minimum theremin troubles...please help

so i successfully constructed one of the minimum theremin based on art harrison's schematic. however, i am running into a bit of a problem. when plugged in to an amp, the theremin is very quiet. i have to turn the amp to pretty much maximum volume for the theremin to be audible. is there some sort of pre-amp circuit that anyone knows of that i could boost the volume with?

thanks!

Following Arts circuit description the output amplitude varies from 120mV (at 1800 Hz) to 2V (at 80Hz). Even the weakest value is still enough to overdrive a normal keyboard or guitar amp.

So the conclusion would rather be that there is a fault in your circuit. You should take an oscilloscope and check the voltage levels at the output of the 2 oscillator buffer stages (Pins 6 of U1 and U2) where you should find a 5Vpp rectangle signal. From there you should go further to the mixer output (Pin 12 of U1), then behind the low pass filter (Pins 9 and 11 of U1), behind the output amplifier stage (Pins 8 and 10 of U1) where the signal should be 6 to 10 times stronger than at the input. Finally check the output divider R9/R10 where you should not encounter a considerable loss.

Sorry that I took a little more than 2 hours to answer...

no need to apologize! thanks very much for the help. i will try to see if i can't get my hands on an oscilliscope for a bit...

I bought a very cheap pocket-oscilloscope-multimeter some months ago, the UT81B by Uni-Trend from a Chinese seller on ebay. For me it was still cheaper in the time when the US Dollar - Euro conversion rate was still more interesting for Europeans.

Naturally this is not a high precision lab device but it is more than enough for first aid on audio devices and theremins. A simple waveform/amplitude/frequency check is possible on the 160x160px display and that's even enough precise for tuning a Moog Etherwave Standard.