ARE MINELAB PI'S SUPERIOR?

[montana]

AZnugget Bob. I obviously missed something somewhere> I wasn't making reference to anything you said when I told the scam box story. I was just pointing out how things aren't always what they seem on a "test bench" . On another note, you mentioned the 3 lb. patch. It is once again producing gold after all these years. The big ones seem to be long gone, but the GPX4000 is picking out lots of missed small ones. Some remarkably shallow, some remarkably deep for their size. The dense clay layer seems to limit depth of nuggets on this patch and some others at Rich Hill. You can see places where some have skimmed off 8 or 10 iches of ground hoping to find lots of gold deeper , but I doubt that this is the case. That clay layer is often as effective as true bedrock at stopping nuggets from working deeper into the earth with only the occasional one finding its way beyond 18 inches or so. This was graphicly demonstrated on the Roadrunner claims a couple of weeks ago. The club tried a push on a patch where many nuggets had been found in the top 6 inches or so . They pushed several fairly large spots down a few inches into the clay layer and had a huge outing where hundreds of members eagerly expected the mother lode of nuggets to be unearthed. I was told that a whopping total of 3 nuggets were found for all the effort. This happens often in desert placers. The deeper you go the poorer it gets.----Bob

[Steve Herschbach]

Steve, I have heard several people state that VLF's either find or have found more gold than PI's

If you consider that VLF's have been around a lot longer and that by sales statistics they probably outnumber PI's 10 to 1 would this not explain that?

Let me put it this way: If you send out a search party with ten people with PI's and send out a search party with a hundred people with VLF's which search party will be most successful?

Don't forget to give the VLF search party a fifteen year head start.

AzNuggetBob

Hi AzNuggetBob,

I'm not sure what your point is. That lots of people have been using lots of VLFs for a long time and finding lots of gold? Yeah, I'd agree to that. Seems like an argument for owning a VLF unit to me.

But I was talking about Alaska right now. Last year, the year before, and I'm sure this year coming up. For the money any one of several $700 VLF nugget detectors do the job well for many people up here. Minelab SD/GP sales in Alaska are in the dozens each year compared to sales of White's GMT, MXT, Tesoro Lobos, and Fisher Gold Bug 2s in the hundreds. While this does mean there are simply more VLF units up here, it also means that people are buying them because their buddy has one and it does the job.

As I said, there is an area south of Anchorage larger than most states that has low mineralization and relatively small gold. A Gold Bug 2 or White's GMT will generally serve better than any Minelab in this area. The Minelab "true believers" have a hard time accepting this, but it is the simple fact. Virtually nobody around here uses a Minelab in the Prince William Sound area. It is not that they would not work. It is that for all the extra money spent you will not find any more gold than a VLF, and miss tiny bits a GB2 hits with ease. I've heard the old "I do not care about little gold" excuse a thousand times, but when I'm sitting there digging piece after piece of gold next to you that you are unable to find with a unit costing 6 times more it does have an impact.

Ganes Creek Alaska has consistently rewarded users of VLF units more than Minelab users because Minelab units, including the Eureka Gold, have poor iron discrimination. There is so much iron junk at Ganes Creek the user of a Minelab is simply worn down from digging junk, not to mention all the time wasted. I consider many who visited Ganes Creek with me a few years ago with their Minelabs friends, and so I do not rub it in, but the fact is the local boys easily trounced the visitors. I heard every excuse possible for why that was, including that we cheated, but the simple fact is that Ganes Creek does not favor Minelab units, plain and simple. Of course some people have used Minelab units at Ganes Creek and found gold. What I'm talking about is what has worked best over several years for lots of people. My buddy Bernie was on of the last people there last fall, and found over two pounds of gold in two weeks with a White's MXT.

So it is not about a hundred VLF guys versus 10 PI guys. It is about me meeting you at Ganes Creek, you with a GPX-4000 and me with a White's MXT. I'm pretty confidant I'd get more gold than you. Or let's go to numerous local creeks in my area, you with a GPX-4000 and me with a Gold Bug 2. Again, I'm pretty confidant I'd get more gold than you.

I'm not ragging on Minelab. I use their units almost exclusively at Moore Creek, and I will be using a GPX-4000 more than any other unit this summer. But if all I had was a VLF unit I could and would still go out and find gold. Lots of gold.

At Moore Creek summer before last I took the guys down the creek. I was cutting trail with my chainsaw, and hauled a Gold Bug 2 with 6" coil along. I spent most of my time cutting trail, but when I got tired I'd take a break and detect awhile with the Gold Bug 2. I found more nuggets with the Gold Bug 2 in a week than some of the Minelab guys, even given that fact that the Minelab units are veatly superior at Moore Creek. I'm expert with a VLF to the point that I can do better than a Minelab novice in many cases, no matter the conditions. Experience counts.

I have no doubt that for most the areas you guys hunt down south and for the type of gold you are hunting Minelabs are the way to go. I pay attention to the locals, and if I was to visit you guys I'd be using my Minelab. But if you ever come hunt with me and I tell you you'd be better off with a VLF you'd best pay attention. VLF units are not yet obsolete.

In fact, I think I'll be going to Ganes Creek this fall, and I'm thinking out of all the new units on the market the new Fisher F75 offers the potential to be the best Ganes Creek unit released since the MXT. Very light weight, superb balance, and excellent iron disc... all what you need at Ganes Creek.

I have at least eight detectors right now, each with a specific task it excels at. Maybe I'll live to see the days when one machine can suit me for all tasks, but I doubt it. Building a unit to be exceptionally good at one task usually means it suffers at other tasks. Computer processing and the ability to program machines in software may help change that, however, and so maybe the day of the super do it all machine is closer than I think.

Steve Herschbach

[AZNuggetBob]

Montana I will say that I must agree with you on that Pulse Devil. To much hype for something that only exists in theory. I have been hearing the same thing from many people. I went back to the three pound patch a few weeks ago. I only took one but there are more no dought. I have not had the chance to swing the new 4000 but I have been seeing what Rob has been taking out of old hammered patches with it. AzNuggetBob

Maybe he will let me borrow it? Hey Rob, Just Kidding.

[montana]

AznuggetBob. I think I was the first one on the 3lb patch with the GPX 4000. There were only a couple of fresh holes on it at first this season. Now it is pretty well cratered again. I took lots of small ones off it and I know of dozens of other small ones that have been found there with the GPX4000. It was well worth going over again. Most people had long ago given up on it.----Bob

[Reg]

Hi John,

I am betting you thought I meant what happens to the current feeding the tank circuit and not what was happening inside the tank circuit itself. Actually, I wanted to know what the actual tank circuit current was doing or more specifically, what was happening in the coil windings.

This was to show that although a VLF doesn't appear to be powerful since it can be run on small batteries, the actual current in the coil can be much higher.

So, John, do we agree on the following?

Doesn't the current within the parallel tank circuit rise to maximum, but the current feeding the tank circuit drop to minimum? That is why they adjust the tuning by watching the dip in the current feeding the tank circuit. However, the actual current in the tank, in theory will approach infinity or maximum with minimum input at resonance.

Here is a quote from Wikipedia.

Applications of resonance effect

1. Most common application is tuning. For example, when we tune a radio to a particular station, the LC circuits are set at resonance for that particular carrier frequency.

2. A series resonant circuit provides voltage magnification.

3. A parallel resonant circuit provides current magnification.

4. A parallel resonant circuit can be used as load impedance in output circuits of RF amplifiers. Due to high impedance, the gain of amplifier is maximum at resonant frequency.

5. A parallel resonant circuit can be used in induction heating.

For those interested, here is an example of what happens in a parallel circuit. Now, in this case, I simply copied an example that had already been calculated.

You can see it at;

http://www.play-hookey.com/ac_theory/ac_lc_parallel.html

----------

The Circuit

A parallel LC circuit.

In the schematic diagram shown to the right, we show a parallel circuit containing an ideal inductance and an ideal capacitance connected in parallel with each other and with an ideal signal voltage source. For consistency, we will use the same example values that we used when examining the series LC circuit. Thus,

* VAC = 10 vrms.

* f = 1 MHz. (ω = 6283185.3 rad/sec)

* L = 150 µh. (XL = 942.4778 Ω)

* C = 220 pf. (XC = 723.43156 Ω)

According to Ohm's Law:

iL = vL/XL = 10/942.4778 = 0.01061033 = 10.61033 mA.

iC = vC/XC = 10/723.43156 = 0.013823008 = 13.823008 mA.

If we measure the current provided by the source, we find that it is 3.2126777 mA — the difference between iL and iC.

The question to ask about this circuit, then, is, "Where does the extra current in both L and C come from, and where does it go?"

---------

Ok, I am too lazy to create my own circuit but copied one where the calculations had already been done.

The calculations above indicate the source only supplies 3 ma but the current in the inductor is 10 ma. So, the circuit only draws minimal current from the source but still has heavier current in the coil.

Now, apply this same concept to a VLF and you can have high currents in the coil but only draw low current from the battery.

Right John?

Reg

[AZNuggetBob]

Hi AzNuggetBob,

I'm not sure what your point is. That lots of people have been using lots of VLFs for a long time and finding lots of gold? Yeah, I'd agree to that. Seems like an argument for owning a VLF unit to me.

But I was talking about Alaska right now. Last year, the year before, and I'm sure this year coming up. For the money any one of several $700 VLF nugget detectors do the job well for many people up here. Minelab SD/GP sales in Alaska are in the dozens each year compared to sales of White's GMT, MXT, Tesoro Lobos, and Fisher Gold Bug 2s in the hundreds. While this does mean there are simply more VLF units up here, it also means that people are buying them because their buddy has one and it does the job.

As I said, there is an area south of Anchorage larger than most states that has low mineralization and relatively small gold. A Gold Bug 2 or White's GMT will generally serve better than any Minelab in this area. The Minelab "true believers" have a hard time accepting this, but it is the simple fact. Virtually nobody around here uses a Minelab in the Prince William Sound area. It is not that they would not work. It is that for all the extra money spent you will not find any more gold than a VLF, and miss tiny bits a GB2 hits with ease. I've heard the old "I do not care about little gold" excuse a thousand times, but when I'm sitting there digging piece after piece of gold next to you that you are unable to find with a unit costing 6 times more it does have an impact.

Ganes Creek Alaska has consistently rewarded users of VLF units more than Minelab users because Minelab units, including the Eureka Gold, have poor iron discrimination. There is so much iron junk at Ganes Creek the user of a Minelab is simply worn down from digging junk, not to mention all the time wasted. I consider many who visited Ganes Creek with me a few years ago with their Minelabs friends, and so I do not rub it in, but the fact is the local boys easily trounced the visitors. I heard every excuse possible for why that was, including that we cheated, but the simple fact is that Ganes Creek does not favor Minelab units, plain and simple. Of course some people have used Minelab units at Ganes Creek and found gold. What I'm talking about is what has worked best over several years for lots of people. My buddy Bernie was on of the last people there last fall, and found over two pounds of gold in two weeks with a White's MXT.

So it is not about a hundred VLF guys versus 10 PI guys. It is about me meeting you at Ganes Creek, you with a GPX-4000 and me with a White's MXT. I'm pretty confidant I'd get more gold than you. Or let's go to numerous local creeks in my area, you with a GPX-4000 and me with a Gold Bug 2. Again, I'm pretty confidant I'd get more gold than you.

I'm not ragging on Minelab. I use their units almost exclusively at Moore Creek, and I will be using a GPX-4000 more than any other unit this summer. But if all I had was a VLF unit I could and would still go out and find gold. Lots of gold.

At Moore Creek summer before last I took the guys down the creek. I was cutting trail with my chainsaw, and hauled a Gold Bug 2 with 6" coil along. I spent most of my time cutting trail, but when I got tired I'd take a break and detect awhile with the Gold Bug 2. I found more nuggets with the Gold Bug 2 in a week than some of the Minelab guys, even given that fact that the Minelab units are veatly superior at Moore Creek. I'm expert with a VLF to the point that I can do better than a Minelab novice in many cases, no matter the conditions. Experience counts.

I have no doubt that for most the areas you guys hunt down south and for the type of gold you are hunting Minelabs are the way to go. I pay attention to the locals, and if I was to visit you guys I'd be using my Minelab. But if you ever come hunt with me and I tell you you'd be better off with a VLF you'd best pay attention. VLF units are not yet obsolete.

In fact, I think I'll be going to Ganes Creek this fall, and I'm thinking out of all the new units on the market the new Fisher F75 offers the potential to be the best Ganes Creek unit released since the MXT. Very light weight, superb balance, and excellent iron disc... all what you need at Ganes Creek.

I have at least eight detectors right now, each with a specific task it excels at. Maybe I'll live to see the days when one machine can suit me for all tasks, but I doubt it. Building a unit to be exceptionally good at one task usually means it suffers at other tasks. Computer processing and the ability to program machines in software may help change that, however, and so maybe the day of the super do it all machine is closer than I think.

Steve Herschbach

Hi Steve I have two VLF's in my arsenal, Right tool for right job. Ive heard alot about Moore creek and Gains creek much of the ground is flipped. Which usualy means deep garbage.Not unlike the 24k pushes here in Az. If I were going to hunt there on the pile pushes I would probably hall ass through there with a odd freqency VLF to avoid all the minelab cross talk and pick up the easy ones and return later and go after the deep ones with a Minelab PI. Using the right tool in a given situation. No offense intended. AzNuggetBob

I will say one thing that so far no one has addressed is the one thing about the Gold Bug 2 and other high freqency VLF"s although they pick up very small gold very well they also pick up shotgun shot very well. We have lots of it here.

[Reg]

Hi AZNuggetBob,

Thanks for the information about Salee and his video.

Yes, adjusting the ground balance will cause all VLF's I have ever seen to see the nugget under the magnetite (hematite also). Adjust the ground balance such that the detector balances to the rock or even slightly positive and the problem goes away. However, if people try the test I mentioned, they will find it doesn't take much of a ground balance adjustment to go from not being able to detect the nugget to being able to get a good signal.

The problem lies in the fact, most people will generally go back to the regular ground balance setting and when they do, any nugget around any rock containing magnetite can easily be missed. Now, hunt in an area where the ground has a lot of such rocks and it is very easy to miss nuggets.

I am just hoping more VLF owners become aware of this and keep it in mind when hunting. It can make a difference over the long run.

My objective of making a point of this issue is to inform those who might not know of the problem.

Reg

[AZNuggetBob]

Hi Reg I agree, Good point,One thing I forgot to mention is the detector in auto-tune will revert back to normal ground balance on its own. to work the detector must be rebalanced over every target which sounds like a pain but sometimes its the only way to hunt some diffacult patches. AzNuggetBob

[montana]

Reg and AZnugget Bob. The problem that I found with adjusting the GB to the point to where the nugget would be picked up rather than the the ironstone, was that then the ground in between the hotrocks was so noisy that I couldn't stand to detect with it that way. The problem was even more pronounced in some of our western soils where the Ironstones give extremely strong signals and the ground in between is very neutral . The more the difference, the more difficult it becomes. The rapid change from one to another is enough to drive you batty. Here again, it can be demonstrated to work , but is it in reality something that most people can do and be succesful with. I couldn't make it work to my satisfaction and always returned to normal GB away from an ironstone. It all became irrelevant to me soon after I got my hands on a PI. Once I went through the VLF withdrawls , I was rarely even tempted to pick one up again. The few times I did try them again were very short in duration. Once it sunk into my head that PIs weren't just for large deep gold, and I learned the tricks to finding small gold with them , there just didn't seem to ever be any reason to go backward.----Bob

[Wirechief]

Hi John,

I am betting you thought I meant what happens to the current feeding the tank circuit and not what was happening inside the tank circuit itself. Actually, I wanted to know what the actual tank circuit current was doing or more specifically, what was happening in the coil windings.

This was to show that although a VLF doesn't appear to be powerful since it can be run on small batteries, the actual current in the coil can be much higher.

So, John, do we agree on the following?

Doesn't the current within the parallel tank circuit rise to maximum, but the current feeding the tank circuit drop to minimum? That is why they adjust the tuning by watching the dip in the current feeding the tank circuit. However, the actual current in the tank, in theory will approach infinity or maximum with minimum input at resonance.

Yes this is right Reg and that is why I tune for a dip in the plate current on my HF amplifier and I will see maximum fire in the wire. But I see what you were getting at Reg. This has been a very good point Reg and you are right my friend.

John Tomlinson,CET

Here is a quote from Wikipedia.

Applications of resonance effect

1. Most common application is tuning. For example, when we tune a radio to a particular station, the LC circuits are set at resonance for that particular carrier frequency.

2. A series resonant circuit provides voltage magnification.

3. A parallel resonant circuit provides current magnification.

4. A parallel resonant circuit can be used as load impedance in output circuits of RF amplifiers. Due to high impedance, the gain of amplifier is maximum at resonant frequency.

5. A parallel resonant circuit can be used in induction heating.

For those interested, here is an example of what happens in a parallel circuit. Now, in this case, I simply copied an example that had already been calculated.

You can see it at;

http://www.play-hookey.com/ac_theory/ac_lc_parallel.html

----------

The Circuit

A parallel LC circuit.

In the schematic diagram shown to the right, we show a parallel circuit containing an ideal inductance and an ideal capacitance connected in parallel with each other and with an ideal signal voltage source. For consistency, we will use the same example values that we used when examining the series LC circuit. Thus,

* VAC = 10 vrms.

* f = 1 MHz. (ω = 6283185.3 rad/sec)

* L = 150 µh. (XL = 942.4778 Ω)

* C = 220 pf. (XC = 723.43156 Ω)

According to Ohm's Law:

iL = vL/XL = 10/942.4778 = 0.01061033 = 10.61033 mA.

iC = vC/XC = 10/723.43156 = 0.013823008 = 13.823008 mA.

If we measure the current provided by the source, we find that it is 3.2126777 mA — the difference between iL and iC.

The question to ask about this circuit, then, is, "Where does the extra current in both L and C come from, and where does it go?"

---------

Ok, I am too lazy to create my own circuit but copied one where the calculations had already been done.

The calculations above indicate the source only supplies 3 ma but the current in the inductor is 10 ma. So, the circuit only draws minimal current from the source but still has heavier current in the coil.

Now, apply this same concept to a VLF and you can have high currents in the coil but only draw low current from the battery.

Right John?

Reg

[Steve Herschbach]

Hi Steve I have two VLF's in my arsenal, Right tool for right job. Ive heard alot about Moore creek and Gains creek much of the ground is flipped. Which usualy means deep garbage.Not unlike the 24k pushes here in Az. If I were going to hunt there on the pile pushes I would probably hall ass through there with a odd freqency VLF to avoid all the minelab cross talk and pick up the easy ones and return later and go after the deep ones with a Minelab PI. Using the right tool in a given situation. No offense intended. AzNuggetBob

I will say one thing that so far no one has addressed is the one thing about the Gold Bug 2 and other high freqency VLF"s although they pick up very small gold very well they also pick up shotgun shot very well. We have lots of it here.

Hi Bob,

No offense taken, and no offense intended!!

If I'm finding bullets or shot I try to look at it as a good sign. Probably means gold left to be found. It is when I cannot find any non-ferrous targets at all that I start getting worried!

I can't wait to get my hands on a Pulse Devil. I'm cautiously optimistic. Normally I'd be more skeptical, but I've talked to Dave, and one thing I can tell you is he is completely sure of his design. No big sales pitch, just a guy really sure the unit will do what he says it will. The discussion we had was refreshing and left me thinking this is more than just talk. It is going to be an interesting year in detectors indeed.

Steve Herschbach

[Reg]

Hi Montana,

I agree that when you adjust the ground balance to the point you don't miss nuggets, then the detector generally gets very noisy. This is clearly one of the big reasons PI's became popular to begin with.

Now, most VLF's designed for gold allow for a very fast autotune which helps considerably. Unfortunately, most people do not like to use it since it does cause a reduction in depth of detection.

You are also correct, the PI basically eliminates this problem so it is not practical to go back to the VLF in many areas.

Now, I also agree with Steve H. when he mentions there are places where the VLF will shine also.

Getting back to the magnetite problem, is this something that can be improved upon with newer designs? Of course it can. The trick is to get those who design the things to use them more and then allow them to develop the necessary changes to overcome the problem, or at least, minimize it. Whether that ever happens or not is a different story. Unfortunately, most design engineers don't use the detectors they design.

This same problem with magnetite holds true for the discrimination mode on the VLF's. Most will fail to detect gold as a good target if there is magnetite around and near the good target. In fact, this can be a big problem if the disc mode is used to determine whether to dig or not and the detector is adjusted to minimize the rock problem in the all metal mode. Since the two circuits are independent the all metal can be adjusted to minimize the problem but the discrimination mode still be affected.

Reg

[AZNuggetBob]

Hi Bob,

No offense taken, and no offense intended!!

If I'm finding bullets or shot I try to look at it as a good sign. Probably means gold left to be found. It is when I cannot find any non-ferrous targets at all that I start getting worried!

I can't wait to get my hands on a Pulse Devil. I'm cautiously optimistic. Normally I'd be more skeptical, but I've talked to Dave, and one thing I can tell you is he is completely sure of his design. No big sales pitch, just a guy really sure the unit will do what he says it will. The discussion we had was refreshing and left me thinking this is more than just talk. It is going to be an interesting year in detectors indeed.

Steve Herschbach

Hi Steve I feel the same way about the lead. Its when its painfuly quiet that you know your really going to need to put your ear to the ground. AzNuggetBob

[Reg]

Hi Steve,

You stated;

"I can't wait to get my hands on a Pulse Devil. I'm cautiously optimistic. Normally I'd be more skeptical, but I've talked to Dave, and one thing I can tell you is he is completely sure of his design. No big sales pitch, just a guy really sure the unit will do what he says it will. The discussion we had was refreshing and left me thinking this is more than just talk. It is going to be an interesting year in detectors indeed.

Steve Herschbach"

As for me, I have been in communication with Dave for a very long time now, but from a technical standpoint. We have traded emails on the technical aspects for a very long time. In fact it goes back to when he decided on the logo PD logo and that was quite some time back.

From a technical point of view, I know some of what Dave is doing and why he has confidence in his design. There are things he is doing that should clearly make his design work well.

Now, I am not sure just what is the minimum delay on his unit is, but when it comes to detecting the small stuff, one really needs to reduce the delay before sampling.

Now, to deviate a little for a moment, some time back John Blennert used to brag about his "invisible nuggets". For those unfamiliar, John had found quite a few nuggets in the Greaterville area that appeared to be invisible when using a ML. One of his favorite games was to bet people as whether they could detect the nuggets or not. Well, when taking a quick look at the nuggets, it was very easy to think John didn't know what he was talking about.

As it turns out, John did know and the nuggets, even though some were quite large (fingernail size and larger), the PI simply wouldn't detect them. John mentioned he didn't think any PI could detect them. So, I asked for a couple and he was nice enough to send a couple to me and then a couple to Eric Foster.

Well, when I received mine and initially tested them, I was surprised just like all the others who had seen the nuggets. The only way I could detect them was to rub them across the coil of my detector.

So, I set out to figure out a way to modify my PI so it would be able to "see" the invisible nuggets.

Now, in the process of trying to figure out the solution to the problem, it became apparent that the only way to detect the really small stuff was to use a different type coil than the mono. Simply stated, the mono wouldn't allow the sampling time to be reduced enough to see many of the nuggets. For me, this left either the concentric or the DD design. Since I was already using the DD design to reduce the ground signal, I continued with it and ultimately accomplished my goal.

In the meantime, Dave selected the concentric because his design would allow the larger concentric transmit to be used, which meant more depth when compared with the DD. Also, he reduced his delay time even more than I have on my unit which should allow his detector to do a better job on the small stuff than mine does.

Now, with either coil, it is possible to reduce the sample time significantly. This sample time reduction makes it possible for the PI to approach being able to detect extremely small gold just like many of the VLF's.

The other affect of using a shorter delay is the simple fact, the signal is much greater to begin with. So, one already starts out with an advantage.

One other need for either a concentric or a DD design is because of the extra sampling needed for discrimination. Using the technique Dave does, again, the mono coil was not an option.

Now, as for the discrimination feature, is it a feature that will reduce the depth or have any other negative impact? Nope, this feature is, in some ways, independent. Is the design totally alien and unproven? Nope, the basic idea was implemented many years ago by Eric Foster. Unfortunately, at the time it was used, a couple of techniques were not thought of.

Those of you who have been around metal detectors long enough to remember the old VLFF/TR's and the problems with the discrimination modes on those detectors will have a better idea of what I am talking about. Under ideal ground conditions, the original PI and the TR design worked quite well. Unfortunately, when the ground conditions became severe, the disc mode on both failed to perform as needed. Ironically, both the VLF/TR and the earlier discriminating PI designed by Eric Foster failed for very similar reasons. The ground signal simply was the culprit.

Ultimately, the VLF/TR was replaced by the new motion detectors thanks to George Payne. Now, Dave is accomplishing basically the same on the PI. Now, is Dave accomplishing the same by using the motion techniques used in a motion detector to accomplish the goal? Nope, he is using something a little different. Will it work? Yep, I have confidence in it.

Here is the interesting part. Just as the disc mode has no impact on the VLF motion detector when it comes to the overall depth, the disc mode on Dave's PI will be very similar. The disc mode is basically independent from the main PI mode. One should consider both modes to be independent of each other. Also, just as the disc mode on the VLF goes almost as deep as the all metal mode, the same will hold true on the PI design.

Now, will the disc mode be perfect? Nope, but none are now. It will, be head and shoulders above what is out there on the PI's now. Like Dave says, it will be much more like the disc mode on a VLF.

Now, I just hope Dave doesn't get too mad at me for divulging this information. I also hopes he finishes and meets me in AZ in a couple of weeks.

Reg

[montana]

Reg. You just said it perfectly. The design engineer usually has no concept of what we run into out in the goldfeilds. He knows there are minerals in the ground that he has to counteract and probably knows of or has samples of some type of hot rock, but oh my does he know how many different types of hotrocks are out there? Does he know how many different minerals are in the ground, salts, alkali, copper, graphite, etc. besides the iron oxides. If he compensates for one does he make matters worse on others? Do you know if Dave has any really good detectorists working with him? I cannot believe that anyone can take a detector from the drawing board to the final product without a lot of trial and error testing on many different types of ground by very experienced detectorists , and I have heard no mention of this being attempted or even being in the plans. It just seems to be, I designed this, the physics are right , I will do a couple of tests, and I will sell it. There is no way in hell I would buy a completely new detector without knowing who did the testing, what his qualifications are, and how extensive was the testing. Joe Blow from Arkansas who found a few nuggets once just ain't good enough to convince me. And to hell with the controlled test plots. I long ago decided that there wasn't near enough info there. It's going to be a hard sell.----Bob

[Reg]

Hi Montana,

First, I can't tell you who Dave has working with him. I do know from emails and conversations he has been at this a long time and is an active user of detectors himself. In fact, he took a prototype to Alaska on one of the tours given by Steve H last year, I believe.

Now, I am going to deviate some for a moment again. As we know, ML has designed several different versions of their PI starting with the SD 2000 and now the latest the 4000. So, how did we get from point A to point B and why? Some think much of the evolution of this was planned or maybe some units were placed into production well before they should have been.

Maybe some of that is true, but as one who has been working on my own version and knowing the pitfalls that go along with design changes, I can say that no amount of design can overcome all of what nature can throw at us. Just when we think we have a handle on it, along comes something else that wasn't seen before. In other words, a product is developed and it appears to work well. Now, get it in the field for a while and sure enough, a new "wart" will appear.

So, much of the evolution of the ML has been a product of dissolving the warts discovered in the previous model.

The old adage of "for every action there is a reaction" is extremely true in the development of a detector. Overcome one problem and the design can easily create a new problem. In most cases, it isn't visible for some time either.

Unfortunately, if we waited until a design was perfected before we took it to market, we would still be waiting for the wheel, let alone for the car.

I certainly understand Dave's desire for all to be perfect before he introduces his PD, but I would like to see the unit out in the field and find the "hidden" warts. Will there be some? Yep, it has happened with every detector I know of. I also believe most will be trivial also.

As for test plots, I disagree. It is impossible to design a detector out in the field and a lot of testing has to be done. The trick is to make the test plot as realistic as possible and not simply a couple of items buried in the ground.

Now, Dave has had a lot of strange rocks sent his way so he can develop a pseudo OZ ground condition. He also has a lot of red clay common to gold producing areas where he lives, so he does have some field locations that are more along the lines of what a person will run into when gold hunting.

You are right, the final design should be because of the result of field testing and that is what I have expressed to Dave.

Now, I will toss this at you ML owners. Why condemn any detector just because it doesn't measure up in your opinion, to ML's best when it first comes out? Minelab has taken, what, 15 years or so to get to this latest model? Why didn't they build it at day one instead of so many years later. So, why expect anyone else to match it at day one? The simple fact is, ML couldn't do it on day one, why should anyone else be required to?

If we expand on what you guys say, shouldn't we condemn ML for building all previous models they have built because the new 4000 has now made them "junk" because of its new and wonderful standard? So, are we supposed to call the 3500's and earlier models ML's junky POS designs?

(Now, that should generate a few posts)

ROB, SEE WHAT YOU STARTED!!!! HE HE HE

Reg

[Wirechief]

Hi Reg, also the inductor(coil) can be seen as storing current and the capacitor of course stores voltage. If it was a perfect world this charge and discharge cycle in the parallel LC circuit would be self sustaining. But it isn't and will play out or ring to a stop eventually. But there is a peak in the current in the tank coil that is quite high at a certain point in this cycle and that is what you are looking at. So yes it is a really cool phenomenem isn't it? Ok CU later Reg.

John Tomlinson,CET

John's Detectors

[Steve Herschbach]

Hi Reg,

Thanks, great info.

Dave visited Ganes Creek a couple years ago with an early PD prototype. He did find a nice nugget with it, which at Ganes is an accomplishment in itself. I was not there at the time however. I do know that Dave has been getting out and testing this in the field, however.

I do not blame you for being skeptical Bob. And surely, most people should wait and see until reports from various and trusted sources come back on the Pulse Devil. But you are selling Dave short if you think the Pulse Devil is going straight from the drawing board to production with no testing.

It would be off the mark to think the Pulse Devil is intended to be a Minelab killer. It is simply a new detector that will be good at some things and not so good at others. I am more interested in the idea that it could be the first pulse induction detector suitable for general coin detecting. The market for coins, jewelry, and relics vastly exceeds the nugget hunting market, and so if the Pulse Devil proves to be a good multipurpose PI unit it could be more successful than units designed purely to hunt nuggets. The White's MXT is a huge success for just that reason.

Anyway, time will tell. Not too long ago a relatively unknown company produced a weird detector called the SD 2000. It took some time for people to figure out why anyone would want such an expensive and bulky unit. It also was far from a perfect unit, but it became evident it offered new capability to the detectorist at large. But my hope is that people keep pushing the envelope and developing new units. I do not know how we will be looking back a year from now on the Pulse Devil, but I do appreciate the fact that Dave is at least trying to give us something new.

Steve Herschbach

[prospectinginoz]

Montana I will say that I must agree with you on that Pulse Devil. To much hype for something that only exists in theory.

AzNuggetBob

The Pd does NOT just exist in theory. In fact over the 6 years or so that Dave has been involved in the project he has built about a dozen Pulse Devils each time refining and testing different ideas and circuit topologies. A recent version of the Pulse Devil was used in Alaska and Dave found a 1/2 oz nugget with it right next to a huge piece of iron junk. The PD able to tell him that there were 2 targets present iron and non iron. When the 4000 came out the bar was raised by ML. Dave's reaction was ok now I have to jump even higher. Dave does not want to come out with a Pi detector that is just a 3rd rate pale shadow of the 4000. He does not not want to even try and match the 4000 in all aspects, he wants to beat it in ALL aspects. The final version of the PD is nearly complete and I expect will be on its way to OZ soon for field testing when the software programming is completed and the very exhaustive bench testing is completed.

Now the PD could be the greatest Pi flop of all time. But on the other hand what do think you consumer reaction ,would be if its performance exceeds the 4000 in all aspects, ie it has true ferrous/non ferrous discrimination, is weather proof,is lighter and smaller than the 4000 even with ithe Pulse Devil's self contained batteries and 1 watt high efficency speaker, has coils that are probably 1/2 the weight of ML or after market coils, will be upgradeable by changing components on the board or at worst replacing the board ( no more upgrades by having to buy a new model!),may be more sensitive to small gold than the 4000 and will go much deeper on large targets(mega nuggets in Oz or relics etc for treasure hunters),has a coin/ relic mode with adjustable discrimination up to pull tabs, has better EM immunity than the 4000 and will come onto the market at perhaps 1/2 the price of the 4000!

Yes it all could be a pipe dream but so far at least the bench testing with 8" coils is most encouraging. The acid test for the PD is coming soon when it is confronted with our horrible oz soils and the ground at Rich Hill. The testing in Oz will tell the story as the PD will stand or fall on how it handles our ground (and in Vic we also have some horrible EM noise). And I can assure you that we have some ground which I have extensive data on from an earlier Pi project that will test the PD to its limits.

All the testing results will also be in the public domain and hence available for everyone to see, the good, the bad and the ugly! What other Pi manufacturer has put their pre release testing results and methods in the public domain? Certainly not ML!

Doug

[dave wiseman]

Great stuff fellows,though I'm too thick to grasp much of the info you provide.Does anyone have any info or thoughts on a PI that White's may come out with,or is it all a rumor?......Dave

[grubstake]

Dave, this guy up here in Mariposa, Gerry Edwards. Says they are coming out with one, with very good Discrimination, I'm not sure when or whats its going to be called, but if it works up here in this ground, it should handle anything. I have had many guys up here, they all agree this is very hard ground to detecting, with anything but a DD coil. Although the 4000 seems better on it with a mono than the other models. But we will have to see. The ground in Mariposa, makes the desert look like a kids sand box, as far as being hot. Grubstake

[Rattlesnake Jim]

Great stuff fellows,though I'm too thick to grasp much of the info you provide.Does anyone have any info or thoughts on a PI that White's may come out with,or is it all a rumor?......Dave

Dave, I'm pretty sure one is in the works!

[dave wiseman]

Thanks Gary and Rattlesnake Jim........Dave

[prospectinginoz]

Dave, I'm pretty sure one is in the works!

The info about Whites is correct. They are coming out with a discriminating Pi.The circuit is based on the design of of a well known Pi identity. That's all I can say.

Doug

[dave wiseman]

You guys in OZ always seem to be 5 steps ahead of everyone else,with infgo and product......Dave