Single layer Spiral coil

[Davor]

I wouldn't play with any core because of the added weight. There were some designs employing ferrite rods, but not a complete horseshoe.
You may think of a humbucker as a cross-section of a torus. Because air gap is very large here, don't expect to gain any benefits from any kind of core and feel free to abandon the core idea altogether.
A picture? usually such configuration is referred to as OO and it depicts it well enough. If in one "O" current flows in clockwise direction, in the other it flows in opposite, and they are connected in series. That's it.

[Tinkerer]

Is it possible to use a thin alu-plate as some kind of reflector?

If yes, how much distance should it have to the coil?

You can use a Bucking coil at a small distance above the TX coil, as seen on my Avatar.
The current in the bucking coil is in opposite direction to the current in the TX coil.

This produces some degree of deflection, as you can measure. To measure, try to detect a target at the same distance above the coil and below the coil. You will not a significant difference in target response.

Tinkerer

[Funfinder]

You can use a Bucking coil at a small distance above the TX coil, as seen on my Avatar.
The current in the bucking coil is in opposite direction to the current in the TX coil.

This produces some degree of deflection, as you can measure. To measure, try to detect a target at the same distance above the coil and below the coil. You will not a significant difference in target response.

Tinkerer

Is it possible to disign the bucking coil as flat spiral also?
Or perhaps shaped like a basecap without sunshield.

some other thoughts also could be of interest:

- cylindrical coils (like for wireless power transmission) are
directional so they may also improve detection depth

- spiral coils can be created with 3 to 10 thicker ring areas
like usual coils for creating real powerful inductivity

- the design of the spiral coil could have the shape of an
upside down mushroom, UFO or cone to create an intense
field area for smaller stuff closer to ground

[Jeroi]

I made this now as you Davor suggested. It has outer diameter of 20cm and the inner coil diamemter will be about 8cm.

www.youtube.com/watch?v=RsWQ6vytNwk

What do you think of this?

I think of addin 2 coils in series. The inner coil has opposite direction as outer one. Would they produce quite nice magnetic field?

[Davor]

I made this now as you Davor suggested.

Nope. I suggested coils of the same size side by side, one next to the other. This solution in video is as per Tinkerer's solution.
Go for it, Aziz also speaks fondly about this configuration.

[Tinkerer]

TINKERERS_TANDEM COIL

Nope. I suggested coils of the same size side by side, one next to the other. This solution in video is as per Tinkerer's solution.
Go for it, Aziz also speaks fondly about this configuration.

There are many useful coil configurations possible.
The choice depends on the goal.
The most used coil configurations are for most used detector uses.

If you have a specific purpose, you can build a specific coil that is best suited for that purpose.

Below is a field visualization of a TANDEM COIL, where the coil windings are in series and the fields aiding.

Tinkerer

[Tinkerer]

Spiral Bucking coil

Here you see a spiral coil with the graphite shield and a spiral Bucking coil on top.

Tinkerer

[Davor]

Ah! So the tandem is a proper name. Thanks. Anyway, you can see a (somewhat squashed) toroid organisation of magnetic field in there. Exactly what I was talking about.

You have nice visualisations, including the one in your avatar. I am seeking some software without learning curves, and I hope you can recommend some. It is often straining job to picture all these configurations in my head.

[Tinkerer]

For a visualization of coil fields, compare the 2 pictures below.

With the current in the 2 coils running in the same direction, the fields are aiding.

With the current in the 2 coils running in opposed direction, the opposing fields repel.

A RX coil positioned in the position where the magnetic fields are rarefied, will sense only a weak TX. This is what we use to reduce the Flyback peak, in the RX. We call it a Bucking coil.

Tinkerer

[Davor]

I really like your visualisations very much, and I still wonder what software produces them :wink:

[Tinkerer]

Ah! So the tandem is a proper name. Thanks. Anyway, you can see a (somewhat squashed) toroid organisation of magnetic field in there. Exactly what I was talking about.

You have nice visualisations, including the one in your avatar. I am seeking some software without learning curves, and I hope you can recommend some. It is often straining job to picture all these configurations in my head.

Here you can download free applets for all sort of visualizations. Excellent site.
http://www.falstad.com/vector3dm/

Enjoy

Tinkerer

[Tinkerer]

I really like your visualisations very much, and I still wonder what software produces them :wink:

The Avatar is from a magnetic field visualization made by MIT. I think they use MAXWELL, BY ANSOFT. Ansoft used to distribute a free 2D magnetic field software Maxwell 2D. I think it is excellent but I have not had the time to really break through the learning curve.

Tinkerer

[Davor]

Here you can download free applets for all sort of visualizations. Excellent site.
http://www.falstad.com/vector3dm/

Enjoy

Tinkerer

That's more like it! That's exactly a tool I was thinking about: no learning curve at all

Thank you very, very much!

[Aziz]

I really like your visualisations very much, and I still wonder what software produces them :wink:

Hi Davor,

you are still after a "sexy" coil software.

If you have a specific coil idea in mind, you can suggest it for a coil analysis.

The only condition is, that it must be discussed and published in the public domain. If it has some merit, it shouldn't be patented either (Patent trolls!, go to the hell please! Thank you. ) . We the (honest and peaceful) folks share our ideas and inventions together. Sharing is a good thing and it kills the evil greed.

Do you have something to share with us?
It would be a pleasure to me, to help you and others.

Cheers,
Aziz

[Davor]

you are still after a "sexy" coil software.

Just found it, thanks Tinkerer. The script works like a dream. It would be a tad better if I could enter my own coil designs.

I'll have your kind offer in mind when I manage to design something that is not already in use /patented /misunderstood etc.

This tandem coil thing with counter phases (a torus stand-in) works exactly as I imagined it, and I think it must work well in "monocoil" solutions.