Moog 1954 coil question

I was lucky enough to find coils suitable enough for making the 1954 Moog theremin. My question is, is it really necessary to "shave off" some of the windings for the one coil, instead of making them identical? I had a very hard time finding these coils, and don't have any spares if I screw it up, so could I just make them identically shaped? Has anybody built this particular theremin and did this? Does anybody have any input\insight?

Thanks

Looking at the article + schematic, I dont think you will manage to get satisfactory operation if both pitch and volume coils are identical.. If there was a simple way, I think it likely that Bob would have worked this out!

To me, there would be little point in going to the trouble of procuring coils for this theremin, and then ignoring the explicit instructions that these are "the heart" of the machine - if you do that, you might as well have wound coils based on the instructions, but using easily obtained materials.

I think that the pitch coil is the more important one - so having an original, unmodified one of these is the most important.. The volume coil could be constructed in some other form if you messed up the modification.. Leaving both coils identical is likely to cause interaction between pitch and volume oscillators, which really screws theremins!

I figured this was to be the case. I was hoping that there was some "trick" i could use to get around it or something. I am not an electronics genius but I was aware the coils were the heart. I was just hoping to not mod the one, as I am very accident prone...

Matt

Just post a link to the schematics please. There is perhaps a way to vary some capacitors in order to use the unmodified coils in both circuits...

Hi Thierry,
Link to this is the first in the TW schematics page..

http://www.thereminworld.com/moog1954.asp

One could change the value of the capacitor across the coil, therebye changing the frequency.. BUT.. I think the change in capacitance would give a different sensitivity than the original.. If a simple change like this did not have adverse effects, I am SURE Bob would not have gone to the trouble of having different windings on each coil.

What I would probably do is this.. Measure the inductance + resistance of the original coil, calculate (roughly) what the specified changes would do to the inductance of that winding, then proceed - I could then check that the modified coil was close to the expected, and also have the essential data on hand, in case I needed to re-wind a coil because I had bodged it!

Thanks for posting the link for me, I've been busy. I didn't figure it was easy to make a modification. I believe Moog made it the best with what he had, I just thought I'd ask anyway, never know. Thanks for the advice everybody.