Advanced PI coils

[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

[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]

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/ols/auspat/quickSearch.do?queryString=metal+detector&resultsPerPage

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

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]

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

[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

[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.

[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]

Here is top coil removed.

Eric.

[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.

[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

[Aziz]

Round TX, Double-D figure-8 RX, AI PI Coil Added

Hi all,

I am referring to the post #335 (6666's wish). This is a 10 inch round TX PI coil, having the RX+ and RX- as figure-8 double-d coil (not overlapped) sitting inside the TX coil, as big as possible (3-4 mm edge space to give the coil bundle some space to fit inside the TX coil). RX+ (RX- identical but opposite winding direction) windings turn increased to have the same level of EMI noise induction as the 300 µH 10" round coil (reference coil). So this coil is SNR compensated.

This is the comparison graph at additional gain of x10 (see 10" Round TX, Double-D figure-8 RX - AI PI Coil):





This is the performance relation to the reference coil (no additional gain):

Coil Comparison (Calculated Response Ratio to Reference Coil)
© 2012 by Aziz Ögüt. All Rights Reserved. 25-Jan-2013
Reference Coil: 300 µH Round Mono Loop Coil
		10" Round TX, Double-D figure-8 RX - AI PI Coil
Target Depth [inch]	Target Depth [cm]	Relation to Reference
1	2,5	2,694
2	5,1	2,744
3	7,6	1,905
4	10,2	1,357
5	12,7	1,032
6	15,2	0,827
7	17,8	0,691
8	20,3	0,590
9	22,9	0,518
10	25,4	0,459
11	27,9	0,414
12	30,5	0,377
13	33,0	0,345
14	35,6	0,319
15	38,1	0,297
16	40,6	0,277
17	43,2	0,260
18	45,7	0,245
19	48,3	0,231
20	50,8	0,220
21	53,3	0,209
22	55,9	0,199
23	58,4	0,190
24	61,0	0,182
25	63,5	0,175
26	66,0	0,168
27	68,6	0,161
28	71,1	0,155
29	73,7	0,150
30	76,2	0,145

Cheers,
Aziz

[mickstv]

EMI reduction and counterbalance, I like it.

[Mechanic]

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

[Mechanic]

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