coil resonances - Aziz

[simonbaker]

hi,
mi theory to understand difference of the responce a coil like same is the "parasitic" magnit flows created of "Unparallel
" turns of the hand made Coils, When made Hand Made coil every turns i not Perfectly Paralel to other turns in coil this made flows with Phase diffrant from the Main Pole. When i null coil may by null received signal when main pole is unbalanced because i null total received sygnal (main pole + "parasitic" pole) AAAND this point is the critic!! Parasit pole in every created coils is diffrant! may by need to put smal target with knownled response in the sensitiv area and adjust same response with good worked coils, and after that remove target and adjust null whit small single coil who is moved to adjust null received signal, After this NOW adjust responce from target and if necessary retry operation to have best response and best nulling

Ivconic you have too more experiance from me in this works, please say my your thinks about this , and if you have free time may bi try

i don`t have enout time and where try this because work under other projekt

thank before


SORRY FOR bad ENGLISH

I have often wondered about the alignment of windings because often when I wrap my coils I see wires that don't lie parallel -- just a few I think.

However, I don't see why they would have significantly different phase effects because of it. In the end, I would think all the little magnetic fields should combine with the main magnetic field and not make much difference to the target or receive coil. It could affect the nulled residual signal, but I don't see how small variations there matter either.

But because there is a mystery about coils, I'm open to all ideas. Something must be the cause that makes one coil so much better than another. My first guess would be some kind of "tuning" with the receiver circuit, but I have tried to "tune" bad coils and not found success.

-SB

[whiskey]

Coil Resonances

And here I thought the control box did that providing the wire length/diameter is correct.

Nice pic of two coils. The shielded coil looks done and might make a decent mono coil if the shape works. Not sure of how much of a performance hit the shape is going to cause.

But, why is it being paired up to the other coil. Is a DD type coil being made? If so, then why shield the one seperately? Don't both coils have to be within the same shield for a DD?

[simonbaker]

I still have a feeling that most mysteriously "bad" coils that were built basically to correct spec could be made to work well with some kind of compensation - just don't know what it is at this time.

-SB

[whiskey]

Coil, Coil, Coil and Trouble...a cauldron of problems.

This Thread is Dead!

Cheers

[WM6]

It is dangerous to drink whiskey out of beer glasses.

[simonbaker]

This Thread is Dead!

Cheers

DD coils not in same shield -- where get that idea?

Also need to investigate real value of shielding TX coil -- proof by experiments.

This thread will come back if/when actual experiments done.

Cheers,

-SB

[whiskey]

GO,GO,GO______________________________Treniers

LOL. WM6...Good advice. Had one beer today and now I'm having some scotch whiskey. It may not make my headache go away, but at least I'll feel better, LOL.

simonbaker quotes:

DD coils not in same shield -- where get that idea? ~ Production search coil assembly. TX and RX within same shield.

Also need to investigate real value of shielding TX coil -- proof by experiments. ~ Shielding providing too much capacitance? I dunno. Is investigation now removing shielding in question? Choice of shielding type and quality may be of value. Maybe, I still dunno.

This thread will come back if/when actual experiments done. ~ Someone better get busy. In the mean time I'll stick with backwards engineering.

Now that I think about the coils pictured, they remind me somewhat of the BigFoot design for Jimmy Sierra's product line. I can't say about the shielding, but the design may be of interest. Slim them up a bit, maybe? Sounds like another test. Good thing wire is cheap. Best not to use cheap wire.
We'll I be, my headache is gone.

[Mikes]

Hello, all!
There are certain criteria which need to be observed at work with any coils. The most important thing is experience and practice. Try to make coils and to finish them to excellent parametres (waste time). I think, that questions will disappear.
Here small continuation:

[whiskey]

I Sure Hope My Search Coil Looks As Good As His.

Mikes, you are so right about certain criteria needing to be observed. Depending on which detector that is being designed for it is best to follow close to original coil design specifications. Then reverse engineer improvements into it.

For the most part properly finishing them to those excellant parameters, which may be a waste of time for someone, may be what is needed to make a better coil.

I don't think the questions will disappear. To properly design an improved coil someone might ask, "At what frequency/resonance and current/resistance do I test for inductance?" Not sure what makes or breaks a coil design but the questions will never disappear.

Whatever detector the new coil is being designed for I suggest finding an old coil and tearing it apart. Be very careful so as not to cause too much damage. Look at how it is shielded. Or what is not shielded. See how the wiring is routed and what size/type of wire is being used. Also find what wire the shielding is connected to. Another good idea is to observe anything that may not look correct, like corrosion, brittle wire or flaking shielding.

What is nice about making a new coil it can be tested before enclosing it. Make any size or design change and hook it up and see what it will do. Grant it, it is not under actual conditions but it is a start. If it doesn't work properly it can be debugged or redesigned. Make another and test...test...test.

After all that, we only have an uncertified cheapo LCR. And to think, for the price of a decent LCR, I can buy a new search coil. LOL, yeah team!

Such is life, Nice coil Mikes.
whiskey

[Ultimate_Haze]

Hi,
Mikes.
Can you tell me for which metal detector is that coil?
Also interested how you null the coil?

good work

[Mikes]

Hi,
Mikes.
Can you tell me for which metal detector is that coil?
Also interested how you null the coil?

good work

Greetings, friends!
Diameter of the coil about 8 inches.
Criteria: 1). Pressure of a food (8 volt – TX about 50 turns, 12 volt – TX about 80 turns, 18 volt – nearby 90 – 100 turns), RX in 1,2 - 2 more turns and more thin wire).
2). Frequency the above, the is less than turns TX.
This gauge for Fisher 1266. The template is taken from article – http://mikes.front.ru/str2_3_e.html
Held preliminary testing – result 0,3 mv on RX (peak value). Dime USA – "catches" in 14 inches (in air).
The zero is cancelled: 1). Distance change centre to centre coils.
2). Introduction of a compensating coil in TX the coil.
Now it is necessary to fill in a gauge part «epocsid» with pitch, then again to arrange and again to fill in.
Toothpicks are necessary for time adjustment of the coil.
MikeS

[Ultimate_Haze]

Greetings,
Mikes.
Please keep posting the pictures while nulling and sealing the coil.Its interesting.
I couldnt understand what you say.
How you null/compensate coil?
And what is this tird coil in the article used for?And how?

[Mikes]

Greetings!
Promised to show gauge fabrication stages.
Look!

[Woody.au]

If I ever need a life preserver I know who to call.

[luciano furtado]

If I ever need a life preserver I know who to call.

I wonder if anyone knows what the best stuff to make and blidagem coil below 100Khz for less effect of land of aluminum or copper??
thank you very much