Advanced PI coils

[Aziz]

Hi Guys,

Well perhaps I should get my self some shares in "MadLabs Inc."(c)(tm)(r)" I'm not the best with math, but my missus thinks I'm mad, in fact, I think I could be just a bit mad however it works well, very well!

No target subtraction, just emi reduction and it is quite forgiving. I can almost get the 25" mono quiet at my house, it will be a dream while out bush. I might even be able to use a smaller coil for the emi coil to make it all a bit lighter, but even as it is, the detector is still quite usable

Cheers Mick


Possible "MadLabs Inc."(c)(tm)(r) participant

Hi Mick,

I love your madness and your easy playing around crazy ideas. You would fit into the mad company well.

(Although, the idea isn't new - one recent ML patent trying to cover it. But the claims were very broad written, that it even tries to lock the prior art coil configurations. )

Indeed, PI machines are forgiving a lot in such configurations. The farther away the EMI coil from the main coil, to less the EMI noise rejection ratio regards to near distant EMI sources. But the less target response as well.

But for far distant EMI noise sources, both coils should induce almost the same amount of EMI, which should be significantly cancelled.

Just make it work and try it in the gold fields. I would love to hear how it works.

Cheers,
Aziz

[Ferric Toes]

HI Aziz,

Try this, standard mono coil on the ground(25") and at the other end of the detector handle about 1M behind the operator another mono coil parallel to the ground about 1.5m from the ground. The coil behind the operator is used to cancel/reduce emi and is just a standard coil, 300uh. The emi coil will be a smaller coil, 18 or 16". and will have the same self resosnace as the main mono coil. The emi is subtracted in the electronics of the front end.

This should reduce emi making the use of the larger mono coil much more pleasant. Unfortunately both coils will not always be parallel, so the reduction will vary a bit, but this should be better than just a standard mono...... Whatcha think? I'm going to give this a bash on the weekend.

Cheers Mick

This is very quiet and works well in noisy areas. You can crank up the gain too. These coils are light and the differential setup is not too cumbersome to use. However, in quiet EMI areas I take the top coil off.

Eric.

[Ferric Toes]

Here is top coil removed.

Eric.

[Midas]

This is very quiet and works well in noisy areas. You can crank up the gain too. These coils are light and the differential setup is not too cumbersome to use. However, in quiet EMI areas I take the top coil off.

Eric.

That seems to make sense which makes me wonder, Aziz how is it that you are able to makes such definitive performance comparisons between AI and other coil types, does it not depend on exactly how much environmental noise there is? Or perhaps more specifically the ratio of environmental noise to self generated noise. I would expect that when environmental noise is already significantly less than self generated noise AI designs won't allow you to raise the gain much at all.


Midas

[Ferric Toes]

I thought of this:

Ex US Army mine detector modified for diving use circa 1970. Must have been IB and not sure if each RX has a TX or one TX around the edge.


Picture credit, Research, Search and Salvage, FLA.

[Aziz]

That seems to make sense which makes me wonder, Aziz how is it that you are able to makes such definitive performance comparisons between AI and other coil types, does it not depend on exactly how much environmental noise there is? Or perhaps more specifically the ratio of environmental noise to self generated noise. I would expect that when environmental noise is already significantly less than self generated noise AI designs won't allow you to raise the gain much at all.

Midas

Oh well, it must has to do with my medically certified extraordinary super dooper high MQ level (the "Majik quotient" level - ooops - I mean the "Madness quotient" level of course). *LOL*

What was the question again?
The internal noise isn't taken into account and does not help in the coil comparison as well. We are comparing bananas and other bananas. Not apples and bananas or chickens.

Of course, you are limitted by the internal noise (e.g. amplifier noise and other noise resources). So you can't crank up the gain as much as you would like to do it.

Some AI configurations does not allow much EMI noise rejection ratio. It depends on its configuration and other factors of course. But if you gain some rejection ratio, you can use the gain factor to rise the gain of the amplifier. It will compensate the target response losses either.

There is always EMI noise! You can't shield it.
(And your internal noise may even exceed the EMI noise too. WTF! I've told ya to use the ultra low noise amps!!! Ain't I?)

Aziz

[Aziz]

This is very quiet and works well in noisy areas. You can crank up the gain too. These coils are light and the differential setup is not too cumbersome to use. However, in quiet EMI areas I take the top coil off.

Eric.

Eric, get ready to be taken into court by (evil) ML and their ridiculous trivial patent (lodged but not certified - but blamed by me! Shame on this trial. ).
*LOL*
Aziz

[Ferric Toes]

Eric, get ready to be taken into court by (evil) ML and their ridiculous trivial patent (lodged but not certified - but blamed by me! Shame on this trial. ).
*LOL*
Aziz

What patent is that? I have used this type of differential coil since 1970's and can prove it. Didn't Corbyn also use it in his detector around the same time?

Eric.

[Aziz]

What patent is that? I have used this type of differential coil since 1970's and can prove it. Didn't Corbyn also use it in his detector around the same time?

Eric.

AU patent 2011100475 or 2011100476 (or both, can't remember the evil trivial patents).
(BTW, the patent has no merit and is very trivial. It shows again, what Greedlab is trying. Hey ML!, don't be evil! )

Have a look here (and goto the mentioned patents):
http://pericles.ipaustralia.gov.au/o...resultsPerPage

Should be visible on first or second page or so. And you can download the documents.

Aziz

[Davor]

Ex US Army mine detector modified for diving use circa 1970. Must have been IB and not sure if each RX has a TX or one TX around the edge.
Picture credit, Research, Search and Salvage, FLA.

I'm obviously not original, but I still wish to see it's performance. I can't believe someone already thought of using this exact configuration for diving. I'm positively amazed!

Aziz, please try this one ...

[Aziz]

I'm obviously not original, but I still wish to see it's performance. I can't believe someone already thought of using this exact configuration for diving. I'm positively amazed!

Aziz, please try this one ...

No, forget it. It's obvious, that it is a loser coil. The one Eric has shown should do it better due to large TX coil.
And the one I've done recently has only two RX coil parts (half RX+, half RX-) and is showing you how it is performing.
BTW, it would cause too much work for nothing.
Come up with a better idea (ground-breaking idea most welcomed!!!). It should be comparable to our coils too.

Aziz

[Sergey_P]

[Aziz]

Do you have a ground-breaking coil idea? But I only accept the mathematical description of the coils to avoid the misunderstandings.
Look here, like this:
http://www.wolframalpha.com/input/?i=PSY+curve
(see all the sine terms.. )

But that's not enough. I expect a three-dimensional description ( x(t), y(t), z(t) )

Ok?

Aziz

PS: Just kidding..

[Ferric Toes]

I'm obviously not original, but I still wish to see it's performance. I can't believe someone already thought of using this exact configuration for diving. I'm positively amazed!

Aziz, please try this one ...

There is even one on ebay http://www.ebay.co.uk/itm/COOL-MILIT...ht_1799wt_1161

Eric.

[Ferric Toes]

Mine detector is AN/PSS/11 and it is outer TX with 4 x RX. Lots of info on Google.

Eric.