Litz Wire Coil

[green]

Double sided tape. I just made it yesterday in about 10minutes

Looks nice, have you tested for inductance and SRF yet. I tried a flat spiral with awg#28 magnet wire. Don't remember if I tried with double sided tape. I have to try again, might be a lot easier than the flat basket I've been making with a form wrapping around tooth picks.

[6666]

there are a number of methods to wind a flat spiral , I use a round former for the middle and spray glue for the wire to stick to backing board , then hand wind, sticky glue holds the wire
you can stack the windings as well. I've only used pvc covered multi strand wire so far, like in post #30.

[ionut_mtb]

In the midle of my picture in post #30 is a plate. With double sided tape is very easy to make it, on a peace of cardboard. The wire is telephone wire, probably same found in cat4,5 cable. I don't know exactly how thick it is, probably 24awg and probably pvc insulation. Coil have ID 18.5cm, OD 24.5cm, 317uh 333uh with rg58coax, 2.5ohm, 477ohm dumping resistor. tested on my surf pi, it goes as in the picture without shield under 10us (aprox8us). I only do air tests inside my room, coil unshielded so maybe in real world is totaly different. I find it sensible to small gold cross i keep for testing, than the normal monocoil.
I want to make a really fast coil, but i'm stuck in buying the silver plated teflon insulation wire. Little expensive. Does anyone have a good source in europe? Cheapest found on ebay is 21 US $ for 24meters, plus shipping...

[dbanner]

Always wanted to try this idea: Using double sided sticky paper as backing, wind two strands at the same time in spiral, then peel away one strand leaving space between windings( one strand acts as temporary spacer), then coat with epoxy. This would surely reduce interwire capacitance?

[6666]

Always wanted to try this idea: Using double sided sticky paper as backing, wind two strands at the same time in spiral, then peel away one strand leaving space between windings( one strand acts as temporary spacer), then coat with epoxy. This would surely reduce interwire capacitance?

Its a vicious circle, your idea works to decrease interwire capacitance but the resistance and number of windings increases.

[Altra]

Its a vicious circle, your idea works to decrease interwire capacitance but the resistance and number of windings increases.

Hi 6666
Is it worth winding coils this way? Any improvements?

Thx

[dbanner]

I take it the teflon acts as spacing also? Then winding two strands of enamel wire, then removing one strand might provide similar spacing? Sure, you may have to wind a few turns more, but the increased resistance would be small. Just something i might try to experiment with.

[6666]

Hi 6666
Is it worth winding coils this way? Any improvements?

Thx

If you compare a round random bunch wind coil to a flat spiral you should notice a increase in sensitivity to small objects , small coins etc also if your machine is good at detecting gold IE gold nuggets there should be a increase in sensitivity to small nuggets, ESPECIALLY if you stack the windings IE 15x15 rather than 30 turns.
They are actually quite easy to make and a number of different ways with former or none, keep the resistance low, adjust number of top stack for the required inductance.

[dbanner]

Air1, Teflon2, epoxy resin3.6

[dbanner]

If you compare a round random bunch wind coil to a flat spiral you should notice a increase in sensitivity to small objects , small coins etc also if your machine is good at detecting gold IE gold nuggets there should be a increase in sensitivity to small nuggets, ESPECIALLY if you stack the windings IE 15x15 rather than 30 turns.
They are actually quite easy to make and a number of different ways with former or none, keep the resistance low, adjust number of top stack for the required inductance.
[ATTACH]41110[/ATTACH]

[ATTACH]41111[/ATTACH]

[ATTACH]41112[/ATTACH]

I'll have a go at this and see what results i get. Looks good.

[6666]

I take it the teflon acts as spacing also? Then winding two strands of enamel wire, then removing one strand might provide similar spacing? Sure, you may have to wind a few turns more, but the increased resistance would be small. Just something i might try to experiment with.

Yes give it a try, you may find two strands of enamel wire difficult to wind because its springy, you may find alternative materials easier to wind, just experiment and dont get too hung up on what it looks like. What you are making is a commercial product.

[6666]

I'll have a go at this and see what results i get. Looks good.

with a can of spray glue its very easy, i use a 3mm mdf back board, and a cardboard disk in the centre same height as the windings, wind bottom layer spray windings then wind top layer it helps if you wind with the "set" or "curl" in the wire.
if you go against the "set' then it goes down hill fast. I put the spool of wire on a broom handle and the wire comes off easy with the "set" I wind by rotating the back board very important !!!!

[James]

Wow just read the results to my question on winding spiral coils. I am amazed at the response to my inquiry. I am also very interested in the results of the test you folks are , preforming . Thanks again an the folks on this board are the best. Best to all Jim

[ionut_mtb]

Air1, Teflon2, epoxy resin3.6

Depend what resin you use! Check specs, and see dielectric strenght for each resin kw/mm.

[ionut_mtb]

If you compare a round random bunch wind coil to a flat spiral you should notice a increase in sensitivity to small objects , small coins etc also if your machine is good at detecting gold IE gold nuggets there should be a increase in sensitivity to small nuggets, ESPECIALLY if you stack the windings IE 15x15 rather than 30 turns.
They are actually quite easy to make and a number of different ways with former or none, keep the resistance low, adjust number of top stack for the required inductance.
[ATTACH]41110[/ATTACH]

[ATTACH]41111[/ATTACH]

[ATTACH]41112[/ATTACH]

6666 i've learned that coils have to be winded clockwise. I see u do the opposite. Did i learned wrong???