PCB coil for PI detector

[mustafayilmaz]

Hi all,


I know it is difficult to make handmade coils with copper wire.


I am thinking of making a two layer pcb coil, I think the capacitive effect will be too much.


Coil dimensions will be 250x250mm and ~ 350uH. Serial and parallel connection between 1st and 2nd coils is possible.


I plan to increase the current capacity by coating solder.


Coil 1 will operate as tx and coil 2 will operate as a fully isolated Rx coil.


What do you think about that?

[Carl-NC]

I think winding coils with copper wire would be much easier and cheaper. If you make a PCB coil then heavy copper (2-oz or 3-oz) will help.

[mustafayilmaz]

Thank you Carl.

[bernte_one]

tesoro use pcb coil for sand shark, as i remind

i made also a pcb coil, not expensive if you do at by yourself.

[bklein]

How about the PCB coil in multilayer form but also cut notches in it for a basket weave RX coil?

[gabryx]

It is certainly much easier to do it with PCB, but the thickness of copper is less than a wire, so with the wire you can make more turns than with PCB, with a lower Ohm increase.
I am attaching here an image of the first construction test I made of 135 mm.
What you see in white is the double-sided tape, but when I do the final one, I saw that it is better to cover the entire surface with the double-sided tape.
Also in this test I hadn't pulled the copper wire well (which comes from a washing machine motor) so there are gaps between the coils.
The wooden cross helps in the creation of the spiral.When the spiral is finished, the wooden cross is removed and sprinkled with epoxy or polyester resin.
The magnetic field that develops with the spiral is halfway between the edge and the center, so it is better if the spiral starts from the center, even if the first turns are really short.

[bbsailor]

It is certainly much easier to do it with PCB, but the thickness of copper is less than a wire, so with the wire you can make more turns than with PCB, with a lower Ohm increase.
I am attaching here an image of the first construction test I made of 135 mm.
What you see in white is the double-sided tape, but when I do the final one, I saw that it is better to cover the entire surface with the double-sided tape.
Also in this test I hadn't pulled the copper wire well (which comes from a washing machine motor) so there are gaps between the coils.
The wooden cross helps in the creation of the spiral.When the spiral is finished, the wooden cross is removed and sprinkled with epoxy or polyester resin.
The magnetic field that develops with the spiral is halfway between the edge and the center, so it is better if the spiral starts from the center, even if the first turns are really short.
[ATTACH]57799[/ATTACH]

gabryx,

Coil shape will affect three major coil characteristics.

1. Coil inductance with bundle wound coils having the most inductance for the less amount of turns. Spiral coils will need more turns to get the same inductance as a bundle wound coil.

2. Coil resistance. This is based on the coil wire gauge used and the coil construction technique listed above as either a spiral or bundle wound to obtain the desired resistance.

3. Coil self resonance frequency. This is based on how much capacitance is seen between the coil wire turns due to insulation materiel dielectric and insulation thickness which holds the conductive wires farther apart.

Then, when you need to add a shield to the coil, the spiral wound coil and bundle wound coil styles will each impose a different amount of coil to shield capacitance that affects the coil self resonance frequency.

The important variable to define when making a coil and selecting a coil shape is the time constant of the smallest target you are seeking.

Joseph J. Rogowski

[gabryx]

Okay, but I was talking about how the magnetic field develops in a spiral coil compared to the classic round one, that is, it is more like a pinpointer in the spiral one.
In your opinion, how should a shield be made with respect to the photo I posted?
Or should a shielded wire be used at the start? .... but in this case we have a smaller number of turns in the same diameter.