Advanced PI coils

[Aziz]

Believe me or not , Aziz , but the "world best coil technology" is just the simple monocoil with additional balance circuit ...

No! Don't give up quickly mate.

There must be left over at least one big coil invention to the smartest guy (or girl). I'm just waiting for the guy, who is giving or kicking off the crucial coil idea. Comeon!, don't be evil. Let the cat out of the bag now.


Aziz

[Aziz]

The Spiral Mono PI Coil?

Ok, let's continue with the spiral mono PI coil now... (requiring more processing time however)
I'll begin the spiral at 0.5 times diameter and end at 1.0 times diameter units.
(Before you quickly run into the patent office, wait, wait!, it's prior art... *LOL* )

How is that spiral coil comparing to the equivalent mono coil regards to SNR?

(Anyone want to bet? My betting office has been opened right now. )
Aziz

[Ferric Toes]

Ok, let's continue with the spiral mono PI coil now... (requiring more processing time however)
I'll begin the spiral at 0.5 times diameter and end at 1.0 times diameter units.
(Before you quickly run into the patent office, wait, wait!, it's prior art... *LOL* )

How is that spiral coil comparing to the equivalent mono coil regards to SNR?

(Anyone want to bet? My betting office has been opened right now. )
Aziz

I'm not a betting man, but at a guess I would say that it is the same as a normal mono of mean diameter 0.75. Its detection range can't be as good, so for an object at the limit of detection for 1DU the SNR is all noise and no signal for the spiral coil. You need to specify what sort of noise, what type of object, and position of object on the coil axis. Best to use a spherical object at least 1/10th of mean coil diameter, so that the 6th power law applies for distances greater than the mean radius, and no orientation problems. All coils I have seen, shielded or NC have a NSR, not SNR. The signal is lifted out of the noise by synchronous processing and averaging and only then do we have a SNR.

Would not the Dual Field coil have a similar performance? That's what your calculations for the DF would suggest.

Eric.

[Orbit]

Give something concrete without can be or may not be !!!

[Orbit]

H2O+H20=H2O???? V=S:T ==> S=VxT ==> T=S:V S !!

[Aziz]

...
Would not the Dual Field coil have a similar performance? That's what your calculations for the DF would suggest.
...

Hi Eric,

the Dual-Field coil can be considered as a first approximation of a spiral mono PI coil (provided that, both coil parts have the same number of turns count).

A Tri-Field coil a second best approximation (0.5, 0.75, 1.0 diameter unit).
Continue with the splitting and it becomes the spiral coil at the end.

Notice, the coil comparision between the Dual Field and the mono coil was a direct coil comparison and the SNR wasn't taken into account on the Dual Field coil (just normalized to 300 µH). As we know, small coils with small coil flux area do induce less EMI noise, the Dual Field coil should be a little bit quiet. On the other hand, we have more copper and more turns count, which could screw the SNR. This is a great question, whether the SNR gets screwed or not. I have to make a SNR normalized coil comparision to figure it out.

I'm not a betting man, but at a guess I would say that it is the same as a normal mono of mean diameter 0.75.

One would assume this but the answer is no! Mean diameter of 0.75 won't work equal.

I see, I have a great new job to find all the interesting answers ...


Cheers,
Aziz

[Aziz]

H2O+H20=H2O????

I prefer H20 + C2H5-OH, called beer.... *LOL*

[mikebg]

Believe me or not , Aziz , but the "world best coil technology" is just the simple monocoil with additional balance circuit ...

Deemon, how should be controlled the balance circuit - automatic or manually?
How the balance circuit with MONOCOIL will suppress the GND signal?

[WM6]

How the balance circuit with MONOCOIL will suppress the GND signal?

Very easy with 8 shape mono coil, you even do not need electronic support.

[Aziz]

...
Notice, the coil comparision between the Dual Field and the mono coil was a direct coil comparison and the SNR wasn't taken into account on the Dual Field coil (just normalized to 300 µH). As we know, small coils with small coil flux area do induce less EMI noise, the Dual Field coil should be a little bit quiet. On the other hand, we have more copper and more turns count, which could screw the SNR. This is a great question, whether the SNR gets screwed or not. I have to make a SNR normalized coil comparision to figure it out.
..

Ok, the answer to the above is: only 1% less EMI noise induction improvement.
Ignore this little improvement (not significant). It has the same EMI noise induction performance compared to a mono coil.

All the additional copper wire is screwing up our SNR. Can we expect the same result with spiral coils? Or gets the SNR even worse? A lot of interesting questions and my brain is smoking...

Aziz

[Aziz]

Flat Spiral Coil Online Calculators

Interesting online inductance calculators for you:

http://deepfriedneon.com/tesla_f_calcspiral.html
http://www.circuits.dk/calculator_fl...l_inductor.htm

I need 35 loop turns for ~300 µH (Di=127 mm, N=35, w=1 mm, s=0.814 mm, -> Do=254 mm = 10"). My coil software is proposing N=34.7 for a 10 turn spiral approximation (just to speed it up, seems to work ok ).

Aziz

[Tepco]

This flat spiral stuff is interesting. I tried many different flat spiral configurations before, similar to what you going to simulate, very interesting coil configuration ( i even posted some design here time ago). I never made any computer sim. on it but just based on experience, something similar to your model, roughly 300uH, 30 turns, 2/1 OD/ID ratio works perfectly good, made of two wire speaker cable. Main reason for this physical configuration is increased inter winding distance between turns, filled with insulation, reduced total self capacitance and faster sampling. However, more interesting ways to use similar coils are obvious.


Similar to bifilar center tapped , 2wire flat spiral is also combination of two, physically and electrically identical, tightly coupled coils, but electrically insulated. Very interesting designs can be developed (i tried ) using this configuration. Say, center tapped bipolar pulsing (some issues here with shielded coil), or multi period pulsing, using constant current drive and two different voltage power supplies, or floating TX from RX part, or differential for noise reduction, or... whatever.


Practically, this type of coil performed better than standard, dual field or any other configuration so far, tested with standard detectors, or some weired configurations custom built to utilize it. Biffilar coil can be similar, enabling lot of testing and experimentation to be done. Interesting.

[deemon]

Deemon, how should be controlled the balance circuit - automatic or manually?
How the balance circuit with MONOCOIL will suppress the GND signal?

If we use the coil in a classic VLF detector ( with X-R discrimination ) - we can use manual balance , why not ? It can be stable enough , especially when we need to balance only one parameter ( inductance ) - for example , like I did in my "Faraday bridge" circuit , described here - http://www.geotech1.com/forums/showt...3-mono-coil-IB . Or if we don't want to tune it manually - it can be done electronically , during the turn-on procedure , it's not a difficult task .

But here is even more interesting idea - full automatic balance during operation time . Of course , it needs more complicated electronics , but I found very interesting solution , and now finishing the circuit based on it . Of course , there are some problems ... but I hope to solve them all successfully .

P.S. And what about GND signal suppression - I believe that this task must be solved only by electronics , utilizing the different behaviour of magnetization ( and demagnetization ) of magnetic minerals and metal targets . Why I think so - because all methods of ground balance using coil construction depends on such parameters as a distance between the coil and the ground , or maybe tilt of the coil ( with some 8-type coils ) , ground gradient , and other disturbing factors .... so I don't suppose these methods to be reliable enough . And it's also true when we speaking about RF interference cancellation ...

[Aziz]

...
Practically, this type of coil performed better than standard, dual field or any other configuration so far, tested with standard detectors, or some weired configurations custom built to utilize it.
..

You're dead right according to my first coil simulation! But I have to check the SNR yet.
(Hey, the result was an incredible surprise to me, that I've began to check my coil software and coil model .. But there isn't any mistake.)

Aziz

[Orbit]

excellent Demonn!!!