[sdiy] single transistor VCA (was OTA VCA)

Elain Klopke functionofform at gmail.com
Thu Mar 23 15:43:39 CET 2017


Hey all....

So I breadboarded this up:
http://gaje.jp/blog/wp-content/uploads/2011/12/ms_type_vca.png

I used a 2N3904 and didn't have an op amp buffer so went without it. the CV
input was provided by the two diode, two resistor and a cap AD generator.

And no sound.

Now with the labeling of 2.5V I'm guessing that the circuit is being run
off of a 0-5V power supply and the 2.5V is acting as a virtual ground.
Since I don't have the op amp in my circuit, I just went with connecting
those 2.5V bits to ground.

I'm going to be putting together a bipolar power supply this weekend, so
I'll give it another go then.

Also, my 2N3904 could be fried. The bag of them has taken a spill a couple
times and I've had to scoop them up by hand and put them back....

Tips, tricks, and scathing criticisms welcome as always
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