field test unit no 001 "model T"

[Paul99]

Mr. Heenan adamantly denied the existence of eddy currents.

Agreed, he didn't acknowledge eddy currents.

I read his posts for a while for the entertainment value, but I don't recall he proposed anything like this.

He was examining and measuring the transmit and spike/flyback currents. The transmit is basically the same as flyback during abrupt transitions.

[moodz]

Agreed, he didn't acknowledge eddy currents.



He was examining and measuring the transmit and spike/flyback currents. The transmit is basically the same as flyback during abrupt transitions.

Thats like saying lets use antigravity to power spaceships .... does that mean I have now invented antigravity ? Are you able to quote a post or more substantial information ( eg patent ) where a method of doing this is described ?

[robby_h]

John Heenan argued that eddy currents don't exist and said a pi detector instead measures changes to the coil's properties caused by a metal object. This obviously includes changes to the coil current. He also argued that pulsing a coil to generate a high voltage pulse just to measure the changes in the spike is a waste of time because we get the same result during the pulse on-time, therefore we could measure changes to the coil's properties when just transmitting a continuous low current square wave. He did both.

The old PI classroom has numerous posts from novices who noticed how a metal object alters the coil's properties, ie, the spike's shape, tx shape, coil current and inductance, and some actually thought they had discovered something new when in fact it is something any engineer would predict without ever building a circuit. We can't call this a discovery because it is predictable.

Although some text says otherwise, traditional pulse induction does not measure the affect the target has on the spike's decay time or shape. If it did then PI would have no advantage over VLF and it would also have more problems to solve than VLF.

PI science is very mature now. I think it best to ask why others aren't using a particular method instead of naively assuming you have discovered something new.

[Carl-NC]

PI science is very mature now.

I would completely disagree with this.

[moodz]

John Heenan argued that eddy currents don't exist and said a pi detector instead measures changes to the coil's properties caused by a metal object. This obviously includes changes to the coil current. He also argued that pulsing a coil to generate a high voltage pulse just to measure the changes in the spike is a waste of time because we get the same result during the pulse on-time, therefore we could measure changes to the coil's properties when just transmitting a continuous low current square wave. He did both.

The old PI classroom has numerous posts from novices who noticed how a metal object alters the coil's properties, ie, the spike's shape, tx shape, coil current and inductance, and some actually thought they had discovered something new when in fact it is something any engineer would predict without ever building a circuit. We can't call this a discovery because it is predictable.

Although some text says otherwise, traditional pulse induction does not measure the affect the target has on the spike's decay time or shape. If it did then PI would have no advantage over VLF and it would also have more problems to solve than VLF.

PI science is very mature now. I think it best to ask why others aren't using a particular method instead of naively assuming you have discovered something new.

1. As you say "PI science is very mature now" .... Eddy currents do exist ... nuff said. John Heenan is entitled to his opinion.
2. I dont measure changes in the spike current or voltage or changes in the coil inductance.
3. New discoveries are not predictable or they would not be discoveries but be called "confirmations" or something similiar.
4. Not sure how you are comparing the spike decay time or shape to VLF .... but as I said I dont measure the spike decay time or shape.
5. Golly .... thats a leap ... because you say "PI science is very mature now" .. therefore you have proved nothing new can be discovered about it. ???
6. People are not using my method .... because obviously it has not been invented till now ... so I dont have to ask them.

[Silver Dollar]

Looks like John had to duke it out with conventional PI proponents ...

http://en.wikipedia.org/wiki/John_C._Heenan

[Paul99]

Looks like John had to duke it out with conventional PI proponents ...

http://en.wikipedia.org/wiki/John_C._Heenan

I thought John was the Archbishop of Westminster, and was relying on Divine Intervention to get his metal detector working.

http://en.wikipedia.org/wiki/John_Heenan_(bishop)

John did have high hopes for his detector. Here is a link to archived data from his web site....

http://web.archive.org/web/201307182...tp://zgus.com/

[PATCHES JUNIOR]

NO ONE has asked for any money in relation to this detector .. and the post says nothing about ground balance ... nothing about gold detection ... nothing about minelab and the 1000 gain you are talking about is completely out of context ... SO CHECK YOUR FACTS OR YOUR EYEGLASSES.

I never said "you" said this. If you read it again, I said Doug said this. So I guess we both need new glasses. And as far as Minelab, Doug never said Minelab directly. But who else would Doug try to discredit Moodz? And Doug is trying to get blokes to invest in your detector. And he DID SAY it would be a 1000 times better than the current offerings available. And you say no ground balance circuit in your detector. Read your post!!!!

[Carl-NC]

And Doug is trying to get blokes to invest in your detector.

Actually, Mr. X is someone else.

[robby_h]

1. As you say "PI science is very mature now" .... Eddy currents do exist ... nuff said. John Heenan is entitled to his opinion.
2. I dont measure changes in the spike current or voltage or changes in the coil inductance.
3. New discoveries are not predictable or they would not be discoveries but be called "confirmations" or something similiar.
4. Not sure how you are comparing the spike decay time or shape to VLF .... but as I said I dont measure the spike decay time or shape.
5. Golly .... thats a leap ... because you say "PI science is very mature now" .. therefore you have proved nothing new can be discovered about it. ???
6. People are not using my method .... because obviously it has not been invented till now ... so I dont have to ask them.

As I said, I think it best to ask why others aren't using a particular method instead of assuming you have discovered something new.

I suppose it all depends on what you call a discovery. It could be something you didn't know but is well known to others.

Re Post 866 of this thread, you posted something very similar in 2009 here http://www.findmall.com/read.php?34,920760,page=1

That was almost 5 years ago and in recent posts on an Oz forum you say "it may have shortcomings" and needs "a lot of field testing". It would make more sense if you prove the concept before declaring it a major advance in detector design.

http://www.geotech1.com/forums/showt...025#post157025

Your pictures (post #340) show a grossly under damped waveform and picture three shows what we would expect to see when a non-ferrous target is presented to an under damped coil. The apparent phase shift though shown and highlighted in picture four is an illusion caused by an incorrect trigger, ie, you triggered off the trailing edge instead of the leading edge.

With this mistake corrected, it should then be obvious that the spike decays faster for non-ferrous objects and decays slower for ferrous objects, exactly as we would expect. The problem though is that highly susceptible material such as magnetite has the same affect as a ferrous object and will completely overwhelm any small change caused by a target at depth and you can't apply traditional GB to your waveform because it is heavily contaminated with the x component that we deliberately avoid in traditional designs.

And your definition of "damped" is different to the industry's definition. If Eric Foster said he had the spike damped in 8 usecs then most people here would assume he meant the spike had decayed to 0 volts in 8 usecs. You say you can sample at 1.8 usecs in one instance and at 4 usecs in another but the waveform is still settling somewhere off the page. This would be a disaster if we attempted to apply traditional sampling at the times you mention.

In Post 866 of this thread you mention period C, supposedly decaying for some 100s of microseconds but this decay doesn't exist in traditional PI where the the spike has ideally settled to effectively 0 volts before sampling begins.

Your automatic self switching rx switch also seems to be a bit iffy. http://www.geotech1.com/forums/showt...130#post179130
Picture at
http://www.geotech1.com/forums/attac...7&d=1381835423

You said elsewhere that this switch makes 6 patents that use front end switches obsolete but how is this possible when it must be followed by a conventional switch in order to work??? Connect any of the popular opamps directly to M2 and your switch turns on and stays on resulting in a cooked opamp. Wouldn't it be best to iron out these problems before declaring it a major achievement??

[mickstv]

http://www.geotech1.com/forums/attac...7&d=1381835423

Connect any of the popular opamps directly to M2 and your switch turns on and stays on resulting in a cooked opamp. Wouldn't it be best to iron out these problems before declaring it a major achievement??

I actually tested that circuit some time back, using a NE5534 then a lower noise OPA1611, connected directly to the output of the M2 fet Both IC's survived the experience.

[Paul99]

I actually tested that circuit some time back, using a NE5534 then a lower noise OPA1611, connected directly to the output of the M2 fet Both IC's survived the experience.

As a matter of interest, mickstv, and before you commit yourself any further, what was the spike voltage in your case, and did you stick to the same voltages and component values? Ask yourself what would be the simplest mod you could make to Moodz's switch to ensure M2 stays on permanently.

[mickstv]

As a matter of interest, mickstv, and before you commit yourself any further, what was the spike voltage in your case, and did you stick to the same voltages and component values? Ask yourself what would be the simplest mod you could make to Moodz's switch to ensure M2 stays on permanently.

First of all I would like to say I'm not having a go at anyone here. I only posted here an impartial comment re the fact the circuit worked for me. Although I don't use it in my detector now, I just use the micro to control the blocking fet.

I didn't use D2 or D9 so the flyback was past 600v. I also changed R1 to a 3.3k. The voltage used was 6v TX and 12v on the gate of M2.

[Paul99]

First of all I would like to say I'm not having a go at anyone here. I only posted here an impartial comment re the fact the circuit worked for me. Although I don't use it in my detector now, I just use the micro to control the blocking fet.

I didn't use D2 or D9 so the flyback was past 600v. I also changed R1 to a 3.3k. The voltage used was 6v TX and 12v on the gate of M2.

G'Day mickstv, as a matter of interest, what do you reckon would be the simplest mod you could make to Moodz's switch to ensure M2 stays on permanently?

[mickstv]

G'Day mickstv, as a matter of interest, what do you reckon would be the simplest mod you could make to Moodz's switch to ensure M2 stays on permanently?

Have you tested the circuit yourself ?


Like I said before I only tested it, to see if it worked and thats all.