AETHERPHON, global theremin family

> The tone oscillators are around 190 KHz, the volume circuit is running
> in the neighborhood of 400 KHz. I haven't checked recently. I almost
> threw this thing in the lake Saturday. The oscillators were literally
> driving me crazy. They would stop working if you touched the antennas
> or even looked at it crooked.

Ok, you may see second-harmonic energy from the tone osc getting into
the volume osc..  That could cause some interesting effects.  On the
schematics I've seen, the tone osc is normally the higher one.
Would it be really hard to move the volume circuit to say 300kHz?
I'm thinking to put them in places where they don't have any direct
integer harmonic relationships.

Decoupling the power supplies is really important too, and star-grounding.
I'd use R-C decoupling in series with each oscillator's supply, and
try hard not to share bias voltage supplies, or anything else.
Basically, make the oscillators three independent (or four if that's
the design) modules that have only B+, Ground, and output connections.

> Sunday afternoon I found a Navy technical text on the internet that
> dealt with this sort of thing with Hartley style oscillator
> instabilities and I just changed a couple of biasing resistor values,
> and VOILA, the thing WANTS to work now. I was VERY concerned that if I
> made (make) major modifications to the circuitry of Mark's design to
> make it work it will not sound right.

It's possible, the oscillator waveshapes do come through in the mixing product.


> I don't have a LOT of experience about how a theremin is supposed to
> sound but Kevin your statement means a LOT to me. All this frustration
> and hard labor has not been for naught.

:)