Does Anyone Want To Open This Can Of Worms?

[Bohemia Miner]

I recently had a conversation with a well-known Electronic Prospector about companies, technology, etc.

He stated that D/D coils go deeper than Concentric. 

If that's the case, why have all the PI Gold Hunters resorted to Mono coils?

Bruce Candy and not Eric Foster invented Pulse Induction.  

The story I heard was Eric Foster first approached Whites with the PI Technology and was turned down.  He then went to Minelab and the rest is History.

 

Minelab sold Garrett the Technology to make the Axiom.

I'd like to give Garrett a little more credit than that!

 

Does anybody want to chime in?  

[hawkeye]

No thanks, not going down these rabbit holes.

[Steve Herschbach]

DD coils can go deeper than mono under the right conditions, or they would not exist. But not all conditions. Mono can also go deeper than DD. It’s a matter of right tool for the job, with ground conditions determining which works best.

Bruce Candy did not invent pulse induction, and Eric Foster had nothing to do directly with Bruce’s innovations, so both those statements are wrong. It’s probably more accurate to think that Bruce built on top of Eric’s prior work. I’m sure he was aware of Eric’s work since Eric did PI before Bruce. Bruce added dual channel ground balancing later on. It’s probable neither of them invented the basic first pulse induction circuit. George Payne possibly? Patent sleuths now have something to chase down… not going to bother myself.

Whites did license the TDI from Eric, but that was at a much later date. The TDI is just a Goldscan with a few tweaks in a different box.

And Minelab did not sell Garrett technology for the Axiom. It’s based on the prior ATX, which is based on the Infinium. People in metal detecting often try to talk one company down by saying they licensed this or that from somebody else. Though it’s very common for companies to incorporate or cross license technology first used by others. That's how technology progresses.. things build one to the other. Almost all detectors incorporate concepts first thought of by George Payne. There is not one company selling detectors today that do not borrow or build on technology innovated by others.

[klunker]

 Worms should always be purchased in a box and not a can.  Persons whose opinion is otherwise probably lack my experience and expertise.  

[LuckyLundy]

Steve, is more than correct “Under the Right Conditions”. Back in the old GPX days one of my Favorite Minelab Coils was the 12x15 DD.  This coil worked the best in Mild Dirt and Peaked after the first sprinkles of Fall Rains.  During some Drought Winters it didn’t come off my Detector.  Under rated by many, but a deadly coil to the few.  
 

Rick

[Bohemia Miner]

Thanks, Steve!  One hears a lot of information and claims in this industry.  It's sometimes hard to determine what' true and what's not.

I've recently read Charles Garrett's book regarding hunting in "Sand & Sea" and the Sea Hunter PI was available at its publishing in 1990.  I figured Garrett's PI progression was as you stated in your reply but maybe starting with this model, then the infinium, etc.

I recently read somewhere that White's invented Multi-Frequency but was told by Jimmy Sierra that they had to pay royalties to Minelab for the DFX.  If I'm not mistaken, Compass had a Dual Frequency machine before that.

They are definately borrowing from each other now!

[Steve Herschbach]

The DFX dual frequency tech was licensed from Minelab. It was used first in the Beachhunter ID because there was a time limit on the license requiring a machine in X amount of time. The DFX was not quite ready so the Beachhunter ID employed the license first and is essentially a stripped down DFX.

Switchable frequency machines have been around for ages and that is not the same as simultaneous multifrequency. The Compass X200 could be switched from 6 kHz to 13.77 kHz - one or the other. The DFX is either 3 kHz or 15 kHz - or both at the same time. So I would call the DFX dual frequency but not the Compass.

I do not consider switchable frequency to be multi frequency. Multi frequency always referred to simultaneous multiple frequencies, not machines that can be switched to run different frequencies, but only one at any given time. But then Nokta had to screw it all up by calling the switchable frequency detectors multifrequency. So now people have to specify simultaneous multi frequency SMF to differentiate, when before we all knew that was exactly what was being meant by multifrequency. A detector that can simply be switched from this frequency to that frequency is NOT a multifrequency detector. It is a single frequency detector that lets you pick frequencies. XP knows this and never called the Deus 1 a multifrequency detector and good on them for that! The Deus 2 - that's multifrequency.

[Bohemia Miner]

Steve, when I used the term "Dual Frequency", I wasn't referring to SMF.  I know the Compasses were "selectable", one or the other.  Didn't they (Compass) have one that had a lower frequency for coins and a high one for gold nuggets?  Something like 7 and 50, making it a dual-purpose machine.

Thanks!

[Steve Herschbach]

I was clarifying terms in general. When you say dual frequency to me you are referring to a dual frequency SMF whether you intend that or not. Because that's what that always meant until recently when people started tossing terms around and blurring the meanings. Which is why I made the clarifications.

I mentioned the X-200. Compass never had anything higher than around 14 kHz except for 52 kHz in the failed AU 52 and AU 2000. The AU 2000 may be the one you are thinking of, but it never really was made other than a few units before Compass went under. The AU 2000 could be switched from 14 kHz to 52 kHz. The AU units I tried were too unstable to use really, probably more the coils than anything, as I don't think Compass mastered how to make a high frequency coil right before the clock ran out.

There is more to a detector than just the frequency and all these old machines do not hold a candle to current technology.

[GB_Amateur]

4 hours ago, Steve Herschbach said:

It’s probable neither (Bruce Candy nor Eric Foster) invented the basic first pulse induction circuit. George Payne possibly? Patent sleuths now have something to chase down… not going to bother myself.

Geotech folks have already done the legwork:

Note the 1972 date (and its submission 18 months earlier), inventors, all apparently with Western Electric (part of AT&T at that time).  However, also look at the references of earlier patents.  The 1963 one (which I couldn't find specifically) is mentioned in a 2010 patent submitted by John Earle of White's:

That sounds to me as if Barringer (as early as 1963) is describing the modern technique.  Also keep in mind that things can be documented well before patents, in scientific literature, so a deeper dive there could be even more revealing.