Theremin circuit with CV out

[sean k]

http://photobucket.com/albums/y115/quickkiwi/?action=view&current=thereminCV.jpg
 Its from a magazine and the rest of it is a CV to midi converter with game port,midi and serial port outputs but the above is the basic hand capacitance to control voltage out.Though it might be an idea to mod it for the regular CV output to control oldy analog synths using ...what was it..oct per volt?

[Paul Perry (Frostwave)]

The main problem for driving an analog synth from a theremin CV out, is that you need a gate control as well to turn the synth on & off.
Which I do with mine, just having a comparator coming on when the CV out is just above zero. But that means every note starts from a low pitch.

And for the gate voltage, of course there are many different voltages wanted.. the two main systems are 0 for off & +10V for on, but Moog & Korg expect the other way around (strictly speaking, they expect a jack to be shorted for ON, but the +10 off & 0 ON seems to work OK).

At least it doesnt matter whjether the synth is tuned or not, just adjust where your hand is :wink:

[ExpAnonColin]

A bit of confusement:  What sort of transformer is that? ..and why does it say, "as above"? Does at the bottom just show how you should wire the antenna to the board?

-Colin

[sean k]

those transformers are the regular little radio cans with the different colured slugs.They are tuned to 455kHz and the bit where it say"as above" simply means that the exact circuit that is above is below except for different antennae and opposite halves of the LM358.

[ExpAnonColin]

I got it now. Cool circuit.

-Colin