http://www.cgs.synth.net/modules/cgs108_vca.html
I've built a couple of these to add CV amps to an existing project but am having trouble getting them to behave. Some things to note:
- they're running off 15V so I'm wondering if there are some resistor changes required?
- I had to substitue a couple of capacitors as I didn't have exactly the right values and they didn't appear to be that critical based on my loose understanding of this circuit: the 5pF on the board I changed for a 4.7pF and the 220n required on the input when wiring up I substituted with a 100n
With a 5V peak sine wave input I'm getting horrible distortion. My latest idea was to install a 50K trimmer instead of the 100K fixed resistor on the CV input wiring to see if I could dial in a resistance value that would work better but that's no been particularly successful.
Neil