Help with kit theremin

Posted: 6/12/2010 2:53:28 AM

Joined: 6/6/2010

Hello everyone,

I've had a theremin kit from for a long time now, and it has never worked right. I've asked the manufacturer on several occasions what the problem is and each time the solutions provided have come to no avail. I'm hoping someone here may be able to help me out. <- Here's the schematics

To tune it to get it to work, you turn each of the coils until it sounds right. Now apparently T2 affects the pitch range and T3 affects the volume plate, but somehow T3 affects pitch in exactly the same way as T2 and the volume plate controls pitch as well as the pitch aerial. T4 and VR2 appear to do nothing.

Is this indicative of a dry joint or short circuit somewhere, or is the problem elsewhere? I hope someone here can point me in the right direction.

Many thanks!
Posted: 6/13/2010 6:07:26 AM

From: Colmar, France

Joined: 12/31/2007

This effect may happen if either the frequencies of the volume and pitch oscillators are too close or if the fixed pitch oscillator around T1/Q1 is not working correctly.

I wrote some time ago a detailed diagnose/repair article for this theremin model. You may find it here:

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