Advanced PI coils

[Aziz]

Mono AI PI Coil vs. Mono PI Coil

Hi all,

this is the co-axial stacked mono PI AI coil comparing it against the mono coil. The standard mono coil acts as the RX+ coil part after switch-off. Co-axial above (5, 7.1, and 10 inch) there is the RX- coil for the anti-interference feature. This is the Eric Foster's AI coil shown earlier.

Coil Comparison (Calculated Response Ratio to Reference Coil)
© 2012 by Aziz Ögüt. All Rights Reserved. 20-Dec-2012
Reference Coil: 300 µH Round Mono Loop Coil
		10" Mono Co-axial AI PI Coil (5 inch distance)	10" Mono Co-axial AI PI Coil (7.1 inch distance)	10" Mono Co-axial AI PI Coil (10 inch distance)
Target Depth [inch]	Target Depth [cm]	Relation to Reference	Relation to Reference	Relation to Reference
1	2,5	0,712	0,834	0,913
2	5,1	0,753	0,857	0,926
3	7,6	0,763	0,859	0,925
4	10,2	0,759	0,853	0,919
5	12,7	0,746	0,841	0,910
6	15,2	0,729	0,826	0,898
7	17,8	0,710	0,808	0,885
8	20,3	0,689	0,790	0,871
9	22,9	0,667	0,771	0,856
10	25,4	0,646	0,751	0,840
11	27,9	0,625	0,732	0,824
12	30,5	0,605	0,713	0,808
13	33,0	0,585	0,694	0,793
14	35,6	0,567	0,676	0,777
15	38,1	0,549	0,659	0,761
16	40,6	0,532	0,642	0,746
17	43,2	0,515	0,625	0,731
18	45,7	0,500	0,610	0,716
19	48,3	0,485	0,594	0,702
20	50,8	0,471	0,580	0,688
21	53,3	0,458	0,566	0,675
22	55,9	0,445	0,552	0,662
23	58,4	0,433	0,540	0,649
24	61,0	0,422	0,527	0,637
25	63,5	0,411	0,515	0,625
26	66,0	0,400	0,504	0,613
27	68,6	0,391	0,493	0,602
28	71,1	0,381	0,482	0,591
29	73,7	0,372	0,472	0,581
30	76,2	0,363	0,462	0,570

Cheers,
Aziz

[Aziz]

Bl00dy hell!!!,

I'm going to beat all VLF detectors...
It's quite difficult to make some bench testing with the loose coil assembly at the moment. But as far as I could see the detection depth on a 1 EUR coin, ... and it's sensitivity to small targets ...

I have used the center-tapped Tophat TX coil drive (=high power VLF) with an active RX amplifier this time.

I need a stable coil frame assembly.
I need a stable coil frame assembly.
I need a stable coil frame assembly.

It's time to make new world records...

Aziz

Hi all,

do you remember my posting above?

The calculated results and the observed real coil testing results confirms this. I have a vey sharp pin-pointing feature. And there is a higher sensitivity in the near detection zone too so I can detect small targets as well to a remarkable detection depth. And it goes deeeeeeeeeeeeeeeep, which I'm capable of to beat all the VLF detectors...
Ooooooops, probably not anymore. Damn it!, I shouldn't have published the results... Everybody can beat the existing metal detectors now.


I'm not finished yet.. stay tuned...
Aziz

[Tinkerer]

What's left over? I have made almost 3 dozens of coil simulations and I'm stil not finished yet.
The other coils will be added from time to time until the doomsday is stopping me doing this.

Ok, the co-axial stacked AI mono coil (the Eric Foster's coil in this thread), where the TX=RX+ (after switch-off) and above the RX- coil is placed coming soon.
The Davor-Sergey coil, ... coming soon too.

Cheers,
Aziz,
I'm so tired...

Great work, congratulations and many thanks.

How do you feel about the TANDEM COIL? Basically 2 concentric, coplanar IB coil assemblies side by side, in opposite phase. This should be good for AI as well as GB, if the signals of the 2 coil assemblies are processed as differential. Like a gradiometer.

[Aziz]

Great work, congratulations and many thanks.

How do you feel about the TANDEM COIL? Basically 2 concentric, coplanar IB coil assemblies side by side, in opposite phase. This should be good for AI as well as GB, if the signals of the 2 coil assemblies are processed as differential. Like a gradiometer.

You're welcome Tinkerer. All the calculated performance comparison figures are my Christmas gift to you all.

Tandem coil is also interesting. I'm thinking of coding my coil software to make few things more comfortable to me (less work). So I can make the figure-8 coil analysis as well.

All the trivial work first of course.

Cheers,
Aziz

--------------------------------------------------------------------------
PS to patent-trolls:
No! No! Don't do it! Don't do it bad guy! I'm going to **** you otherwise...

[Aziz]

The Davor-Sergey AI IB Coil (without CX)

Hi all,

this coil configuration inductively balances by setting the RX- coil apart from the co-planar region slightly (~20 mm).
I think, it won't disturb the coil architecture when it is slightly thicker due to coil arrangement. But it makes the coil design a bit simpler and easier to balance (two options - see below). The picture below is showing the RX+ radius factor of 1/sqrt(2) in an induction balanced state.

The 0.5 radius factor is getting slightly thicker. The co-axial balance distance is almost an inch wide (actually 25 mm in my model). But it performs a bit better of course.

I'll make the comparision for 0.71RX and 0.5RX and will add the compensation coil variant too (the CX coil part). If you see the CX naming, then you know, you need additionally the CX coil (which makes the coil more complex of course).



Isn't that fine, that you don't need a CX coil?

Cheers,
Aziz

[Aziz]

The Davor-Sergey AI IB Coil vs. Mono Coil

This is the coil configuration above compared against a mono coil. I didn't make the coil configuration with the compensation coil (CX) and we can neglect it as it won't do much better. The following figures give you the performance comparision regards to mono coil and SNR. You can see, that the target response losses are significant at depth. But the EMI noise rejection should be good as the RX+ and RX- coils won't be much apart and you can ramp up the gain with a low noise amplifier to compesate for losses. Notice, this is an IB and AI coil.

Coil Comparison (Calculated Response Ratio to Reference Coil)
© 2012 by Aziz Ögüt. All Rights Reserved. 20-Dec-2012
Reference Coil: 300 µH Round Mono Loop Coil
		10" Davor-Sergey AI IB Coil (0.71RX)	10" Davor-Sergey AI IB Coil (0.5RX)
Target Depth [inch]	Target Depth [cm]	Relation to Reference	Relation to Reference
1	2,5	1,759	5,895
2	5,1	1,475	3,924
3	7,6	1,165	2,540
4	10,2	0,916	1,736
5	12,7	0,733	1,266
6	15,2	0,601	0,974
7	17,8	0,503	0,781
8	20,3	0,430	0,648
9	22,9	0,373	0,550
10	25,4	0,329	0,476
11	27,9	0,293	0,419
12	30,5	0,263	0,373
13	33,0	0,239	0,336
14	35,6	0,219	0,305
15	38,1	0,201	0,279
16	40,6	0,186	0,257
17	43,2	0,173	0,238
18	45,7	0,161	0,222
19	48,3	0,151	0,207
20	50,8	0,142	0,195
21	53,3	0,134	0,183
22	55,9	0,127	0,173
23	58,4	0,121	0,164
24	61,0	0,115	0,156
25	63,5	0,109	0,148
26	66,0	0,104	0,141
27	68,6	0,100	0,135
28	71,1	0,096	0,129
29	73,7	0,092	0,124
30	76,2	0,088	0,119

Cheers,
Aziz

[Aziz]

Hi all, .. .. oh sh1t!, the doomsday is coming .. the doomsday is coming...
I'm going to a34j´405lkjfg982756uldfkgiz$§"%§asdf540^72j$%§$&"§ &!&!%&"§$!§$....

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The current universe has been crashed.
Please enter '[B]42[/B]' to restart the universe.
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Please enter '[B]42[/B]' to restart the universe.
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Reset
Restarting the universe now ..
Loading the world V2.0 ..
Loading .. please wait..
..............................
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Done.
Aziz: Hello World! 
Aziz: This is Aziz V2.0. 
Aziz: Are you Ok?
Aziz: Hello? Hellooooooo! Is anybody there????

Soo funny. Sorry, but I couldn't resist..

[Aziz]

Hi all,

hey, I've survived the doomsday.
(To your bad fortune, you have to bear with me and my coil sims now. )

--------------------- serious mode ------------------------

Ok, let's modify the Davor-Sergey coil a bit to decrease the ground noise (magnetic viscosity effects etc.) and make it a bit thinner (co-axial thickness). That could be made, If we're going to make the RX- smaller (0.8 ) and RX+ accordingly 0.5RX- (0.4). Note: No compensation coil (CX) favoured.
Let's see, what comes out... and whether an IB condition can be made too..
Aziz

[Davor]

Yes, I'm very curious about the outcome. In such configuration Rx coils would both be far apart from Tx so even the capacitive couplings will not make any influence - no Cx and all.

[Aziz]

Yes, I'm very curious about the outcome. In such configuration Rx coils would both be far apart from Tx so even the capacitive couplings will not make any influence - no Cx and all.

Unfortunately, the idea failed right now. The coil gets thicker (now 30 mm at least).
Compensation coil is required to make it thinner. I'll try more ideas ..
Aziz

[Aziz]

Unfortunately, the idea failed right now. The coil gets thicker (now 30 mm at least).
Compensation coil is required to make it thinner. I'll try more ideas ..
Aziz

No, the above were the best I could get. All other trials produce a lot of zero's (super insensitive).

Anyone with a good idea?
Aziz

[PATCHES JUNIOR]

Anyone with a good idea?
Aziz

Seems like all your great ideas are getting shot down. Especially your bad language. Can you not go a month without the filth?

[Ferric Toes]

Going back to the Eric Foster type coaxial stacked coil which I used in the early 1980's in my PPD1 detector, there is another way of operating it. The centre coil is the TX, but is also RX1 so that it operates as a standard mono. This is fed to its own RX channel, sampled, differentially integrated and amplified such as to give an "all metal" signal. In the PPD1 this gave an audio only signal. RX2 and RX3 were similar size RX coils held in electronic balance. This fed a discriminator channel, sampled and integrated in the same way but displayed on a centre zero meter. The signal sample however was 4uS after TX switch ON. The differential earth's field sample was shared with the "all metal" channel. For non-ferrous metal the meter swung right and for ferrous it swung left. In air, this discrimination was very reliable, even steel washers and bottle caps showed as ferrous. This detector was primarily for beach searching and had no ground balance, hence inland it had limited use.

I used a Garrett 7in diameter stacked coil former as used in one of their VLF detectors at the time. The TX/RX1 acted as a standard 7in mono, and the RX2, RX3 balance coils were just for discrimination, but I was able to get almost the same detection range from the disc channel as the mono channel even though the spacing of RX2 and RX3 was only about 1.5in. The "all metal" channel had a comparator that switched on the disc. meter circuit when a few mV had been exceeded, so that noise did not appear on the meter in no signal conditions.

I will find the schematic of the disc channel and auto balance circuit in due course and post it on the Forum, unless it is there already - have to check.

Just another way of using the EF stacked coil, and with a good GB arrangement would have lots of potential. It would be interesting to try, say, 10in TX/RX1 with 7in RX2, RX3 for a nice coil shape that thins out toward the edge.

Eric.

[Davor]

No, the above were the best I could get. All other trials produce a lot of zero's (super insensitive).

Anyone with a good idea?
Aziz

The original setup with Cx was fine. Without Cx a bit more interesting. Don't count it as failure, you just found a way not to do it

BTW, seeing PJ poisoning the well, you just know you are on the right track. A real ground balancing coil would surely make some more advanced rigs a bit less palatable considering their notoriously unpalatable price tags.

[Davor]

In air, this discrimination was very reliable, even steel washers and bottle caps showed as ferrous. This detector was primarily for beach searching and had no ground balance, hence inland it had limited use.

Eric, I'm about to try some more ideas in synthesizing a ferrous target for use with Spice. My current attempt is only half way there and I'd appreciate features to look after with ferrous targets excited by PI pulses so that I can verify Spice "targets" to qualify as Fe. Your solutions are very popular and vastly copied, yet my simulations showed that every delayed sampling is prone to Fe-NFe uncertainty and not so perfect discrimination, given the right combination of targets. Am I missing something?

Could you please teach us a bit on this, perhaps in a separate topic?