Litz Wire Coil

[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.

[dbanner]

Air1, Teflon2, epoxy resin3.6

[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]

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.

[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

[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.

[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?

[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...

[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.

[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.

[ionut_mtb]

I have a question, about construction of a spiral coil, using Litz wire. I for the life of me can not understand how to wind the coil without it falling apart. There must be some form of a special device used in winding the coil, because the Litz is so flimsy. Thank you all for any advice you can share with me. Best to all Jim

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

[James]

I have a question, about construction of a spiral coil, using Litz wire. I for the life of me can not understand how to wind the coil without it falling apart. There must be some form of a special device used in winding the coil, because the Litz is so flimsy. Thank you all for any advice you can share with me. Best to all Jim

[James]

Thank you for sharing the information about the spiral wound coil. I now curious about building a coil, when I get a few extra minutes. I am going to measure the capacitance of my home made coils. I think I will have a better hands on feeling for making faster coils. Again I would like to thank the members of the board for sharing the information. Best to all Jim

[dbanner]

As you can observe, at least from this comparison, the fastest coil is the flat radial.

[dbanner]

All thing being equal, generally speaking, it seems so. take a look at these coils which were measured.