010, 5:08 pm, in reply to “I guess it shows there’s not much point in buying an Exp 2?”

Can’t even clean it out with an LRL! (Sorry, couldn’t resist.)

* * * * *

Not to knock the Explorer, but if you were to go over a site like that with the Explorer until you stopped finding stuff, if you follow up with a good modern 13-19 kHz single-freaker you’re gonna find gobs of stuff the Explorer missed. And a lot of it won’t even be very deep, you’ll wonder how the Explorer could possibly have missed it.

Every detector has its strengths and weaknesses, and that’s why no beep can literally clean out a site.

Dankowski’s website has a superb piece of research on how how much stuff metal detectors miss because of iron masking.

–Dave J.

one thing that you might consider—
Posted by clark on 11/28/2010, 5:17 pm, in reply to “no such thing as a cleaned out site “

“I don’t sell or promote or make any money in any way fashion or form from metal detectors”
can you say the same?

your complaint was what?
Posted by Dave J. on 11/28/2010, 5:43 pm, in reply to “one thing that you might consider—“

Clark, I’ve been in the beep business for 30 years, which is why I’m able to make the informative posts that I do.

And if you read my post, I did not knock the Explorer. If you read my post on the Lobo ST earlier, I spoke well of it even though it is manufactured by a competitor. Most folks here have noticed that in posting on this forum, I’m not very partisan. If you want partisan, ask “Minelab Kevin” to start posting here.

The moderator in his wisdom does not prohibit people from posting who earn their living in the beep business. The fact that quite a few people who do earn their living in the world of beep is one of the things that makes this the special kind of forum that it is. And, if you swing beeps, surely you must be grateful that there are people who earn their living in this business!

Now back to your complaint…. what was it again?

–Dave J.

PS: if you know of a machine that’ll clean out a site leaving nothing for anyone else, get rid of all the others and use that one. And don’t forget to tell us what one it is!


I post my different opinions
Posted by clark on 11/28/2010, 7:08 pm, in reply to “your complaint was what?”

about what I have learned about detecting–I don’t make any money or write any books about detecting–I said it earlier and say it again–“you or anyone else can use it to your benifit or simply pitch it”
you have many years of designing detectors and have made probably tons of money doing so—you are a very smart man,much smarter than I am— but how much actual field experience do you have?–I should have known better than to compare one detector against the other–there will always be an agument about what is best–go ask a tesoro,whites,fisher or anyother dealer ,which detector has the best meter,best depth,best recovery–guess what the answer will be—you can never get an “un-bias” answer ! — I have been using detectors for well over 50 years and logged in many thousand hours of detecting—I’m well aware of the “MASKING” affect that detectors have—pay close atention to this next statement–” if the detectors that I used prior to using the explorer2 didn’t find the mentioned targets,then that proves that the explorer2 has not only better depth but is better at un-masking target, than the others”!–
“that’s my story and I’m sticking to it”

Re: I post my different opinions
Posted by Carl-NC on 11/28/2010, 7:42 pm, in reply to “I post my different opinions”

“and have made probably tons of money doing so”

Heh heh… if Dave is like me, he does what he does ’cause he enjoys it, and could be making better money elsewhere. But, as our dear ex-Prez once said, it “puts food on our family.”

– Carl


LRL locators ?????
Posted by clark on 11/26/2010, 11:00 am

do LRL locators really work—sure they do—do they work for everyone–the answer is no–why?—because not everyone really understands the principle behind the way that they work—will they lead you to treasure, again the answer is no—what they will do is ” convince you that there is treasure where you believed it to be”—so in essence, they are only an implement to bring out your enter thoughts !

not the first examiner to be bamboozled
Posted by Dave J. on 11/27/2010, 1:15 pm, in reply to “LRL locators ?????”

Why is the USPTO issuing patents on pseudoscience?


This LRL stuff has a history, and it ain’t pretty.

–Dave J.


patent examiner bamboozled!
Posted by Dave J. on 11/27/2010, 1:04 pm, in reply to “LRL locators ?????”

The things that the LRL advocates say, alone suffice to discredit them. Read the websites, read the ads, they tell the whole story right there. This is why I’ve never thought “double blind tests” etc. to be of much interest.

And then there’s patents. Here’s Christensen’s (of h3 fame) patent, issued this year:


It’s an elaborate snow job, read it for yourselves! Inexcusable that the examiner would have awarded such patent.

But at least Christensen doesn’t have to worry about infringers!

He loses sleep over Carl, but there’s no indication he loses sleep over what happens to people when those things are sold to military and police agencies.

–Dave J.


1. I’ve run into a few (perilously few) “honest dowsers” but those people are not selling LRL’s and don’t generally feel that they have anything to prove.

2. There are LRL manufacturers who (as far as I know) don’t market to police and military, being satified with fleecing gullible civilians. My favorite is the Gravitator, a very expensive adult toy for which the manufacturer makes no claims regarding its ability to do anything for the customer, nor even any claim that it’s an “LRL” (although I put it in that category).

* * * * *

Tnet’s downtime has certainly provided the metal detecting equipment forum an entertaining tangent of discussing non-detector detectors, but I look forward to Tnet’s resumption of normal operation so we can get back to discussing detectors that do detect.

Re: patent examiner bamboozled!
Posted by Carl-NC on 11/27/2010, 2:05 pm, in reply to “patent examiner bamboozled!”

“My favorite is the Gravitator,…”

The same guy who makes the Gravitator also makes the DKL Lifeguard, which is marketed to fire, rescue, and border enforcement groups. He also got a few pseudopatents, covered in the Rislove pdf.

– Carl


DKL cleverness
Posted by Dave J. on 11/27/2010, 4:58 pm, in reply to “Re: patent examiner bamboozled!”

Here’s the link to DKL:


Wow, what a difference from the utterly amateurish h3 website! The DKL site is very slick, does not bear all the obvious hallmarks of a con game, unlike the Gravitator ads it makes very specific representations regarding the performance of the device, ……..but darn, that “LifeGuard” sure bears a striking resemblance to the Gravitator for which (strangely enough) no performance claims at all are made!

Then there’s this other product, the SilentGuard. They say it’s based on the same sensing principle as the LifeGuard– detection of the electric field produced by the human heartbeat.

The news stories are mostly ambiguous about whether the thing actually located a person whose location was otherwise unknown, but a few of the stories are fairly explicit about locating persons whose location was otherwise unknown.

If a person didn’t have any knowledge of electronic detection technology, and did not have a lot of experience in spotting fraud, the thing could look quite plausible even to a reasonably skeptical person.

****** HERE’S THE REST OF THE STORY ********

Some of us out here are in the business of detecting low frequency electric and magnetic fields, and know about this stuff. But first, let’s deal with the dowsing question.

The LifeGuard is recognizeable as a very probable dowsing rod from the DKL website. If you’re already familiar with the Gravitator from the treasure mag advertisements, which is described in much more detail and the character of which is in plain view by using the brains God done guv ya, then doubt that the DKL might be something other than a dowsing rod is removed.

The SilentGuard is not a dowsing system: in fact the physical description of the thing bears no resemblance to the LifeGuard. The installation drawings look much like a straight VHF field leakage intrusion detection system having nothing to do with detecting heartbeats and having no discrimination between humans and large animals. So– is the thing entirely bogus, or is it a VHF field leakage perimeter intrusion detection system advertised as something entirely different? Gee, if it’s a working VHF field leakage system why not just be honest and say so? No matter how you cut it, something’s very fishy about the thing.


The human heart does produce electric field potentials. That’s what an EKG measures. The signals are pretty weak. An EKG makes physical contact with the human body a couple inches or so away from the heart. Making physical contact reduces the impedance to a few hundred ohms making it possible to reduce the thermal noise level and to reduce pickup from external ULF electric fields which are (because of transmission through the air) extremely high impedance.

Under carefully controlled electrostatically shielded laboratory conditions it would probably be possible to construct an apparatus which could detect the electric field of a heartbeat from quite a few feet away. If you’re a very good engineer, and I do mean VERY good. It wouldn’t look anything like the LifeGuard because, well…. that’s not what the LifeGuard is designed to do.

Even without the swivel, an apparatus that looks anything like the Gravitator, no matter how well engineered, is not going to detect the electric field of a target subject heartbeat from 500 meters away– probably not from 1 meter away. Under open field conditions there is fairly high amplitude ULF electric field interference from sferics and atmospheric turbulence, as well as from leaves rustling in the breeze, movement of clothing, movement of nearby vehicles and people and animals, flying insects, ordinary low frequency interference from power distribution systems, rectification of radio signals in nonlinear contacts of metallic conduits and wires, solar storms, the list is almost endless.

DKL claims detection of hearbeat ULF electric fields through shipping containers, which are metal and which provide superb ULF shielding. At least they don’t claim the full 500 meters for this miracle.

I have designed and used ULF electric field apparatus (Fisher PF-18 sheath fault locator) in the same frequency range (

“Extraordinary claims demand extraordinary evidence”. The DKL website offers no evidence whatsoever that there is any science behind their claims, none that I could find anyhow. I challenge anyone else to do better.

If they’d have said, “Look, the thing works by ideomotor response, can’t you see the handgrip and swivel?” then they could be believed. The issue would not be whether the gizmo works, it would be whether the ideomotor is tuned up and running on all eight cylinders, a matter for which the manufacturer bears no responsibility.

–Dave J.

Warning! Using The Deekle LifeGuard could kill you!
Posted by Dave J. on 11/28/2010, 12:35 pm, in reply to “DKL cleverness”

This thing is hand-held, and detects heartbeats at 500 meters, right?

Meanwhile you’re holding this thing less than a meter from your heart. In order for it to detect the target person, you have to learn the art of willing yourself into cardiac arrest.

Good luck trying to will yourself back out of it, because you’re gonna lose consciousness in several seconds.

Shame on me for not realizing this in yesterday’s post!

–Dave J.


follow the money, this is amazing!
Posted by Dave J. on 11/27/2010, 12:05 pm, in reply to “LRL locators ?????”


interesting link
Posted by Tom_in_CA on 11/28/2010, 5:28 pm, in reply to “follow the money, this is amazing!”

That is a very interesting read. Thanx.

But did you catch the contradictions? The vast majority of the link, seems to indicate that it’s worthless fraud, non-scientific, etc..

However, workable success with the instrument has been, and is, being reported! Here is one such quote:

“He told a press conference that the ADE 651 has detected “hundreds of roadside bombs and car bombs” and any deficiencies were due to defective training in the device’s use.[16] The Iraqi Interior Minister, Jawad al-Bulani, also defended the device, telling Al Iraqiya television that the ADE 651 had “managed to prevent and detect more than 16,000 bombs that would be a threat to people’s life and more than 733 car bombs were defused”

You see there? That dispells all the snake-oil allegations, right? I mean, you can’t argue with success, right? And for anywhere else in the link, which pointed to supposed failures of the device to work, well look closely to what I’ve cut & pasted: It merely means the persons who failed to get the responses, weren’t adequately trained, and weren’t using the device right! Wooohoo!

You can’t argue with this, right? It’s bullet-proof logic!

Not the only statement out of Iraq
Posted by Dave J. on 11/28/2010, 6:00 pm, in reply to “interesting link”

That there are people who report success with LRL’s isn’t exactly news. Usually there’s no way to independently verify the report and in some cases self-delusion or intent to deceive others can be specifically identified in the report. For example, in Iraq there are officials who regard LRL’s as fraudulent and therefore dangerous. When terrorists know checkpoints are being scanned with LRL’s, of course those are the checkpoints they’re going to drive bombs through!

* * * * *

I say the best way to understand what an LRL is, is to study the information that comes from the manufacturer. That settles the matter right there. I call it “read the advertisement”.

Therefore, no need for testimonials from outside sources favorable or otherwise, no need for double blind testing by an independent agency, no need for statements from government officials, none of that stuff is needed. When you’ve “read the advertisement” you already know what it is.

–Dave J.

Re: Not the only statement out of Iraq
Posted by Tom_in_CA on 11/29/2010, 9:41 am, in reply to “Not the only statement out of Iraq”

Dave, you say:

“That there are people who report success with LRL’s isn’t exactly news.”

Are you saying these people are liars then?

Let’s, for the moment, take out the possible portion of those whose “intent [is] to deceive others” (that is … faked testimonies from those with vested money interests, that can’t really be included as “testimonies”). Let’s, for the moment, include only those “testimonies” that are from folks who have actually found bombs or drugs with the device. Are you saying that THOSE testimonies don’t exist?

To the contrary, I’ll bet that there have been successes. This has been seen in other such devices that got used in law enforcement. I recall one such device that …… when word circulated back to a few USA police dept’s that they’d been duped, it was a SURPRISE to them, because they had, in fact, been using the devices with some success! And it appeared to more than random chance (ie.: there WAS actual successes they were reporting). So to them (those with no vested financial interests), this was a surprise to them, when someone else came along telling them it was a form of dowsing. They simply could not believe it, and proceded to point to their successes to defend it.

Are you saying these people are lying, or deluded?

Like, take for the example the quote I took from your link: Do you think that was made up (ie.: lies)?

This is one of the big problems I have when debating a LRL advocate, back when I took a few stabs on an LRL forum: they will invariably point to success (jar of coins or whatever), and ………. assuming they’re not lying, then the doubter is left to dance around trying to explain this success.

So you are either saying they’re lying, or that their “find” was d/t random chance?

Re: Not the only statement out of Iraq
Posted by Dave J. on 11/29/2010, 11:54 am, in reply to “Re: Not the only statement out of Iraq”

I guess I don’t understand your question. Of course some LRL users and advocates are liars. Of course some are deluded.

Maybe a few can actually dowse. However to my knowledge no manufacturer of LRL’s says that the basis for their successful use (if any) is dowsing.

–Dave J.

Re: Not the only statement out of Iraq
Posted by Tom_in_CA on 11/29/2010, 1:40 pm, in reply to “Re: Not the only statement out of Iraq”

ok, so you acknowledge that some treasure (or drug or bomb)LRL’rs may actually have success. You agree that they are not 1) lying, and 2) deluded. Ok.

Then you would agree they work sometimes. Sure, you would say it’s working via mystical dowsing, and sure, they would disagree, but none-the-less, you would agree, it works for those “with the gift” or those “who have practiced and are doing it right” etc..

Then if all this is the case, then the issue is no longer “does it work?”, but rather “what is the source of the successes a few people seem to have?” And if it’s dowsing (as you allege), then presto, problem solved: You can’t assail their proposal that more practicing and experience might eventually make it work for each individual user. Afterall, you’ve already admitted that it works for some, and perhaps those “some”, are people who practice and learn to use it correctly.

And Dave, how do you handle this: You’ve already admitted in previous posts of yours, that things like demonstrating this, in double-blind staged tests, is in order (like for the patent office, as one of their criteria, etc…). Now let’s say, for instance, that a person comes forward, and does indeed show success (let’s just say, since you acknowledge it works for some). And now, along comes Dave, and “well I explain this success to dowsing, not the science of their supposed electronics inside the wand”. And then you are left trying to reverse engineer it, to show that the circuits lead nowhere, and the jargon doesn’t hold water, etc… right? But wait: the proponent merely has to tell you that it’s “undiscovered science”. Ie.: yes, perhaps you or him can’t fully explain or debunks it by currently existing principles, but …….. afterall, the history of science is FILLED with things that got re-adjusted, explained, etc… later on (eg.: science at one time said man could never fly, or that the earth was flat, etc…).

So when someone demonstrates that this device can work (as you admit that for some people it can), they can tell you it’s not dowsing, and that it’s totally scientific (but as yet, not-understood science). How can you argue with that? Afterall, if they’ve demonstrated that it works, then it’s just your word against there, that whether it’s grounded in something scientific (as yet un-discovered), or whether it’s mystical magic supernatural stuff.

no time for that
Posted by Dave J. on 11/29/2010, 1:59 pm, in reply to “Re: Not the only statement out of Iraq”

Tom, you’re putting words in my mouth and attributing opinions to me that are not mine. Furthermore you expect me to validate purported “science” which is on the face of it a con game or outright ignorance, not secret sauce that nobody understands but the inventor.

If you wish to hear the kinds of stuff that LRL proponents love to dish out, I’m not your man. I suggest diving into the Tnet LRL forum when it’s back on line and you’ll hear enough to make your head spin.

–Dave J.

T’net LRL forum
Posted by Tom_in_CA on 11/29/2010, 2:25 pm, in reply to “no time for that”

Been there, done that. This is where I’m getting all the come-back lines that I’m “trying out on you” here. Want to see how a skeptic can properly respond.

So how do you respond to the “un-discovered science” line they give? On the surface, when you’re faced with success stories (which you admit exists, on this thread), it seems like the answer to the engineer, is to de-bunk the machine by reverses engineering it, and showing that it violates scientific laws. Thus, the skeptic concludes “the success therefore has to be d/t dowsing, not science”.

But if they come back with the “un-discovered science” line, a lot of people are swayed by that. The LRL’r will say “afterall, scientists once thought the earth was flat”, etc… Thus, LRLs they make are “un-discovered science, and nothing to do with dowsing”. Afterall, you can’t argue with success, right?

To attribute some successes to dowsing, might …… afterall …. seem to lend credence to some sort of mystical powers, supernatural, etc… and that borders on religion, spiritual, magic, etc… And we certainly can’t include those things in the discussion, if the “here and now” is all there is, right?

Posted by Dave J. on 11/29/2010, 8:30 pm, in reply to “T’net LRL forum”

Since this is rather off-topic for this forum, I’ll try to keep it as brief as possible while providing a reasonably complete response.

I offer two explanations for successful dowsing.

1. That based on the bringing out of the subconscious, knowledge which has its origin in past experience and present environmental clues. I presume most “dowsing skeptics” accept this principle of dowsing, since it’s pretty much common sense.

2. That based on bringing out of the subconscious, knowledge the origin of which cannot be explained by #1. This of course is hotly disputed.

I acknowledge #2 because I have experienced it in blinded dowsing (the only kind of dowsing I’m interested in doing) and have also experienced other paranormal phenomena which have no satisfactory explanation. These were personal experiences which prove nothing to anyone else, so there is no need for me to describe them. Many people have had “paranormal” experiences, no big deal there either.

I suppose that most diehard skeptics would acknowledge that in principle, there may be ways for information to get into the subconscious which are not yet understood: after all we have not exhausted Mother Nature’s list of surprises. The showstopper from the uber-skeptic point of view is the results of double-blind tests of paranormal performance (esp. dowsing) which consistently show results no better than chance.

This result has the “true believers” in an uproar, claiming the skeptics are somehow ripping them off. But that’s not where the problem is! The problem is that mental concern over success in the test is ruinous to the ability of the subconscious to come to the surface through ideomotor response. In plain English, the dowser loses the ability to dowse. Same principle as “performance anxiety” in the bedroom, the rod points just fine until the stakes are raised to pass/fail, then it wilts.

In the past I have speculated that there may be other more mysterious factors involved in failure under blinded test conditions, linked to the mysterious nature of blinded dowsing itself. However the plain English explanation above meets the Occam’s Razor test so I’ll say it suffices for now.

* * * *
And there you have a reasonably complete theory of dowsing, which accounts for what dowsers report as well as what skeptics report. I have no great ideas how to “prove” the theory to everyone’s satisfaction, but even a skeptic should be able to regard it as plausible. I don’t know of any other theory of dowsing which accounts for so much which has comparable plausibility.

–Dave J.

Posted by Tom_in_CA on 11/30/2010, 1:06 pm, in reply to “dowsing?”

Let me see if I understand you correctly: the successes of some dowsers (which you admit might account for some finds of LRL’s) are explained by:

1) ” …. bringing out of the subconscious, knowledge which has its origin in past experience and present environmental clues.”

Well gee, to that I would say, that this is no different than an md’r, or gold panner, or anyone else who goes out to look for something, and is merely using their know-how, of the “best likely spots”. Sheesk, I can do this too: I research out where an old country picnic site used to supposedly be. I arrive at the site, detector-in-hand, and survey the landscape. Where am I most likely to start? At the places where I most-likely think people congregated, and thus lost coins. Doh! Does that mean I was “dowsing”? So therefore, does the dowser really need the wands or coat-hangers to begin with, if all he is doing is just: “bringing out of the subconscious, knowledge which has its origin in past experience and present environmental clues”?

2) The rest of it, which can’t be attributed to #1, is perhaps “paranormal”. I would agree (because, I mean, how else to explain it, if it has no roots in anything electronic or scientific, yet seems beyond the pale of simple intuition, environment, experience, etc…?

To this I would say that a lot of the LRL people want to distance themselves from. Because to “go there”, has inherent problems. Because once you “go there” to that explanation, well then heck, what’s to stop you from also using ouji boards? tarot cards? crystal balls? incantations and spells? etc…. You are merely accepting, in some form or fashion, some sort of spiritual beyond-the-here-&-now, that can aid you in finding things, through certain mediums. And you can see, that a lot of people don’t want that label, as they enter into an arena of …. well …. you know. Thus, the desire of the LRL’rs to either go with your explanation #1, or stick with the scientific explanation (albeit perhaps “future” science )

other forums
Posted by Dave J. on 11/29/2010, 3:19 pm, in reply to “T’net LRL forum”

At last check Tnet isn’t back up yet. You might try Carl-NC’s Geotech forum, where some of the LRL action has recently migrated.

–Dave J.

As I said…….
Posted by Tom_in_CA on 11/29/2010, 3:57 pm, in reply to “other forums”

As I said already, I’ve spent countless hours there. I’m trying …… here ….. to get your take, on the subject of their seemingly bullet-proof line.

Re: As I said…….
Posted by Dave J. on 11/29/2010, 4:54 pm, in reply to “As I said…….”

Their line is basically “all BS is created equal and is indistinguishable from factual information which after all is always subject to revision and interpretation. Therefore it’s my word against yours, and mine’s right, and you cain’t prove nuthin!”.

You can’t help them because they already have what they want, which is to be in complete control of their imaginary reality, unthreatened by the Universe’s reality. From their perspective it’s a bullet-proof line, just as you say. Don’t be suckered by it! Let them be bulletproof, you don’t need such false security yourself. As the book of Proverbs says, “Fear of the LORD is the beginning of all wisdom.” Life lived as alive is personal insecurity, because we do not control what reality is, all we can do is to discover and respond to reality as best we can. Its decrees are marvelous and humbling to behold.

What I advocate is a ruthlessly scientific worldview, wanting to know the truth and practicing the disciplines of not wanting to fall victim to delusion. Of course everyone makes their own choice in this matter.

As is the case with all mortals, the Universe’s reality will eventually intrude on self-centered delusional worldviews and put them out of commission. Thus does the Universe Itself offer “the cure”.

* * * * *

To put it all in another way, the “read the advertisement” principle which can be used to find out what an LRL manufacturer regards as its strategy for managing its Big Problem, can also be applied to a nonsense-blathering LRL apologist. The things they say advertise what their strategy is for managing their Big Problem. It’s a problem not within your power to fix, so don’t worry about it. Mother Nature will fix it in her own inimitable way.

–Dave J.

Here’s what I tried:
Posted by Tom_in_CA on 11/29/2010, 5:09 pm, in reply to “Re: As I said…….”

When I faced this “future science” line, I decided to try the same line, back on them, with an imaginary device. I told the few fellows I was wrangling with:

“If I were to take a tennis shoe, spread peanut butter on it, throw it up in the air, and figure that wherever it pointed, was the direction of treasure, what would you say to me?”

I got one of them to smell where I was going with this, so he tried to nip this illistration in the bud, by saying “the tennis shoe is not conductive”. To which I nipped him back in the bud, and told him “ah yea, but that’s the amazing thing about my tennis shoe invention, is that it’s scientific, but AS YET UN-DISCOVERED science”. I got a few of them to tell me my tennis shoe LRL was gibberish, and hopefully …… showed them they “can’t have it both ways”.

they get what they want
Posted by Dave J. on 11/29/2010, 5:25 pm, in reply to “Here’s what I tried:”

They’ve got a system where they can have it any way they want. In this system, reason and evidence are irrelevant.

You see the same principle with their alabi systems. Not only do they never have a bad dowse, it’s not even a dowse! They never screw up: anything that goes wrong is the fault of someone or something else.

Tom, you see it all as a problem needing fixed, but they see the same thing as their salvation from insecurity. You can’t fix it, so don’t worry about. Ignoring the wounded whom you cannot do anything for anyhow, is a basic principle of triage.

–Dave J.

Re: LRL locators ?????
Posted by Paul (Ca) on 11/26/2010, 12:27 pm, in reply to “LRL locators ?????”

About a year ago, Someone was selling his late fathers Compass metal detector equipment as a package deal. The son did not want to sell the equipment separate, his asking price was a little more than what I had wanted to pay but non the less fair enough considering all the extras it came with one of the extras an LRL (Lectra Search X-60A) locator.

I’ve ever tried it, Still sits in it’s carry hand bag. Mint condition too, Still has the owners manual and hip mount pouch.

One of the days, I’ll give her a try.

Paul (Ca)

Posted by Dave J. on 11/26/2010, 1:13 pm, in reply to “Re: LRL locators ?????”

Looks like it’s got a good swivel. If you believe it won’t work without a battery, don’t forget to install the battery.

–Dave J.

Signal amplification
Posted by willy on 11/26/2010, 11:10 pm, in reply to “Lectra-Search”

My buddy Jim (R.I.P.) once met a guy with a ‘witching wand’, looking for gold, who had a transistor glued to the end of his dowsing stick. Said that ‘it amplified the signal’. Maybe he was one of the early field testers. Go figure. ..Wily.

Re: Signal amplification
Posted by Dave J. on 11/27/2010, 5:13 pm, in reply to “Signal amplification”

An octal socket vacuum tube would have been more impressive.

–Dave J.

Anyone Else Having Issues Getting On To Treasurenet?
Posted by John-Edmonton on 11/22/2010, 2:45 pm

It’s been down for about 3 days.

This guy is claiming responsibility…
Posted by Carl-NC on 11/23/2010, 3:35 pm, in reply to “Anyone Else Having Issues Getting On To Treasurenet?”

Chuck Christensen of H3Tec, who sells $10,000 LRLs, is claiming responsibility for bringing TNet down:


Whites Should Check on This
Posted by prospector on 11/25/2010, 1:19 pm, in reply to “This guy is claiming responsibility…”

I think Carl Moreland should devote his time to improving the Whites line of detectors and keeping that line vibrant for years to come. It seems he spends an inordinate amount of time messing with these LRL characters. How could one devote so much time arguing with the various characters of Sam and still keep on the cutting edge of detector technology? Carl is an extremely talented engineer but he seems to be wasting important resources. A quick check of his post history shows he is continually involved in the remote sensing forums rather than real treasure hunting. At this rate First Texas will continue to expand it’s market base…

leave the worrying to others
Posted by Dave J. on 11/25/2010, 3:34 pm, in reply to “Whites Should Check on This”

Prospector, we all have things that we do as outside interests, besides our “work”. Carl had a deep interest in geophysics and LRL/dowsing stuff long before he went to work for White’s. I probably spend a lot more time working to find effective treatments for Lou Gehrig’s Disease, than Carl does on LRL forums. First Texas-Fisher is still developing new products despite that.

This h3 outfit appears to be infringing the trademarks of two metal detector companies, and that makes it business-related. What’s more, on their website they say they’re threatening Tnet, a popular metal detecting website. Which also makes it business-related.

Carl loves beepers, that’s why he went to work for White’s, hiring him is one of the smartest things White’s has ever done (wish we’d have thought of it first!). I think you can safely assume he’s doing a good job there, and leave the worrying up to guys like me who have to compete with him.

–Dave J.

Re: leave the worrying to others
Posted by prospector on 11/27/2010, 1:20 pm, in reply to “leave the worrying to others”

OK Dave, thanks. But given how my F75 and new Fisher gold machine work they better get in gear, Your machines rock!

engineering dept. always has new stuff under development
Posted by Dave J. on 11/27/2010, 1:39 pm, in reply to “Re: leave the worrying to others”

I suspect that for a long time to come, FTP-Fisher and White’s will still be competing with each other.

–Dave J.
“read the advertisement”
Posted by Dave J. on 11/24/2010, 1:45 am, in reply to “Solution to find out if it works”

Anyone who wonders what’s going on here needs to click on the h3 link and read it for themselves. With yer reasoning abilities intact.

I say, it’s a truer confession than that “love letter” the orange juice guy wrote to his murdered wife in LA a few years ago, that his lawyer read on TV hoping to vindicate him in the public eye. By sheer chance, two of my eyes were among those. Oddly, the “love letter” showed no anger toward the murderer, whoever that was…. whoever that was…. whoever that was… etc. …I’m gladly divorced, but if someone were to murder my daughter’s mother, I’d be looking to hang the cuss whodunit. The orange juice guy couldn’t go there.

I was most active on the Tnet LRL forum during 2002, which I don’t think is archived, sorry. Old timers may remember that Carl and I have some disagreements over whether dowsing may have some poorly understood forces behind it. But, I think) Carl and I agree that handheld LRL-type apparatus (regardless of whether the manufacturer calls it that or not) is moved by ideomotor response coming from a human brain (not from the target object). And that the fundamental difference between a pair of bent coathangers and an “electronic LRL” (usually claiming some sort of molecular frequency that can’t be found in any physics book on the planet) is how much the customer is willing to pay to deny that they’re doing that old fuddy-duddy dowsing stuff. ….Another point of disagreement between Carl and myself is whether or not people should be allowed to pay for the luxury of denial. I say plenty, “Darwin’s Law”, but intelligent minds can and do differ.

* * * * *

I have a bit of experience with dowsing myself, both successfully and unsuccessfully, and in my opinion based on that personal experience, something funny is going on. (My last experience was a solid blinded dowse of underground utilities, seemingly vindicated by unblinded visual evidence immediately afterwards, which was subsequently proved wrong by real electronic utility locating apparatus of the sort I’m well known for. The bad blinded dowse was solid…. interesting piece of evidence of something !) ….At Fisher we’re in the underground utility locating business, and that puts us in contact with end users who have to locate buried utilities, not just manufacture stuff like we do. And among people in the actual locating business, dowsing is very common, not because they have a philosophical axe to grind, but because they have found it to be useful. They use coathangers and occasionally something with a better swivel than a mere coathanger. Never the “electronic” LRL type stuff. They’d regard such stuff as an insult to their intelligence.

Dowsing is some sort of majick, and trying to add electronic geewhizzness to it is obviously snake oil merchandising. To the utility locating guys, just as much as to beep engineers.


–Dave J.


h3’s website and attacks reveal an interesting fact: they don’t believe their stuff works! Heck, even I would give it more credit than that. But if everything they say and do indicates they believe their stuff is worthless, better that you should listen to them than to me. If you feel inclined to listen to me, start with two bent coathangers and see for yourself what results you get or don’t get, while keeping your thinking cap firmly atop your head.

–Dave J.

Re: “read the advertisement”
Posted by Carl-NC on 11/24/2010, 2:18 am, in reply to “”read the advertisement””

“Another point of disagreement between Carl and myself is whether or not people should be allowed to pay for the luxury of denial.”

Generally, I’m fine with folks paying for “learning opportunities,” as long as the cost isn’t too high. Ferinstance, the Bernie Madoff Investment Fund was a bit costly. I got into this when I visited a neighbor who was hunting for a treasure and had sunk over $40,000 into LRLs… basically all his life savings. No matter what I said, he was still convinced they work. He paid a high price.

As you say, the best way to show the folly of LRLs is to let the manufacturers show you. I like to suggest an objective test of the device, with them behind the wheel, and watch ’em duck and run. At that point, folks who want to deny the ducking and running should seize the “learning opportunity” and buy the LRL.

– Carl

Re: “read the advertisement”
Posted by Dave J. on 11/24/2010, 3:23 am, in reply to “Re: “read the advertisement””

My argument is that there is no need for the Carl-NC (or Amazing Randi or whatever) challenge, just read the advertisement itself and that alone will tell you what the seller believes the device will or will not do– reading between the lines of course, as in the rest of real life. If real life isn’t what the customer wants, then they’ll pay for the alternative, and such is the free market.

But 40 grand is too much for an LRL, Carl, I’m with ya on that. What’s the highest price you can pay for a big-screen home television? Since TV is civilization’s greatest dumbing-down product, the top dog dumbster price tag would be an appropriate standard by which to judge the LRL’s. I wouldn’t want spending money on an LRL to make anyone dumber than spending the same amount of money on a television.

–Dave J.

Posted by BobD on 11/18/2010, 5:43 am

Who or what changed the ergonomics of metal detectors from the old curly
handle to the forearm-braced type that we use today?

Re: Fisher M-Scope Metalert Model 70
Posted by Dave J. on 11/19/2010, 5:51 pm, in reply to “Fisher M-Scope Metalert Model 70”

That’s one of the early “arm rest” + “grip mount electronics” on a straight pole that I had in mind. Ergonomically it was a lot better than the U-handle design, but not in the same league as the 1260-X.

I wasn’t aware that it had won a design award. Thanks for the post.

–Dave J.

Metrotech, wood
Posted by Dave J. on 11/20/2010, 11:58 am, in reply to “Re: Fisher M-Scope Metalert Model 70”

Metrotech was founded by some Fisher employees who decided to go do their own thing. They still make a 1970’s style TR for industrial valve & box locating.

On one of those units Paul posted a photo of you see what looks like a wooden handle. It really is wood– I believe walnut, which is fairly tough. Back in those days wood was often used in ways that nowadays we’d use plastic because the tooling cost for wood was low and it was easy to find people who knew how to work wood. Those old fashioned flat searchcoils (often with rubber seals around the edge) were usually made from plywood.

Back in the “olden days” you also see a lot of metal used in construction in places where nowadays you’d usually see plastic. Again, tooling costs for sheet metal are fairly low and in many cases the aluminum boxes could be purchased already made. White’s got big enough to bring under its own roof a very sophisticated metalworking operation including aluminum welding and powder coat “painting”: their skill and capital investment in metal fabrication is one reason why they tend to prefer metal wherever it still makes sense.

Injection molded plastic was and still is expensive to tool up for, although the pieces that come out of the mold are cheap. …..Ya gotta remember that back then metal detector manufacturing companies were small, often little more than a garage operation (and sometimes literally that) with low production volumes so there wasn’t much money available for plastic tooling.

–Dave J.

F75 All Metal
Posted by BamaBill on 11/17/2010, 6:15 pm

Is the All Metal on an F75 a true all metal? I’ve seen people talking about running in all metal and still having a number readout.

Posted by Dave J. on 11/19/2010, 8:43 am, in reply to “F75 All Metal”

Nearly all of FTP-Fisher’s newer products that have a ground balanced all metals mode, have visual target ID in that mode. (I can’t think of any exceptions off the top of my head, but ain’t had my morning coffee yet.) In most cases you get both a numeric readout and “speedometer scale”. With the new G2/GoldBug platform, it’s just the speedometer scale in all metals mode, the big number is used for reading the ground conditions.

–Dave J.

Hey Dave J.; Question about Bounty Hunter detectors..
Posted by willy on 11/15/2010, 2:29 pm

Hey there Dave.
Seeing as you’re a big Kahuna at First Texas and probably know a lot of closely guarded ‘secrets’.. one thing I’ve never really conclusively found out is whether the BH detectors, such as the tracker series and (in my case) Fortune Hunter, actually have ground tracking.. or is it a preset? Would be nice if such inexpensive detectors had such a feature. ..Willy.

Re: Hey Dave J.; Question about Bounty Hunter detectors.. – John Tomlinson, CET 11/16/2010, 8:39 am
MXT vs BH – Dave J. 11/16/2010, 1:45 pm
“tracking” – Dave J. 11/15/2010, 4:51 pm
Re: “tracking” – willy 11/15/2010, 5:26 pm
Re: “tracking” – Dave J. 11/15/2010, 7:23 pm
Re: “tracking” – willy 11/17/2010, 12:41 am
« Back to thread

The word “tracking” has been used in several different ways over the years in this industry, causing some confusion. The sales lit doesn’t necessarily clarify things.

In the early 1980’s, two different approaches to “ground tracking” were developed.

One method is to take the manual ground balancing principle (phase adjustment) and to automate it. This was relevant primarily to operation in all metals mode. The early systems weren’t very good, and I know of a couple of ’em that had fundamental engineering flaws that basically rendered them useless. Some phase tracking nowadays are pretty good. They have been partially supplanted by “ground grab” which more or less instantaneously ground balances at the push of a button, but does not “track” and therefore is not thrown off by targets.

The other system uses differentiation with high-speed retuning feedback in order to track out ground signals without adjusting phase (i.e. the phase is preset). This approach is of limited usefulness for all metals operation, but has proved very useful in discriminator design. The first commercial metal detector to use this principle was the Fisher 1260-X, but several companies got the same idea at about the same time and it became pretty much the standard way to build a continuous-time motion discriminator. Most sampled discriminators (with target ID) were adapations of the system.

None of our present products uses phase based ground tracking, as we have preferred manual and “grab” phase adjustment systems for those products which have phase adjustment.

Many of our products, from the under-$100 BH Junior to the F75, have discriminators which use differentiation to track out ground. In the case of our higher end models which offer phase adjustment, most augment the discriminator with the ground balanced signal as well.

In most ground conditions, if you’re searching in discrimination mode, phase adjustment has little impact on performance.

And, knowing how forums are, someone will probably want to argue with me that phase adjustment makes a big difference in discriminator performance. In MOST ground, it doesn’t, this is consistent with theory and it is what users report. If someone’s got an exception, well, it’s an exception.

–Dave J.
Differentiation between present signal and signal several tens of milliseconds prior. It’s done in two stages with a total delay typically between 50 and 100 milliseconds. This is orders of magnitude faster than phase tracking, but qualitatively it’s a completely different animal.

Your BH is an inexpensive coinshooting unit, not something to be compared with an MXT or Infinium for gold prospecting.

-Dave J.

Re: Metalic halo’s in soil
Posted by Dave J. on 11/15/2010, 12:41 am, in reply to “Metalic halo’s in soil”
Metallic particles are not transferred to the surrounding soil in metallic form other than the obvious, that remnants of a disintegrating metal object may be moved by bioturbation, vertisol churning, freeze-thaw, gravity driven slope creep, and other soil movement mechanisms. The result is of course far less detectable than the original metal object.

What happens to corroding metal, is that it is ionized by soil acids and converted to nonmetallic compounds. [Compounds other than soil acids may also be involved, but acids are the biggie especially if sulfur is also present.]

One can take samples of these metal element containing compounds, and in isolation verify that their electromagnetic characteristics are different from other compounds. However other than in the case of iron being altered to maghemite or rarely lepidocrocite (which have high magnetic susceptibility), the properties of the altered metal compounds are too weak to be detected in situ by a metal detector because of their small mass and their distance, relative to the soil bulk and its electrical and magnetic properties.

–Dave J.
Chief Designer, FTP-Fisher

My favorite example of bioturbation was in a “test bed” of metal targets I’d planted in northern Arizona. One target was a standard carpentry nail 6 inches deep– close to the limit of detection in discrimination mode in that particular (weathered basaltic) soil. One day I came testing metal detector prototypes and couldn’t find the nail. Since it was a marginal target anyway, at first I suspected a problem with the prototypes or with my technique. But all metals mode verified that the nail was not as it had been prior. I started digging and found that a gopher had tunneled through, and had moved the nail out of the way about a foot.

Re: off resonance detectors—–
Posted by Dave J. on 11/13/2010, 2:45 am, in reply to “Re: off resonance detectors—–“
Back in the 70’s and early 80’s Gardiner Electronics of Arizona (no relation to our engineer John Gardiner) was the king of off-resonance detectors. Very good engineer, several patents. He even ventured into multiple frequency. But alas, synchronously demodulated VLF induction balance proved to be superior.

–Dave J.
“clay domes” etc.
Posted by Dave J. on 11/14/2010, 1:18 am, in reply to “I can tell you one thing for certain —“
Same thing happens without any metal being present, especially with the higher frequency machines like the GB2. Electrically conductive soil, you break it up, and it’s no longer conductive. “Clay domes” esp. of montmorillonite composition are particularly well known for this.

Can’t comment on the behavior of the old high frequency TR’s since their operating principles are different, they don’t ground blance, and I haven’t used them.

–Dave J.

Re: Dave, I’ll also say “Thank You” for your reply.
Posted by Dave J. on 11/13/2010, 4:09 pm, in reply to “Dave, I’ll also say “Thank You” for your reply.”
Rusted flat iron (for example, bottlecap) will usually be less detectable in all metals mode than the same piece of metal would have been before it had rusted.

However, if the rust is the highly magnetic maghemite (gamma ferric oxide) type, it will jerk the discrimination (mostly reactive) signal around out of sync with respect to the resistive (metallic) signal. Depending on the characteristics of the discriminator, this time distortion of the discrimination signal can make the object look more electrically conductive than it really is. This can be demonstrated on the lab bench, it’s not hypothetical.

Flat iron (esp. with crimped edges like a bottlecap) even without rust exhibits reactive and resistive signals that are out of synchronization with each other– on a ‘scope in XY mode, it’s all over the screen instead of being an approximate straight line like a coin is. Magnemite rust tends to make the problem even worse.

Even an ordinary nail signal wobbles like a drunk in oscilloscope XY mode. When you see it on a ‘scope, it looks like a motion discriminator using those signals couldn’t possibly work, yet the amazing thing is that they still do.

–Dave J.

what about an 1898 V nickel?
Posted by Dave J. on 11/13/2010, 1:05 am, in reply to “Re: “HALO EFFECT””
What about an 1898 V nickel? I’d say the question is about the nickel, not the dubious or entirely absent “halo phenomenon”.

–Dave J.

Re: what about an 1898 V nickel?
Posted by Dave J. on 11/13/2010, 1:14 am, in reply to “what about an 1898 V nickel? “
Seems like every time somebody digs blue or green corrosion, there’s a big (relative to the mass of corrosion) chunk of metal in the middle of it. Nobody seems to find the massive corrosion “halo” that remains after the metal is mostly or entirely gone. Unless there is still a bit of metal left, and it’s shallow enough that it would have been easily detected in an air test.

–Dave J.

Re: what about an 1898 V nickel?
Posted by Dave J. on 11/13/2010, 4:18 pm, in reply to “Re: what about an 1898 V nickel? “
Please see my “HALO EFFECT” post in this thread where I discuss this at length. The presence of dirt shifts target ID, and discontinuities caused by digging a hole also shift target ID. How all that affects target ID depends on the characteristics of the dirt in that exact spot and on how the user was swinging the searchcoil.

It is the common experience of beeperists who make “test gardens” that a coin will usually be more detectable after it’s been in the ground several years, than when it’s buried. Sometimes beeperists attribute this to “development of a halo” but actually the explanation is that over time the disturbance in the magnetic soil profile caused by digging the hole gradually diminishes.

–Dave J.

copper sulfide?
Posted by Dave J. on 11/14/2010, 10:58 am, in reply to “Clarification”
The chemical conditions necessary for copper to corrode to sulfide don’t exist in anything that a person would call “soil”. Normal corrosion products would be oxide, carbonate, sulfate, organic acid salts; and hydroxide, hydrate, and organic complexes.

The oxide is a dull red; the other compounds are greenish or bluish.

–Dave J.

Re: wet ground vs. dry ground —
Posted by Dave J. on 11/12/2010, 11:41 am, in reply to “wet ground vs. dry ground —“
In general, within 50 to 100% of full scale balance range, a lower ground balance point increases sensitivity to high conductors. However you may not get an increase in sensitivity at settings below 50%.

The detector obviously has to be using the ground balanced signal in order to benefit from this.

–Dave J.

the thing in the foto
Posted by Dave J. on 11/9/2010, 9:31 am, in reply to “Re: I would encourage people to “never” buy this kind of crap……”
“copying” normally involves no violation of IP rights. usually it’s just the sincerest form of flattery.

in the photo the “display” appears to consist of a ring of LED’s in the searchcoil. about 7 years ago I had in my possession a “toy” metal detector with LED’s in the searchcoil as a gimmick, so the idea isn’t new.

the thing in the photo is probably junk, but at this point we don’t know that. The Chinese are gradually getting better at this stuff.

–Dave J.

Re: I need a refresher course
Posted by Dave J. on 11/8/2010, 2:21 am, in reply to “I need a refresher course”
A “true” all-metal mode is a non-motion or autotune/SAT/first derivative (“zip” sound on metal) mode which can be phase adjusted to cancel the response from ground matrix, without provision for causing any type of non-matrix signal to go silent.

In short, you hear everything, including ground matrix if you’re not ground balanced. Hearing everything is what makes “all metals mode” so powerful, and is also its greatest weakness.

There are other kinds of “all metals” modes (most commonly a discrimination mode with very little discrimination, just enough to quiet the ground down) but I think that most folks would agree with the description of “true all metals” I provided above.

–Dave J.

Re: ferrite filter —
Posted by Dave J. on 11/4/2010, 3:53 pm, in reply to “Re: ferrite filter —“
The clamp on ferrites (yes available at Radio Shack) serve an independent function, that’s why you see them as standard equipment on some computer related stuff. In the case of metal detectors they are ineffective against most types of interference but there are reports of them helping under some circumstances.

–Dave J.

Re: ferrite filter —
Posted by Dave J. on 11/5/2010, 8:45 am, in reply to “Re: ferrite filter —“
Clamp on ferrites will not help electrical interference from sources below VHF frequencies. Therefore no impact on interference from power lines, electric fences, automobile ignition, other metal detectors, or even AM broadcast.

Clamp on ferrites will sometimes help with electrical interference from cellphones, cellphone towers, short-range wireless communication such as Wi-Fi or wireless phones, UHF television, radar, and who knows what else is out there these days that didn’t exist 10 years ago.

If you try clamp on ferrites in one set of conditions and they didn’t help, it doesn’t mean they wouldn’t help someplace else, or for that matter in the same location at another time.

–Dave J.

Re: G2 Review and Video
Posted by Dave J. on 11/4/2010, 11:19 am, in reply to “Re: G2 Review and Video”
I can answer all that.

GB and disc settings are not retained on powerdown. But setting them again on power up is just a few seconds.

The coil is waterproof. There are no specific weather resistance features on the electronics enclosure, but rain hoods are available and don’t cost much. I admit rain hoods are a bit of a nuisance, but there’s so little during-the-hunt fiddling with a G2 that it’s no big deal.

The Teknetics grip (introduced on the T2 several years ago) is the most ergonomic grip in the industry. It may look wrong, but it is right for the vast majority of hands, that’s why we designed it that way. In the beginning it was short on mechanical robustness, but many detail improvements have been made, and nowadays it’s virtually unbreakable as well as a lot stiffer than it used to be. It is still just slightly flexible but that is part of what makes it almost unbreakable.

The stock coil is fairly light for its size, and the ergonomics are very good. Without going into the details of what makes for good ergonomics (we’re the industry leaders on that and don’t divulge all our trade secrets), slightly nose-heavy does not by itself make for the best ergonomics, but when the other things are right, slightly nose-heavy is part of what makes them right. ….The G2 ergonomics are the same as the Omega which has received high praise for excellent ergonomics. The ergos are not quite as close to perfection as the T2, but the lighter weight makes up for that, so most folks would rate an Omega or G2 as comfortable to swing as a T2. …..There are a lot of machines out there that have good “balance” just standing there, but once you start swinging them, the ergonomics go to heck.

Pinpoint is VCO’d. It may not sound pretty but it conveys more information that not having a VCO. All metals autotune and disc mode are also VCO’d. The disc mode is getting a lot of praise for the way it “talks to you” conveying information on what’s under the searchcoil. Again it’s not about making the machine sound pleasant, it’s about communicating information.

A spoon marked “USN” as we saw in the video would be U.S. Navy.

* * * * * * *

The G2 is probably going to generate a lot of questions of “why didn’t we do this or that, are we going to do this or that to it?” In general, we don’t talk much about why we do this or that, since we sell metal detectors, not “whys”. And in general we don’t talk about what we’re doing next in terms of engineering, for rather obvious business reasons and also because what we wind up doing is often different from what we thought we were going to do. All that having been said, I can hint at some of the “whys”……

The design philosophy behind the GB/G2 platform was to get as much function and performance as possible out of the simplest user interface possible, in a compact mechanical package and without having to price the thing in the thousand-dollar range. And, we succeeded. We even bested the Omega which was based on a fairly similar design philosophy. It was a tough job, and getting there wasn’t pretty, as a few of you may have noticed.

When the G2 question is “why”, the answer is usually to be found in the preceding paragraph.

–Dave J.

Re: G2 Review and Video
Posted by Dave J. on 11/4/2010, 3:47 pm, in reply to “Re: G2 Review and Video”
Bob,I don’t disagree with you on the quality of the digital audio. However for most folks it’s just fine, and what we’ve done with it in the disc mode has earned it high praise from some folks. That part has less to do with the mechanics of how we create audio, than with what we do with the audio.

There ain’t no one right/best way to design a metal detector, because each person’s preferences are different. That’s why there’s so many different models out there from various manufacturers, and why (happily) engineers will always have work to do. And beeperists like yourself can always look forward to new toys to play with.

–Dave J.

“Greek coils”
Posted by Dave J. on 11/5/2010, 8:34 am, in reply to “Re: G2 Review and Video”
The GB & G2 transmitter circuit is designed specifically to be used with DD searchcoils — more specifically the ones from the Tek “Greek” series (Omega etc.), also known more humorously as “Frat Bros.”

Fratbros concentrics do not align properly in the GB/G2 circuit. Some individual concentric coils may align well enough to “work” on the GB/G2 although performance may be degraded in subtle ways and with a change in temperature or in greater mineralization the coil may exhibit gross deficiencies or may stop working entirely. This caveat also applies to F75 series coils which a couple of folks have said they tried on a GB/G2 and they seemed to work despite the rather large inductance error.

Teknetics T2 coils are wired differently and are absolutely and completely incompatible.

–Dave J.

Re: just an idea —-
Posted by Dave J. on 10/22/2010, 10:30 pm, in reply to “just an idea —-“
It’s technically possible, but the compromises involved in doing it make the idea not very attractive. It’s a little bit like “Why can’t a car be a good city commute car and a good Jeep at the same time, without changing tires?”

The ability to detect a specific kind of object has to do with lots of important stuff apart from just the operating frequency.

–Dave J.

Re: according to—-
Posted by Dave J. on 10/23/2010, 12:20 am, in reply to “according to—-“
I suspect that’s not quite what George said, or that it’s taken out of context. I would suppose (perhaps erroneously) that every practicing successful metal detector engineer understands this stuff: George for sure does. It’s because they do understand the details that they DON’T drop the frequency to peak the resistive signal on high conductivity coins even though oversimplified physics would seem to dictate doing that.

The closely related DetectorPro and Fisher 1280X machines that run at 2.4 kHz, do so in order to minimize salt pickup. Their deficiencies are such that nobody will ever be tempted to mainstream them as land units. The DetectorPro is actually light enough to be used as a land unit if a person is convinced that “lower is better”, but it doesn’t stand a chance against an MXT, Tek T2, F70/75, Lobo ST, Tek G2 or Gold Bug Pro (13-19 kHz range machines) as a land coinshooter. Frequency is just one thing among many, that determine what sort of a beeper a machine will be.

–Dave J.

Re: you are right —-
Posted by Dave J. on 10/23/2010, 2:29 pm, in reply to “you are right —-“
Clark, if you want to drag me into an argument about what you think Payne told you, I wasn’t there. Suffice it to remind you that Payne knew how to design good VLF metal detectors, and that he didn’t drop the operating frequency down into the basement. None of the other good engineers in the business do it either. Even though most of us have never met face to face or even through email, on this frequency thing it’s almost as though we’d had a secret conference and walked out in unanimous agreement.

–Dave J.

Re: Yep
Posted by Dave J. on 10/23/2010, 12:41 am, in reply to “Yep”
Mike, there are people who clean up with BH TK4’s. (Running at about 6.5 kHz, just for the record.) It’s because they have “learned the machine” and don’t ask it to do what it can’t do, concentrating instead on what it actually can do. It’s a great tot-lotter, in good hands it’ll whip most over-$1K machines in that app. I hope the BH team doesn’t field it at the GNRS.

Using a 1280X on land is in this same category of knowing what it can’t do and using it for what it can do. The low frequency is actually a disadvantage for land use but the thing does beep on metal and the rest is up to the user.

Clark has a lot of fun jerking our chain and watching us rise to the bait. And how’s that for mixing pitbull and troutfishing metaphors? It’s all in good fun.

–Dave J.

Re: What’s the TK4 got?
Posted by Dave J. on 10/23/2010, 7:27 am, in reply to “What’s the TK4 got?”
About 6 inches max on coins. So-called “two filter” discriminator, done well. Ugly “muffler-on-a-stick” mechanical configuration. Analog meter that you quickly figure out isn’t really useful for anything besides battery test.

It’s almost impossible to find an unhappy TK4 owner. And it doesn’t have any significant manufacturing problems. It’s the one legacy BH product we make that hasn’t been redesigned since I came to work here in 2003. Every now and then I suggest redesigning it and then the boss reminds me “everyone but you likes it the way it is, so we ain’t gonna fix it!”

–Dave J.

Re: Dave J. ?
Posted by Dave J. on 10/22/2010, 7:27 pm, in reply to “Dave J. ?”
My response to questions about what we will or might do or not do in the future is usually “no comment” or something close to it. For me to “spill the beans” wouldn’t do ya much good anyhow: what happens a year from now will prove to be mostly different from what I presently envision– unpredictable stuff happens. Heck, trying to “predict” what happened two weeks ago is a gamble.

I can however assure you that the likelihood of the Impulse being brought out of retirement is miniscule.

–Dave J.

Re: Dave J. ?
Posted by Dave J. on 10/22/2010, 10:20 pm, in reply to “Re: Dave J. ?”
But Mark, then it wouldn’t be an Impulse.

I field tested the Impulse in the very-wet to ankle-deep stuff against another company’s unit with autotune, and it was no contest. Fully static won, the autotune simple threw the signal all over the place trying to keep up with the salt water whereas the static operation of the Impulse at least you could correlate what you were seeing with what you were hearing and mentally correct for it to some extent. And no, there wasn’t a problem with shielding on the other detector.

What ultimately killed the Impulse was that people stopped buying it. Without a good explanation why people would buy it now when they wouldn’t buy it a decade ago, it’s gonna stay dead.

* * * * *

And since I use this forum now and then for historical arcana and anecdotes, hoping that someones out there are doing a bit of compiling of the story of the industry, here’s a couple of related items.

1. That first PI machine that White’s had, red color in the cylindrical housing, static (non-motion)response, (mid 1980’s) I thought it was a pretty good unit, White’s got some difficult things right. Not real hot, but back then PI’s weren’t real hot. I didn’t like its successor, which was a little hotter but in my opinion a lot less well engineered.

2. I didn’t like the JW Fishers units of that era, they had the gain jacked ‘way too high and the low pass filtering too sluggish in order to make up for lousy basic sensitivity, so they were impossibly noisy and drifty and the response was “seasick”. The “undersea salvage” background of these units didn’t make them good beach units. I thought the mechanicals were shabby too. JW Fishers is off our radar screen: maybe someone who is familiar with what JW Fishers is doing nowadays will post to inform us.

3. The PI “mystique”– it’s the best and the worst of dealing with PI from a manufacturer’s point of view. Everyone wants it to be something it’s not. That makes a good salespitch easy, and it makes it hard to deliver on the customer’s expectation.

4. When we first started selling the Impulse, a guy in Australia wanted us to sell him one for half price to see how it would do for gold prospecting. He was sure that PI’s were the hot setup for gold prospecting. And he’d deliver us a field report. We told him VERY clearly that it was not designed for that purpose, we had very low expectations that he would find it useful for that purpose, but as long as he understood that and was willing to give us a field report, we’d sell it to him for half price. ….Well if you know human nature, you probably already guessed the rest of that story. He bought it, and it worked about like we told him we expected it wouldn’t. He demanded his money back and threatened that if we didn’t refund his money he would badmouth us everywhere he could, how we’d told him it would be a good gold prospecting machine and we ripped him off. (And as I recall, that threat was the content of his field report.)

* * * * * *

I’ll betcha that Carl Moreland has been with White’s long enough now to tell a few “customer horror stories”. Carl, your turn!

And, if you feel free to blab it (and indeed if you know enough to have an opinion), what’s your opinion of that old red White’s PI machine that I thought was a pretty good unit? (I’m not trying to set you up for anything, White’s subsequent PI units were a market success where the Impulse died, res ipso loquitur.)

–Dave J.

U/W machines
Posted by Dave J. on 10/23/2010, 5:24 pm, in reply to “Re: Dave J. ?”
I agree, Carl.

The CZ20 was part of what killed the Old Fisher. Manufacturing cost was higher than what they were selling them for, so they lost money right out of the gate. But they wanted the business so they kept right at it. Meanwhile, they’d forgotten how to seal them and how to tweak ’em up (CZ’s have a whole slew of tweaker pots). So thanks to the Roger Cimino Lifetime warranty, the machines just kept cycling through repair dept. at Fisher expense until the customer gave up. The only thing that stopped the Old Fisher from continuing to sell the thing was that the manufacturer of the pinpoint switch stopped making it and there was no direct replacement.

When people talk about how great the Old Fisher was “until BH bought it and ruined it”, I just shake my head. They don’t know carp. When I left Fisher in ’95 most things were still in halfway decent shape, but when I walked back in 12 years later I was shocked at what I saw. Same building, some of the same familiar faces, but a whole different company, the thing had become a living corpse. I didn’t have to see the numbers (although I did, and they were really, really bad), just walking in and glancing around told the story, that’s how total the big picture was.

Dragging the living corpse back out of the grave and standing it up wasn’t a pretty process, but by golly we did it.

We resurrected the CZ-20 as the ’21 (retooled for a different switch) and after an enormous amount of work, we’re finally actually making them for less than we sell them for, and when shipped they rarely come back. Victory, but at enormous cost.

I wish customers would stop asking for U/W machines so the temptation to manufacture them would go away!

–Dave J.

Re: U/W machines
Posted by Dave J. on 10/23/2010, 7:38 pm, in reply to “Re: U/W machines”
The thought’s been thunked about for a long time, but a sense of urgency has been missing. Even if the AT turns out not to be quite so waterproof as was intended, the idea is now on the map and isn’t gonna go away. It’ll be interesting to see how this plays out in the market.

–Dave J.

PS: “No comment.”

Re: Forum restructuring
Posted by Dave J. on 10/22/2010, 9:13 pm, in reply to “Forum restructuring”
Carl, I think you just got the most unanimous vote of agreement on something in the entire history of beeperdom.

That’s only half the miracle. The other half is that it was thumbs up!

–Dave J.

PS: I have a suggestion, and that is to put a salespitch banner at the top of the forum site saying something to the effect “If you like this forum, click on our sponsors’ ads every now and then and see if there’s something there you’d like to buy and thus support this forum.”

Having been reminded how much I like your forum and how unique it is, I will now check out that battery company sponsor, seeing that at the moment I’m dealing with engineering issues involving batteries.

Re: Forum restructuring
Posted by Dave J. on 10/22/2010, 12:16 am, in reply to “Forum restructuring”
Carl, I rather like your forum the way it is, not compartmentalized by subject. It wouldn’t work for a site with huge numbers of posts every day like Findmall or T-Net, but it seems to work well here.

It would help if new posts in a thread would bump the thread to the top (it’s a nuisance constantly having to read down the threads looking to see if they’ve been updated), but I don’t know if your forum software readily accommodates that feature.

Thank you for running this forum as the labor of love that it is, and being willing to keep it “different” and unique. There’s no other forum like it.

–Dave J.

seeing through dirt
Posted by Dave J. on 10/22/2010, 12:04 am, in reply to “Well, you could try a Whites …”
We manufacture a leading-edge night vision product called iGen. (Our Night Owl products are better known, but are conventional technology.) Well heck, if the iGen can see at night, with a little more tweaking we should be able to get it to see through dirt at least a foot or so (30 cm) in the daytime. Next step is to incorporate that technology into a metal detector, and dang, that’s gonna be a real game-changer!

Expect release April 1st. I’d predict which year but that’s more difficult.

–Dave J.

Re: Then Garrett will …
Posted by Dave J. on 10/22/2010, 10:14 am, in reply to “Then Garrett will …”
No prob, Bob. Imitation is the sincerest form of flattery, and better the sincere than the insincere.

–Dave J.

Re: Poor visual ID on Whites V3?
Posted by Dave J. on 10/21/2010, 2:54 am, in reply to “Poor visual ID on Whites V3?”
George, I was hoping someone would PM you and bring you up to speed. Since that evidently hasn’t happened, I hereby stick my neck out where angels fear to tread.

To put it another way, just because this is the forum where the experts hang out, doesn’t necessarily mean they’ll always be generous with what they know. In some cases they have trade secrets to protect, and in other cases they’re just trying to avoid unnecessary and fruitless conflict.

* * * * *

George, your Prizm with the new searchcoil is probably working just fine.

The V3 video you saw probably reflects a V3 working just fine.

Metal detectors have their limitations esp. in mineralized ground. Including the machines I’ve designed. Even including the White’s models I’ve designed.

* * * * *


Since I’ve now ventured where angels fear to tread, if someone wants to drag me into a debate on this forum over “which manufacturer’s machines are better” or worse yet the stupid “who’s the best engineer”, I’m not interested in going there. And as a few longtime forum denizens have noticed, those who try to drag me there and manage to succeed, usually find that it doesn’t come out the way they intended.

–Dave J.

Silver, dollars, gold, and the crystal ball
Posted by Dave J. on 10/14/2010, 10:49 am, in reply to “silver prices on the rise where will it top out ??”
That’s somewhat the same thing as asking where we think the US dollar will bottom out. (Same principle as with gold denominated in US dollars.)

Another part of that question is who will declare war against the dollar first– China or the USA. For different reasons neither wants the dollar to outright collapse, but if it does collapse, he who hesitates loses, so the advantage goes to whoever nukes the dollar first.

Since the economic and political and even military consequences of a sudden collapse of the dollar are so difficult to predict,it’s possible that the USA and China have a mutual behind-the-scenes agreement to sink the Almighty Dollar slowly, rather than to continue the nail-biting “whoever shoots first wins, but has to live with the corpse” game.

I’ve been watching gold, not silver. Gold has had this long, smooth runup for many months, and when it bumped its head against 1300 several weeks ago and seem to stagger a bit, I told the boss what went up must come down, this is the day to sell. Fortunately he did not take my advice, because that’s when the runup past 1370 began.

A couple years ago when gold bottomed out below 700, the very day it bottomed out I told the boss “this is it, buy today, you’ll never see it this low again” and by golly I called that one right. He was impressed and it went to my head. The last few weeks let the air out of that one. My crystal ball broke.

Trying to predict precious metals prices is fun because the whole thing is not random like shooting dice, it does have patterns and does respond to external events. So it seems like you should be able to figure it out. What makes it so tough is that precious metals futures is a poker game betting that you’re smarter than all the other players who also think they can figure it out, and outsmart each other and you too. The result is that patterns seemingly emerge, and then then vanish into thin air. The “rules” keep changing.

My favorite changed long-time rule is “people buy gold when they’re nervous”. The recent oil wars made a lot of people nervous, drove oil through the roof, but had virtually no impact on gold. Stocks run up when people are optimistic, and what has gold been doing a whole lot of for the last several years? Following the stock market! And that’s another rule broken: “when investors sell stock, they have to do something with the money, so they buy bonds or gold”. Where’s the money to buy gold coming from? Seemingly not from folks who bailed out of the stock market.

–Dave J.

Re: Mark 1 Lost Treasure magazine article info
Posted by Dave J. on 10/5/2010, 2:25 pm, in reply to “Re: Mark 1 Lost Treasure magazine article info”
I see some confusion going on.

Lots of things have been invented which the public did not see at the time, and lots of things have been invented/designed independently of something else that was already in public view but not “copied”.

There are a few people who have the idea that Payne invented the modern metal detector and that everyone else copied him. That’s nonsense, and I rather doubt that George himself would say a thing like that.

There are some folks who seem to want to have a beauty contest “who’s the best beep engineer, George or Dave or maybe even Bruce?” More nonsense. Each one of us has done bunches of stuff the other didn’t do or at least it never came to market. And nearly all of this stuff we did on our own without having to copy from the other guy. In most cases there wasn’t even anything to copy.

And it ain’t just Bruce, George, and Dave either. There’s Jack. And John Earle. Mark Rowan. Several engineers working for Charlie including Charlie himself. Other engineers in the USA and in Europe also, whose names aren’t well known but made their contribution to the industry.

-Dave J.

Re: Mark 1 Lost Treasure magazine article info
Posted by Dave J. on 10/5/2010, 10:27 pm, in reply to “Re: Mark 1 Lost Treasure magazine article info”
Sorry, Bob, I don’t have a list of engineers’ patents. In theory it should be easy to find them in a USPTO patent search, but the search engine is dumb as a rock. If you don’t already know exactly what you’re looking for, and I do mean exactly, it misses stuff. I’ve often been unable to find one or more of my own patents online.

I look forward to the article on George Payne. He is one of the greats of the industry, and since he’s no longer active, this is a good time for his story to be told.

Actually I know a whole lot less about George and his product history than you seem to think. George and I never worked together nor do I recall that we ever had any direct contact. During his 1980’s glory days Fisher pretty much ignored his products since our product development efforts were in a very different direction. I didn’t learn how Payne calculated phase for target ID (a particularly difficult thing to do well in analog circuitry) until in 2003 I went to work for FTP, which had inherited his designs. Of all the ways I’ve seen it done, his was definitely the cleverest, not out of the cookbook at all. The “Payne circuit” is still the backbone of the BH product line.

–Dave J.

PS: that post by someone suggesting that I didn’t invent “notch”, well, heck, I suppose that darn near every engineer in the business has invented “notch”. It was probably being done in the 60’s or earlier on industrial materials testing apparatus before anyone was doing it on a consumer swinger-beeper. The VLF induction balance discriminator was invented in the late 1800’s even before the vacuum tube: I don’t recall whether or not the patent disclosed a notch system, but even if it didn’t, the inventor may well have invented it but failed to disclose it in the patent.

Re: CZ 20 quicksilver goes dead when submerged in Salt Water
Posted by Dave J. on 10/3/2010, 12:08 pm, in reply to “CZ 20 quicksilver goes dead when submerged in Salt Water”
I bet it goes dead the instant the seawater makes contact with the metal components on the front panel.

Furthermore I’ll speculate that the metal components are grounded to the negative rail and that the shield of the searchcoil is grounded to analog ground (or possibly vice versa, I don’t remember for sure). If there is a place on the searchcoil where the shield is exposed and makes contact with the saltwater, no problem as long as it doesn’t get connected to the negative rail via the front panel components. When that happens, analog ground (which cannot supply much DC current) gets sucked down and kills the biasing needed for the machine to work.

Your searchcoil is probably white, and the shielding paint is black. If you can see any exposure of black, or can see a little crack that could lead down to the shield paint, wash it thoroughly with distilled water, and after it is thoroughly dry, try “painting” it with something sturdy that will adhere well. 5-minute epoxy would be a good candidate.

Please let us know if that works for you.

–Dave J.

Re: CZ 20 quicksilver goes dead when submerged in Salt Water
Posted by Dave J. on 10/4/2010, 10:25 am, in reply to “Re: CZ 20 quicksilver goes dead when submerged in Salt Water”
I vaguely recall a report like yours when I was back in Los Banos (and it was probably a 1280-X, not CZ20) where we tried to replicate it in fresh water and failed, it wasn’t conductive enough.

Sorry, I’m out ideas other than to sent it in for repair. Because the CZ20’s were such notorious leakers, we put a lot of work into fixing the sealing problems on the CZ21, it’s my understanding that we convert the unit to 21 spex which costs a bit but we don’t want to do a repair and then send back a leaker. You can call Daniel at the factory 915 633-8354 and he can explain how this works, and maybe he’s seen the same problem before, he’s been involved with CZ’s since they were first introduced in 1991. If you decide to send the machine in, Felix will probably be the one to handle the actual transaction.

Sorry we couldn’t figure out a cheap and easy fix, but hey, we gave it a shot.

–Dave J.

Re: metal detector settings
Posted by Dave J. on 10/1/2010, 2:38 am, in reply to “metal detector settings”
CZ’s: Search either in all metals autotune, or in disc mode with iron not knocked out and digging everything. These machines are inherently salt balanced and as such they have low sensitivity to small gold and will miss entirely some gold chains that a single-frequency machine will give a solid report on.

The 1280-X Aquanaut is a completely different metal detector in a somewhat similar housing. It runs at 2.4 kHz. That makes it not very sensitive to the smallest detectable gold, but probably better than the CZ’s.

In the really wet salt, esp. in the surf, the CZ’s are much superior to the 1280-X.

For beeping on a white sand beach (i.e. not much black sand) the Tek Omega has a very good reputation, and early reports on the new Gold Bug platform machines suggest that they are at least as good. This is in part due to their ability to ground balance all the way to wet salt, but there are other “secret sauce” factors at work which are also partly responsible. The Gold Bug type machines on a nonmineralized beach will lose a lot of sensitivity to the small gold when balanced to wet salt, but under those conditions they’ll still be superior to the CZ’s on the small stuff. On the drier beach, the Omega is quite good on small stuff and the GB platform machines are smokin’ hot (being leading-edge gold machines).

Of course the Omega and the GB platform products will not survive a drop in the splash, so if you’re literally searching in the surf you need to be careful lest you destroy the machine.

I have personally spent very little time on saltwater beaches with metal detectors: what I’ve said is based mostly on operating principles and on field reports by other people. It’s possible that someone with a lot of experience will disagree with something I’ve said.

–Dave J. (the guy who designed all of the machines mentioned above)

Re: Lost Treasure magazine
Posted by Dave J. on 9/28/2010, 2:15 am, in reply to “Re: Lost Treasure magazine”
The treasure mags ain’t dead yet, but times are tough for them just as for other print media in general. Television taught people not to read, and then the Internet siphoned off the remaining non-illiterates.

I’m an olde phart, grew up reading print media and not liking television. I now embrace the Internet but with something less than love: I define a “browser” as “a file access tool that doesn’t know how to browse”. My daughter just received a “Nook”, a wireless linked pocket electronic “book”, for her birthday, courtesy of the old man. Pages too small and too awkward to flip, and it’s basically a device for selling you books at half price that you could have gotten in a used bookstore (even an Internet bookstore, our family pioneered that, shameless plug for Zephyr books in Reno NV) for even less, including shipping, and with a real bookstore ya gots a real book and it even has resale value if you don’t want to keep it forever.

The treasure mags have it tough. Not only is the Internet eroding the value of paper as perceived by most folks, the reader base in the USA is the Harley Davidson Generation– mean customer age increasing by ten years every decade. Perilously little new blood, and beeping can’t keep the older folks alive forever.

Call me Neandertal or Luddite if you like, but I want the mags to stay in business. With the right formula, a magazine can survive in a world dominated by electronic media. The strength of a successful magazine these days is focus and challenging content.

The USA treasure magazines have for too long (in my opinion) lacked visionary leadership. The inside dope is that there is really exciting stuff happening all over the world, and readers would love to hear about it, but the mag management hasn’t yet figured out how to connect the dots. For the passionate beeperist, the forums have replaced the magazines.

In all fairness to the magazines, they ain’t got much money to work with. Beeper mags are not high circulation, which makes per page production costs higher than a high-circulation mag, and there’s almost nothing left for the cost of good editorial content.

A new business model is needed, one in which the Internet is regarded as a key resource rather than a competitor, one which starts every morning with the proposition that the sun will circle the planet in 24 hours and go thou and do likewise. Yes, American readers want to hear stories of stuff happening elsewhere that boggles their imagination, and readers overseas want to read a USA beep mag that acknowledges the rest of the world, not just civil war paraphernalia and US coins.

Another part of a new business model is reassessing how relationships with advertisers drive the business. Back in the bad old days it was adjusting editorial content to please advertisers– I don’t mean editorial content was determined entirely by advertising revenue, it just happens to be a fact of life that a publisher has to adjust to in order to stay in business.

In a new vision of what paper print is for, paper can be viewed as the radical edge, like quite of the few of the mags you find at Barnes & Noble bricks & mortar bookstores. The mainstream lost its need for information on the way to the television channel selector, so those who still want to learn stuff aren’t the mainstream.

Just kyckin’ some ideas around in a public venue, hoping for the best of all possible outcomes and willing to settle for less.

–Dave J.

Re: Is my Prizm 6T defective?
Posted by Dave J. on 9/26/2010, 9:59 pm, in reply to “Is my Prizm 6T defective?”
I’m not familiar with the Prizm specifically, but the symptoms you describe sound most likely a badly out-of-balance searchcoil. If you have access to another searchcoil which is specified for the Prizm (say another machine in your arsenal, the machine of a friend, or something on hand at your local dealer), try that and see if that solves the problem.

But before you do that, make sure fresh name-brand alkalines are in the battery compartment. Sometimes batteries a person thinks should be good, aren’t.

–Dave J.

e: iron detector
Posted by Dave J. on 9/25/2010, 8:40 pm, in reply to “iron detector”
Basavaraj, you’ll have to provide a better description of the project.

If it involves following the path of an iron or steel pipe, you probably need a “line tracer”, also known as a “pipe and cable tracer”. If it is some other application you’ll probably need a high-sensitivity magnetometer such as is used for geophysical surveying.

It’s possible that what you are hoping to be able to do, can’t be done with anything presently available.

–Dave J.

Re: Tesoro…… seems to be going……..
Posted by Dave J. on 9/24/2010, 1:19 am, in reply to “Tesoro…… seems to be going……..”
Tesoro may be a competitor of FTP-Fisher, but that doesn’t make them an enemy. Tesoro has played a very positive role in this industry over the years. In 1995 Jack rescued me from a certain who-shall-not-be-named engineering manager at the “old Fisher”, and put food on my family’s table in Prescott for two years. The whole experience left me with many good memories.

So like John N, I am also sorry to see Tesoro apparently sliding into oblivion.

— Dave J.

PS: The question of why I left Tesoro will probably never be answered in public. Suffice it to say that it was not (as some might suspect) to go to work for a certain other “W” company (that happened later quite as a surprise), nor was it about personal conflict with Jack or about legal or ethical issues. No soap opera. My departure from Tesoro revolved around ordinary business matters, and neither Jack nor I burned the bridge in the process.

In a previous post here I expressed my hope that someone in beeperlandia is compiling a history of this industry. I offer this post as one piece of information for the pile.

Re: meteorites
Posted by Dave J. on 9/15/2010, 5:41 am, in reply to “meteorites”
cheap one will work if you get lucky.

the most important feature for space rock beeping for less than US$1,000 is an “autotune” type ground balanced mode where you hear everything whether you wanted to or not.

The principles of meteorite prospecting are not the same as gold prospecting, but they have a lot in common. That is why the most popular machines for meteorite hunting are machines designed in part or in their entirety for gold prospecting.

Some of these details have already been discussed in the other recent meteorite thread.

Dave J.
chief designer, FTP-Fisher

Re: C.Scope detectors
Posted by Dave J. on 9/8/2010, 2:38 am, in reply to “Re: C.Scope detectors”
Back in the 80’s-90’s, we Fisher folks used to get a kick out of C-scope’s obsession with copying Fisher. Not just trademarks (Fisher was originally known as “M-scope”) but features and form factors. Imitation is the sincerest form of flattery, and there was no questioning their sincerity. We didn’t get mad: after all, what kind of a market threat did C-scope represent to us? None. They were copying.

At one point I got my hands on one of their quasi-knockoffs, as I recall their version of the 1265-X, called something close to that. Actually it was a pretty good metal detector, and it was not a carbon copy, it was conceptually similar but all the details were different. The irony was that they had good engineering, and yet couldn’t create their own product concepts.

I don’t know any of the personalities involved, but must guess that it was a combination of good engineer with crappy marketing, and the marketing dept. won. Had C-scope stopped playing second fiddle to Fisher and played their own tune, the history of British metal detector manufacturing might have come out a lot different.

–Dave J.

Re: Pot calling Kettle black
Posted by Dave J. on 9/8/2010, 12:21 pm, in reply to “Pot calling Kettle black”
Dory, I’m happy to give Payne credit where credit is due, but the idea that he invented the modern metal detector and everyone else copied him is nonsense. To my knowledge not even he has ever suggested such a thing.

I don’t know how much of the old White’s lineup was part of the Payne legacy, but I never copied anything at all from Payne (apart from modernizing his Bounty Hunter designs in the last several years). I’m close to certain that Jack never copied anything from Payne. Not aware of anything that Charlie copied from Payne. I don’t see Payne-copying in any of Minelab’s stuff. Most of White’s stuff these days are designs which owe nothing to the Payne legacy.

Payne’s famous target ID system sampled the signal on the peak of the second derivative using the zero crossing of the first derivative to time it: Fisher already patented that but figured it wasn’t worth the trouble to sue. My guess is that Payne was unaware of our patent and came up with the idea independently.

Payne’s legacy was the Bounty Hunter line and some of the White’s stuff. And Discovery Electronics, whatever that is. Had none of that ever happened the rest of the industry would likely have done more or less what it did anyhow. And down in El Paso, the new Teknetics line uses only one thing from Payne– the Tek trademark.

–Dave J.

Re: Let’s see now
Posted by Dave J. on 9/8/2010, 4:29 pm, in reply to “Let’s see now”
Dory, you may imagine that all that stuff was copied from Payne, but that has nothing to do with the facts. All those things were developed independently from Payne and in many cases before what Payne was doing became public and therefore couldn’t have been copied from Payne. There’s no point in your arguing with me about it because I know firshand, I was the guy.

Payne was a creative and innovative engineer. A number of the products we manufacture now are updated versions of products that originated with Payne. If there’s something that was really worth copying in the old Tek platforms, it was the clever circuit that computed the ratio of two signals for target ID. Yet to my knowledge nobody in the entire industry ever copied it. Other engineers did things their own way.

If it makes you feel any better, I did copy Jack’s noninverting differentiator circuit. It didn’t change the operation of any products from a user’s perspective, but did cut manufacturing cost just a hair.

–Dave J.

Re: Coil expertise needed……..
Posted by Dave J. on 9/7/2010, 12:33 am, in reply to “Coil expertise needed……..”
the Fisher Impulse (no longer in production) searchcoil was based on the same principle although the dimensions were different.

It’s not magic, it’s a compromise. a large coil is good on large deep targets and a small coil is good on small shallow targets. Having two sized windings makes it possible to do a halfway decent job on both classes of targets.

Induction balance searchcoils with which you seem to be more familiar work on different principles.

–Dave J.

Re: looks like —-
Posted by Dave J. on 8/23/2010, 9:14 pm, in reply to “looks like —-“
Clark, it’s not a secret, the problem is that there is no straight answer to your question. Not only do metal detectors differ in many ways other than operating frequency, there are many different kinds of electrical interference, many of which don’t have anything to do with what frequency the metal detector runs at.

Every engineer has their own favorite techniques for dealing with electrical interference, but each technique is effective only for certain kinds of electrical interference. That’s why in one environment Machine A may be very noisy and Machine B can be cranked all the way up, yet in a different environment Machine A may be happy and Machine B may go berserk.

The most universally effective technique for dealing with electrical interference is to crank the sensitivity down. Everybody wants to believe that sensitivity controls are for cranking sensitivity up, when in fact the only reason that manufacturers put them on machines is to crank the sensitivity down.

–Dave J.

Re: I believe what —-
Posted by Dave J. on 8/24/2010, 3:29 pm, in reply to “I believe what —-“
Clark, your question was whether the operating frequency had a lot to do with susceptibility to electrical interference. It has something to do with it, but not a whole lot. The single most important factor is whether the machine is hot, or not. I’ve never seen electrical interference bother a BH Junior, but it’s got a sensitivity control just in case.

Metal detectors are not cellphones or computers. And, not all powerline interference is of the same type. There are always things that can be done to improve their ability to ignore electrical interference but if we (or anyone else) made one which was to all intents and purposes invulnerable to electrical interference, no serious beeperist would buy it. This is why on your favorite machine (no matter what make & model it is or what frequency it runs at), the manufacturer provided a sensitivity control the purpose of which is to make the machine usable in the presence of electrical interference.

–Dave J.


Re: turning the sensitivity down —
Posted by Dave J. on 8/24/2010, 9:50 pm, in reply to “turning the sensitivity down —“
Ya got a point there, Clark. Crank that sensitivity all the way to the max and go chase dem rabbits!

If you complain about electrical interference but won’t use the features in the machine the manufacturer put there to deal with it, don’t expect folks here to take you very seriously.

–Dave J.

Re: Which coil best?
Posted by Dave J. on 8/21/2010, 11:26 pm, in reply to “Re: Which coil best?”
Folks out West (USA) don’t appreciate how homes are heated affects the soil in the vicinity.

Wood fuel contains very little iron, and the ash usually contains only small fragments of charcoal which although electrically conductive, are small and so don’t usually cause too much grief with metal detectors. In the short run the wood ashes when tossed out are electrically conductive but over time, rainfall leaches the conductive ash minerals away. In drier climates the leaching process may take decades or longer, but in such cases the soil is dry most of the time so the minerals (in their dry state) are not electrically conductive.

Back East, not only wood, but also coal and coke have been used for household fuel. Coal is dirty stuff but where it’s available, it’s cheap. It contains iron minerals which the burning process reduces to metallic iron or to magnetically active reduced iron oxides. And, as it burns it turns some of the unburnt coal into coke, which is a lot more electrically conductive than charcoal due to its higher density. When the ashes get thrown out you have a mixture of magnetic iron minerals, highly conductive coke residue, and ash minerals which are electrically conductive when wet. Over the course of decades, an area where stove and furnace ash was dumped can accumulate a lot of stuff that drives metal detectors nuts, yes even PI machines. In the humid East (USA) the conductive ash minerals eventually leach away but the iron and iron minerals remain in place, often converting to the even more notorious maghemite (red rust), while the coke is chemically inert and will remain in the soil. Freeze-thaw and other soil mechanical processes may eventually break the stuff up into smaller fragments, reducing its electrical conductivity, but that probably takes thousands of years or longer.

And then there’s coke. Coke is fire-roasted coal, just as charcoal is fire-roasted wood. The primary purpose of converting wood to charcoal is to drive off the hydrate to make the fuel lighter and more compact and thus more economical to ship. The primary purpose of converting coal to coke is to drive off sulfur and other impurities so that the stuff can be used to smelt iron and a few other metals, and (in the bad old days) to generate “producer gas” for industrial and municipal fuel use in the same ways that natural gas is used nowadays.

In other words, charcoal is produced for use in primitive economies and coke is an industrial product.

In regions where coke is produced, it usually is (or has been) made available as a fuel for household use. For household use it is preferred because it is denser and burns cleaner. Because coke is a high-grade fuel, higher grades of coal (if available) are used to produce it, and therefore coke is usually lower in iron and ash impurities, although the iron smelting industry does not regard the iron content as a nuisance, only the ash.

When household coke ash gets tossed into the back yard, the problems from a metal detecting standpoint are basically the same as those of coal ash (clinkers, cinders, etc.) With coke fuel residue, the biggest problem will usually be unburnt pieces of coke, which are so highly conductive that large pieces can register into the high coin range on a metal detector.

In the humid East, people often dumped their ashes in the vegetable garden or fruit orchard, since the soils are deficient in calcium and other minerals which are present in ash. Ash was used as fertilizer. Sometimes it was dumped into the privy. And sometimes it was just dumped into an ash-heap which may have also been the compost and manure heap. Finding lumps of electrically conductive unspent carbon fuel may not be your favorite beep, but knowing why the stuff was dumped in certain places and not in others can help you decipher the site use and lead to more productive beeping.

Some sites are literally blanketed with such miserable stuff. This is because coal and coke are used on an industrial scale and the spent fuel is discarded on an industrial scale. Iron and other mineral smelting operations also produce large amounts of silicate mineral slag which is usually high in magnetically active reduced iron minerals. The stuff gets piled up until someone figures out how to get rid of it. It is usable as landfill aggregate and being cheaper than natural aggregate (because someone wants to get rid of the stuff) it does get used as landfill aggregate. Say for instance there’s a hilly area where you want to put a baseball diamond. You need cheap fill material to create a large flat land surface. You use industrial waste aggregates as the primary fill material and mix some topsoil into the upper layer so the grass can grow. It’s not a wicked plot against beeperists, it’s just a good way to build a baseball diamond if industrial waste aggregates are available.

Every situation plays by its own rules: what I am reciting are broad generalities.

–Dave J.

rules of thumb
Posted by Dave J. on 8/21/2010, 3:31 pm, in reply to “Which coil best?”

Difficult conditions (lots of trash, high mineralization, high electrical interference, irregular ground surface): use smaller coil.

Easy conditions (not much trash, low mineralization, no electrical interference, smooth ground surface) : use larger coil.

Concentrics are generally better in light mineralization, where there are lots of steel bottlecaps, and in the presence of electrical interference.

DD searchcoils are generally better in high mineralization (less ground signal pickup) and in trashy areas (sharper target separation). Under these conditions the advantage of DD’s over concentrics is more pronounced in the larger sizes, there not being much advantage the small sizes.


Nowadays quite a few metal detectors have transmitter circuits which work only with DD’s.

It seems to me that overall most experienced users prefer DD’s.

A few years ago there was a trend to larger and larger searchcoils to “get more depth”. But the advantage was mostly illusory: actually, larger searchcoils usually don’t give you much additional depth, mainly just a broader sweep that loses targets in trashy areas due to masking. Nowadays many experienced detectorists use a small searchcoil as their primary coil because they pick more finds out of trashy areas that have supposedly been “hunted out” with larger searchcoils.

Another advantage with a smaller searchcoil is psychological– it forces you to pay attention to what you’re doing. With a large searchcoil it’s easy to get lazy and sloppy. Most sites are trashy sites, and “lazy and sloppy” means you leave the goodies in the ground for someone who works the area with skill and diligence.

Finally, nowadays you often have a choice between round or elliptical. Manufacturers like round searchcoils because they’re easier to manufacture. However for a given surface area and winding configuration (say comparing an 8 inch round concentric to a 10-11 inch elliptical concentric) the performance advantage is always to the elliptical because it has a broader sweep and better target separation.

The foregoing remarks pertain to searchcoils used on so-called “VLF” and “multifrequency” induction balance metal detectors. I’ll leave it to someone else to comment on searchcoil selection for pulse induction metal detectors.

–Dave Johnson

Posted by Dave J. on 7/22/2010, 2:58 pm, in reply to “Re: VLF All Metal Differences?”
a bit off topic in this thread, but since you asked, here’s the link:


–Dave J.

Re: Bad Ground
Posted by Dave J. on 7/17/2010, 12:08 am, in reply to “Bad Ground”
Reg is right about lofting the searchcoil in the bad dirt. The trick is in knowing how much to loft it, which is highly dependent on ground conditions as well as the expected target distribution; and also the circuit design and the kind of searchcoil the machine is outfitted with.

Regarding searchcoils specifically in bad ground:

1. A DD is not necessarily “deeper” than a concentric if you use it wrong.

2. A smaller searchcoil will often get better depth than a larger one.

Reg is also right that in bad ground, you’ll get best results with a sweep that’s slower than what will give you best results in easy ground.

–Dave J.

Re: what new detector technology would you like to see
Posted by Dave J. on 7/12/2010, 2:19 am, in reply to “what new detector technology would you like to see”
I would like to discourage several scenarios:

1. Including GPS.

2. “Tuning the machine to the gold frequency”.

3. Methods requiring the use of radioactivity.

Mainstream detection technologies still afford a lot of room for improvement.

–Dave J.


Re: what new detector technology would you like to see
Posted by Dave J. on 7/13/2010, 11:29 am, in reply to “Re: what new detector technology would you like to see”
Same game, but better. By way of analogy: a new car nowadays is pretty much the same thing as a Model T Ford, just with lots of improvements. A Boeing 747 is a game changer for those cross-country trips, but the thing in your driveway is still a car, not an airliner.

And not a horse, either. In the age of BFO’s, the VLF was a game changer. BFO’s are dead.

I don’t see anything on the horizon that threatens to do to the VLF (or PI) what the VLF did to the BFO. Underground radar will eventually become a consumer technology but won’t replace VLF and PI based machines.

Maybe something eventually will relegate VLF and PI to the garbage can but I don’t expect to see that happen in my lifetime. And it won’t be an improvement on “molecular frequency discriminators”.

OFF TOPIC: I have a molecular frequency discriminator. Actually, two of ’em. I have used them to find and to discriminate natural gold. The molecular frequency of gold is in the reciprocal 400-900 nanometer range, and that’s where my molecular frequency discriminators are tuned.

They’re called “left and right eyeballs”.

–Dave J.

Re: what new detector technology would you like to see
Posted by Dave J. on 7/14/2010, 2:48 am, in reply to “Re: what new detector technology would you like to see”
Today’s VLF machines are what they are, Carl, and I mostly agree with you on the target ID thing.

Your question “where do you see major improvements happening”? is an awkward one. Seeing and happening have had vast gulfs between them for thousands of years and beeperdom has not entirely escaped that fate.

–Dave J.

The saga of BP9
Posted by Dave J. on 7/10/2010, 1:06 am, in reply to “Re: PPD1 PI?”
The “old Los Banos Fisher”, in the late 80’s came close to marketing a visual target ID PI machine we called the “Bipulse Nine”. The problem was that Jim Lewellen was madly in love with it but those who tried it out told him that his baby was ugly. I just betcha that one or more people reading this were there during the baby shower (in Oklahoma)and got to kiss the baby. Anyone care to play “kiss and tell”? Jim isn’t around any more to have a cow over it, and anyway he finally agreed with the critics and answered them with the CZ series. So it’s no disrespect to spill the beans. One of those “it was all funny in retrospect” situations.

C’mon, guys and gals, any takers? Who was there? I wasn’t, I only had to deal with the aftermath.

–Dave J.

Re: The saga of BP9
Posted by Dave J. on 7/19/2010, 6:36 pm, in reply to “Re: The saga of BP9”
With the discrimination & target ID stuff removed, it became the Impulse.

–Dave J.


first TR
Posted by Dave J. on 7/19/2010, 1:01 pm, in reply to “Re: A H Electronics”
The first synchronously demodulated induction balance discriminator was a benchtop counterfeit coin detector patented in the late 1800’s before vacuum tubes. Synchronous demodulation was accomplished with a mechanical commutator. I have a copy of the patent deep in my “file pile” somewhere.

Synchronously demodulated VLF induction balances were in existence at least in the 1950’s but that was expensive cumbersome high-tech and vacuum tubes aren’t very good at that sort of thing anyhow. The BFO was easy to get to work right, and inexpensive, so that’s where consumer market beeping started out.

The bipolar semiconductor transistor was invented about 1928. It was based on copper oxide and the DC biasing in the app circuit schematics provides evidence that it worked. (Otherwise one would not have known back then how a bipolar transistor should be biased.) Unfortunately the manufacturing process was not reproducible and it was never commercialized. Another patent somewhere in my deep pile.

–Dave J.

dirtfisher history
Posted by Dave J. on 7/7/2010, 1:59 am, in reply to “army mine detectors”
Fisher is the world’s oldest manufacturer of metal detectors, having been in business since about 1935. I don’t think the company got into “hobby” beepers until the 1960’s or so. It was like Tom says, industrial underground detection. And up until the 1960’s, radionavigation and marine communications radio gear as well. I think Fisher made mine detectors during WWII but I have no hard evidence of that.

Dr. Gerhard Fisher may have been the originator of his particular style of 2-box unit, but other types of 2-box units were in existence during WWI and probably earlier. They did not rely on vacuum tubes, just darn good attention to detail. The oldest metal detectors date back to the 1800’s before there were vacuum tubes.

Alexander Graham Bell built an audio frequency induction balance for the purpose of locating the bullet in President Garfield so that surgeons could remove it (no medical X-ray yet) but the machine seemed not to work right. It was only afterwards that they realized that the metal hospital bed had probably defeated it. That was the cover story anyhow: I say more likely that the induction balance drifted out of calibration.

Even earlier than that, there was a patent issued on a synchronously demodulated audio frequency induction balance discriminator, same principle as used today in most machines. Its purpose was to detect counterfeit coins. It was a benchtop unit, not a “swinger”. Without electronics being in existence yet, the demodulator was a mechanical commutator.

That wasn’t the only technology before its time. The transistor was invented and patented in the late 1920’s (I have a copy of the patent somewhere buried deep in my piles of interesting stuff) but luck was stacked against it. It was copper oxide, and you could make good rectifiers with copper oxide. But making triodes (transistors) from the same material intially proved to be a chancy proposition and rather than persisting until it was gotten right, the developers of the copper oxide transistor gave up. To my knowledge nobody ever gave it a second chance. It was only after WWII that Bell Labs reinvented the transistor in germanium (probably unaware of the earlier copper oxide patent) giving birth to modern solid state electronics.

The portable electronic synchronously demodulated VLF induction balance was, as far as I have been able to determine, first a mine detector developed during late WWII using vacuum tubes. Its forte was its ability to balance out ground and searchcoil residual reactive imbalance, and it probably could have detected coins and the larger bullets. During the 1950’s the lowly non ground balanced BFO proved more suitable for civilian hobby use than synchronously demodulated induction balances, which did not come into their own until the early 1970’s. Motion discrimination was added to them in the mid to late 1970’s and that basic technology is still the mainstay of the metal detector industry today. With lots of improvements of course!

–Dave J.

Re: use the TR mode—
Posted by Dave J. on 7/6/2010, 3:23 pm, in reply to “use the TR mode—“
Thanks, Clark, for risking being declared a heretic. You’re forcing me to look at some things a little differently than what I’ve customarily done.

In another post in this thread you said something like “an experienced TR user will clean your clock on the deep coins”. That would not necessarily be true under all conditions (as you pointed out above) but there are certainly conditions where that would be true. And the secret (as you say) is to crank the sensitivity as far down as necessary to stabilize the machine.

Another secret (I just betcha) is to adjust discrimination so it nulls on most iron but lets some slide through with a weak response. Did I get that part right?

–Dave J.

Re: use the TR mode—
Posted by Dave J. on 7/6/2010, 7:30 pm, in reply to “Re: use the TR mode—“
Tom, I’m not exactly a newbie to this, been designing metal detectors for 29 years. That doesn’t mean I can’t learn anything any more. I understand what Clark is talking about and I agree with him– not necessary on every point of hyperbole, but on the principle there are conditions where a knowledgeable beeperist with a good TR used in discrimination mode (i.e. not ground balanced) will be able to find coins deeper than someone with a good VLF motion machine.

This discussion is about single frequency machines– TR vs. motion, and what operating frequency. There are no static TR multiple frequency machines and there are no “true discriminating” PI’s, and in both cases if you ask “what is the operating frequency?” there is no straight answer. Different animals that aren’t relevant to this particular discussion.

–Dave J.

Re: Frequency vs. depth
Posted by Dave J. on 7/4/2010, 10:53 pm, in reply to “Frequency vs. depth”
Carl, you’re right that the conventional wisdom is that lower frequencies are better for the high conductors. But it’s a generality.

I can think of ways to design two machines the same except for frequency, and the higher frequency machine will do better on the high conductors. Ways that are representative of some machines that are on the market.

Without spilling the beans, I can say that there are technical reasons why a higher frequency machine might do better on high conductors. So it’s probably not just your imagination.

That having been said, some of the lower frequency machines do very well on the high conductors in part because they are lower frequency machines. In other words I am not dismissing the prevailing “rule of thumb”.

–Dave J.

Re: metal detector circuit diagram
Posted by Dave J. on 7/1/2010, 12:27 pm, in reply to “metal detector circuit diagram”
Yasir, the only kind of metal detector that will find objects 2 meters deep is a pulse induction machine with a very large searchcoil (say 1 meter square). It won’t find coin sized objects at 2 meters depth (and may not find them even on the surface)but if everything is done right it will find larger objects.

There are several experimenter pulse induction circuits on Carl-NC’s Geotech website. Someone here can probably provide a link to a specific circuit that people have had good luck with.

I don’t know what you regard as “simple”: getting a pulse induction metal detector to work well requires a certain amount of electronics knowledge and skill. It’s not just “follow the instructions and expect it to work”. It is however a lot easier than trying to get a VLF induction balance to work well for such an application.

If you are looking only for iron and steel (magnetic metal) objects, a magnetometer will find it deeper than a metal detector. However I am not aware of any do-it-yourself magnetometer project plans, the result of which is supposed to be a magnetometer capable of finding buried metal. Commercial magnetometers of that type usually cost in the US$600-1200 range.

–Dave J.

Re: I Know Fisher Recently Had Some Cheap Chinese Knockoff, Whites Did In The past. Garrett Has One Too!
Posted by Dave J. on 6/6/2010, 11:00 pm, in reply to “I Know Fisher Recently Had Some Cheap Chinese Knockoff, Whites Did In The past. Garrett Has One Too!”
I have sitting in my office a Bounty Hunter-looking machine which has the same electrical features and functions as the Ace fake in the video. I would bet they both came from the same factory and even use the same PC board. For what it actually is, it does more or less what you’d expect it to. Quality is a different matter: our warrant return rate on BH’s is very low and I’m sure the same with the Ace. A Chinese manufacturer selling in the USA has little opportunity to deal with warranty issues and therefore doesn’t know whether or not they’re making junk. Having no contact with end user customers makes it difficult to learn how to make a better product.

As long as they don’t violate IP or trademark laws, it’s legal. Patents aren’t relevant to the low end machines, any patent that might have applied to them has long since expired. In other words, the typical imitators can’t be kept out of the USA. The USA market is becoming globalized and that means we USA manufacturers have new challenges.

–Dave J.

Posted by Dave J. on 6/5/2010, 11:00 am, in reply to “I too have had bad experiences with the HOTTER!!!”
There seems to be some confusion as to what I’ve said about coils and frequencies. The F75 & T2 coils are aligned on a test fixture which is literally that product operating at its normal operating frequency. Most of our searchcoils are aligned at a specific frequency which corresponds to the operating frequency of the product they’re used on.

Some searchcoils are of design and manufacture such that they are relatively broadband, and therefore can be aligned at one frequency and used at another, or can be used at multiple frequencies simultaneously.

A highly sensitive machine, whether analog or digital, is sensitive not only to the things you want (small or deep targets), it’s also sensitive to searchcoil imperfections which would go unnoticed on a less sensitive machine. Those “imperfections” don’t necessarily have anything to do with alignment, they can also be things like shielding, microphonics, etc. No searchcoil has perfect shielding or is completely free of microphonics. The further “hots” are pushed by the circuit, the more difficulty a company has making searchcoils good enough to keep imperfections below the threshold of noticeability.

This doesn’t have anything to do with whether the machine is analog or digital. Keith’s citing the Nautilus makes that point. It just happens that nowadays when a company spends money to make a machine “hot” they usually spend money on a microprocessor and software while they’re at it. The Naughty, Troy X-5, and Tejon were probably the last USA all-analog really hot machines. I don’t believe we’ll see any more.

–Dave J.

Posted by Dave J. on 6/5/2010, 7:31 pm, in reply to “Last analog machines”
The searchcoil issues of PI machines are rather different from those of VLF induction balance machines. A PI searchcoil must necessarily be wideband– narrowband is not an option.

Had there been the time and expertise to incorporate a main microprocessor in the TDI, it could have been a better machine than it already is. Meanwhile it is what it is, and it’s pretty darn good from what I hear. Haven’t swung one myself.

20 years ago during the development of the CZ platform, twice during that project I spent some time trying to figure out how to plug a microprocessor in there. Both times it turned out that the benefit to cost ratio didn’t warrant it. But this is 20 years later and it would be unthinkable to design a new multifrequency platform as an all-analog machine. Manufacturing cost would be too high, and there are too many things you can’t do in circuitry that you can and should do in software.

Microprocessors are even invading the low end. BH makes microprocessed target ID machines that retail for about $100: that platform dates from 2003. The BH Junior platform (approx. 2007) which generally retails in the $60 range was probably the last all-analog hobby metal detector platform of my career. If I had to do something like that today, there’d be a microprocessor in it. And that’s coming from an old-fashioned cut-his-teeth-on-vacuum-tubes “analog guru”.

–Dave J.

Re: Funny you mention the TDI Dave !! When will First Texas give us some sort of a P.I. Machine
Posted by Dave J. on 6/6/2010, 12:11 am, in reply to “Funny you mention the TDI Dave !! When will First Texas give us some sort of a P.I. Machine”
You may ask, Keith. And you’re right, “it” (whatever that is) is top secret. Don’t worry, I’m not offended– when nobody is curious what we’re up to, I’ll know we’ve become has-beens.

Nearly 100% of audio you hear through an electronic entertainment device, has been reduced to digital form at several steps along the way from sound in the air from the source, to sound your ear. Class D audio power amps are very common these days: they literally drive the speaker with a digital waveform that becomes analog only because of the frequency response limitations of the speaker system and your ear. Digital replicates Handel’s Messiah and Jimi Hendrix’s Star Spangled Banner– in hi-fi.

The assumptions that people are making here about analog and digital in recent posts relate to specific product implementations they’ve seen from the past, and don’t have anything to do with basic technology.

–Dave J.

Re: Thanks for the insight Dave! and thank’s for taking the time to come on
Posted by Dave J. on 6/6/2010, 10:33 pm, in reply to “Thanks for the insight Dave! and thank’s for taking the time to come on “
Keith, you said “I don’t know of any other engineer that would do so and do it uncloaked like your self…”

Hmmmm, Carl-NW sure sounds to me like Carl Moreland, engineering manager at White’s. You won’t see Carl and I arguing over very much because he is a very good engineer, we knew each other long before he went to work for White’s; and although White’s and FTP-Fisher are competitors, we are friendly terms.

The only sore point is that when I saw White’s hire Carl, I said, “darn, why the heck didn’t we think of that??!!”

I don’t think anyone in this industry has been as generous in sharing knowledge as Eric Foster on the “PI Classroom” forum on a certain other well-known metal detector forum site. Eric Foster is of course the primary engineer behind the White’s TDI which has already been mentioned in this thread.

–Dave J.

Re: Hey Dave I was paying you a compliment
Posted by Dave J. on 6/7/2010, 1:04 am, in reply to “Hey Dave I was paying you a compliment”
Yeah, I know, Keith, it was all intended as a compliment. Thank you.

But I had to put in a good word for Carl, too. For two reasons. First, because Carl deserves it. Second, because most people don’t believe things like that can happen, and I like to ruin such pessimistic beliefs.

–Dave J.

A personal tribute to Jim Lewellen
Posted by Dave J. on 5/31/2010, 1:03 pm, in reply to “Sad news: Jiim Lewellen…. retired CEO of Fisher Lab… “
I went to work for Jim on 9 Feb 81. I had virtually nothing in the way of credentials, so why he thought I could “do the job”, I don’t know. I’d like to think he somehow saw potential in me. But more likely of the engineers he interviewed I was the only one willing to move to Los Banos, which was then just a farming community out in the middle of nowhere.

As others have already said, Jim was a very decent chap, courteous, a gentleman, flexible, even-tempered, with quiet but strong sense of ethics and fairness. Without formality and without self-righteousness: it was just natural with him.

Jim provided direction of course, but pretty much let me do what I wanted to do. I often had “bootleg” projects going which he had not authorized, or which he had even discouraged, but he looked the other way while I spent time on them. Some of those “bootleg” projects eventually turned into products.

He also understood the value of research. Within weeks of being hired, I realized that we needed to understand how dirt influences metal detectors, and gradually put together a geophysics “dirt research” laboratory within Fisher. It eventually got to the point where I was in contact with world-famous rock and soil magnetics scientists and the learning went both ways. We are still relying on that foundational work that was done during the Lewellen era.

In product development, he allowed plenty of time to do field testing and to get things right. Once on the market, the products mostly stayed on the market for a long time. Several products we introduced in the 1980’s early 90’s are still in production with minor updates: the TW-6 (intro. approx. 1986)is still the industry standard utility 2-box locator.

I left Fisher in 1995 because of conflict with a new engineering manager. For Jim’s sake I hated to do it, but it was a situation that Jim even though he was CEO, didn’t have the ability to fix.

Working for Jim, I got more than just a job. With Fisher’s ability to actually manufacture and sell products I had designed, it was at Fisher that I developed a career. It’s a career that I’m still working at 29 years after Jim hired me. And thanks to First Texas Products’ acquisition of Fisher 4 years ago, some of those “designed during the Lewellen era” products are again putting food on my table.

Thank you, Jim Lewellen.

–Dave Johnson

Re: I heard that,
Posted by Dave J. on 5/25/2010, 3:00 am, in reply to “I heard that,”
I was told by an electronic component mfr’s rep who sells to both companies, that James is suffering from an undiagnosed ailment and was no longer able to participate in the operations of the company.

I hate to see that happen because I worked with James a few years back and really liked the guy.

If someone who knows him personally is reading this, please encourage James to contact me. I have been dealing with the medical establishment for 5 years over a disease that was supposed to have killed me (ALS) and the experience has taught me a lot. Maybe I can provide James some piece of information which will break his medical logjam and make it possible for him to be healthy again. A long shot, but one worth trying.

–Dave Johnson
915 633-8352

Re: Mark 1 25th anniversary:: Thanks George
Posted by Dave J. on 5/12/2010, 6:39 am, in reply to “Re: Mark 1 25th anniversary:: Thanks George”
I don’t know George personally, but I have a lot to thank him for.

George created what we here in El Paso call “the Payne circuit”, an ingenious method for doing target ID which I would never have discovered in a lifetime. He invented it for the leading bleeding edge of metal detector technology more than 2 decades ago, and the cost of manufacturing it with the technology and economies of scale available back then were probably part of the picture of the demise of the first Teknetics company.

But the Payne legacy lives on. The ashes of the original Teknetics company eventually wound up in the hands of one of the present capitalists. The design was simplified taking advantage of economies of scale and of advancements in the rest of the electronics industry. It became the foundation for mass marketed metal detectors.

I hope that George won’t get too upset that our proudest showpiece of what he gave birth to, is the Fisher F2. I’ll leave it up to other forums to say how good that product is and what its price point is. The high end of the market is now dominated by other technologies. But in the field of electronics, there is no shame in being able to say that one of the best products available on the market today is based on one you did more than 20 years ago.

Thanks, George.

–Dave Johnson
Chief Designer, FTP-Fisher

Re: White’s Coinmaster is awful!
Posted by Dave J. on 4/26/2010, 1:16 am, in reply to “White’s Coinmaster is awful!”
George, the Coinmaster has a well earned good reputation. It has even been knocked off by a Chinese manufacturer who retails in the USA, how’s that for flattery?

I can also tell you that there are places where mineralization is high enough that any VLF machine will perform poorly. I do not know if that’s how your terrain is. Mesabi taconite?

A penny at 3 inches deep, as a single solitary test, is not valid. There may be a nail half an inch away, or a magnetite hot rock. To know how a machine works in a particular area you have to be using it at its optimum settings for the prevailing conditions and for your particular style of hunting, evaluating it over numerous targets in comparison with other machines whose characteristics you are familiar with.

I express no opinion whether or not you got a dud, that can’t be determined one way or the other form your post. However I should point out that there are conditions under which a good machine (any good machine) will perform like crrap, and you shouldn’t judge the machine’s capability by what it does under a narrow set of conditions. A Coinmaster that air tests well is usually not defective and should do quite well under most conditions.

And, since I work for FTP-Fisher, I am duty bound to point out that the Coinmaster is not the only machine that when it air tests well will do a decent job under most conditions.

–Dave J.

Re: Counterfeit T2 s
Posted by Dave J. on 4/21/2010, 3:58 am, in reply to “Re: Counterfeit T2 s”
As a practical matter, what’s legal is almost irrelevant. Counterfeiting is a new metal detector industry challenge and some creativity will be needed in order to combat it.

The problem is industry-wide, not just our T2. It will be interesting to see if legitimate manufacturers will find ways to share information in order to meet the threat. As some of you know, I am a long-time advocate of cooperation between manufacturers on matters of mutual interest.

–Dave J.

Re: Counterfeit T2 s
Posted by Dave J. on 4/18/2010, 10:31 am, in reply to “Counterfeit T2 s”
There is a company (possibly more than one) in China that counterfeits metal detectors as well as doing knockoffs which are not literally counterfeit. (A counterfeit is a fake designed to be sold as the original real thing; a knockoff is in some sense a copy but not represented as the original.) They possibly do some original designs of their own as well. They have their own tooling. They advertise on Alibaba, a massive marketing website which is a favorite venue for shady Chinese businesses. Appropriately named, “Ali Baba and the Forty Thieves”.

There was a post here that the new Minelab model could be found on Alibaba, although I didn’t look there. I suppose someone in China is just reposting Minelab information, trolling for a wholesale buyer who can make it worthwhile to pay to tool up a counterfeit. A lot of original manufacturer website material is reposted on Alibaba, the obvious purpose of which is to advertise counterfeits. Hard to tell from the Alibaba advertisers whether they actually have product or not.

China is new to the concept of intellectual property and trademarking, and at this stage of their economic development there is not much incentive to bring their legal system and enforcement practice up to first world standards on this matter.

No telling what’ll be counterfeited next. One of the dangers of marketing a product (no, don’t ask me for a specific example) before it’s ready to ship is that a fast counterfeiter might actually hit the market with junk-in-a-box before the real thing is finally shipping.

To my knowledge no counterfeit product is shipped to the USA, the market here would “out” it in an instant and people could get hit with civil and perhaps even criminal penalties. Fakes are for markets where the customers are unfamiliar with the real thing. Some Chinese products sold here are non-counterfeit knockoffs of USA products, and occasionally they “get it right”. There are also some more or less original designs as well. …. As major manufacturer metal detector manufacturers’ designs depend increasingly on software function, copying becomes more difficult– you have to figure out what’s going on inside and then write your own code, a time-consuming process that requires considerable knowledge.

–Dave J.

Re: Coils and frequencies
Posted by Dave J. on 4/4/2010, 3:29 am, in reply to “Coils and frequencies”
Well, since several of my favorite people have posted in this thread, I suppose this is a good time to break my silence.

The beepering public wants to know what coils are interchangeable with what, and wishes there were a simple rule of thumb. Or maybe two or three good rules of thumb.

The most reliable rule of thumb is to check with the manufacturer of the metal detector in question what they believe works– which of course will be what they sell for that product. And, the manufacturer will get the answer right most of the time.

There are basically 10 parameters required for a searchcoil to be compatable with a particular beeper.

1. Transmitter inductance.

2. Transmitter shunt capacitance.

3. Transmitter resistance.

4. Receiver inductance.

5. Receiver shunt capacitance.

6. Reactive imbalance at the frequency that the detector operates at.

7. Resistive imbalance at the frequency that the detector operates at.

8. Compatible wiring diagram.

9. Other peculiarities unique to the searchcoil or the detector such as temperature sensors or loop coding resistors.

10. Loop connector compatibility.

Carl at White’s can probably think of a couple extra things I missed.

Some detector designs aren’t very picky about certain searchcoil parameters. Other designs are picky about just about everything. All these things involve tradeoffs between various performance and manufacturability considerations. Each engineer has their own perception of what the optimum tradeoffs are for different products, and the result is no industry standardization. Look at the bright side: if there was industry standardization, everything would use 2005 era Bounty Hunter searchcoils– which are good searchcoils, they’re used on the Fisher F4 and F2– but you can’t get a high end product out of ’em.

A year or two ago someone stuck a BH 4 inch searchcoil on a Fisher F5 and reported that it “worked”. Down here in El Paso we got a good chuckle out of that, because the question what would happen if you stuck a BH searchcoil on an F5 had never crossed our minds. So we checked it out. Yep, the thing sort of worked, but that was hardly the same as having an F5 compatible searchcoil.

–Dave Johnson
Chief Designer, FTP-Fisher

Re: Coils and frequencies
Posted by Dave J. on 4/5/2010, 10:12 am, in reply to “Re: Coils and frequencies”
The ten items I mentioned about searchcoil compatibility are physical things. They can’t be “transmitted”.

What a searchcoil with a cable can do, that a wireless one can’t, is to get the weight and the metal of circuitry and wires out of the searchcoil, and thus to provide for a metal detector which can accommodate different searchcoils and which has better ergonomics.

–Dave J.

Re: WOW! A new Minelab is on the way!
Posted by Dave J. on 4/17/2010, 3:01 am, in reply to “WOW! A new Minelab is on the way!”
Okay, enquiring minds want to know, where can we find this exciting news on a factory-traceable post?

Not that I’m skeptical– actually, I believe the whole thing. The question is, “should I?”.

The company I work for, has also been known to come out with products which were alleged minor improvements rather than giant leaps forward. Sometimes the alleged minor improvements hit the ground with both feet on four cups of coffee, and sometimes giant leaps forward hit face down not very far beyond the starting line. Neither the engineers nor the marketing dept. decides what a product actually turns out to be: it’s the customers who decide.

I like it that way!

–Dave J.
Jefe de diseno de detectores de metales en El Paso Tejas, Ciudad gemela la revolucion sin fin de las dos Americas

BTW, for those of you who don’t happen to know your history, about 160 years ago the USA mostly back East decided that the nation was destined by God Almighty to become a nation of two nations, and fought multiple wars on that premise. Thanks to the success of those wars, as a native-born alleged “anglo”, I have the privilege to live in the Latin American region of the USA.

This whole story is no abstraction for me, through the circumstances of fate it happens to be my family history. If you’ve read the plaque on the monument to the shrine of the Ninos Heroes in Mexico City and wondered who the “invaders” were, PM me, I’ll tell you.

Re: Dave.
Posted by Dave J. on 4/17/2010, 2:05 pm, in reply to “Dave.”
GB & G2 “guts” will be very similar.

–Dave J.

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