Build Project: Universal/Progressive RF Coil Winder for Theremins

Posted: 12/12/2020 2:40:52 AM

From: Northern NJ, USA

Joined: 2/17/2012

"I ended up printing a two-wall cylinder (could be a single wall) vertically for the core and then an array of spacer-washers flat.  The washers were pressed onto the core and the layer lines on both create a nice ratcheting friction.  I added little 45 degree notches to each washer to give the wire at the top of a section winding to be able to return to the base of the next section with at least a little separation from the subsequent layers."  - pitts8rh

Ah, as usual, you're way ahead of me!  Makes total sense...

"None of these coils will compete with your large air-core coils for SRF and Q, but I'm not sure that you need or even want 300+ volts on the antennas?"

High voltage!  (Done dirt cheap).

But actually, yes, it could be a huge liability come compliance time (where products go to die just as they cross the finish line).  I keep trying to think of ways to reduce the voltage and spread the spectrum, but phase detection via digital means is the rub.  Maybe don't phase lock, just stimulate a low Q (RL) tank with an octave's worth of pseudo noise and count periods or something.  What I really want is shielding to make the C field more directional and kill half the intrinsic.

Posted: 12/12/2020 9:52:47 AM
Henk Brand

From: Schiedam The Netherlands

Joined: 12/22/2014

Thanks for the video of your beautiful working coilwinder. Seeing it works give so much more information then words alone. Wish i had your skills to produce such a wonderful winder. But understanding the general principles better maybe give me the chance to make one of my own.It wouldn’t be so sophistocated but as long as it works it’s allright with me. 

Posted: 12/12/2020 10:49:01 AM

From: Minnesota USA

Joined: 11/27/2015


Consider taking a look into the Morris Coilmaster or Dave Gingery's easy-to-build version of it.  They are both extremely simple designs that can make universal/honeycomb windings just as well as the winder that I made.  The Dave Gingery book is probably out of print but you may find a copy or work from pictures of winders that others have made from it. He uses an off-center washer for the cam, which makes the throw easily adjustable.  And in place of the bevel gears he uses a friction disk with a rubber-tired wheel that is easy to make and is also infinitely variable.

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