[sdiy] I'm new here and have a problem with a VCO

[tomg@efm]

You need a current source...in this case a dual pnp exponential converter
is what you want to use.

Connect the emitters together to a 10K resistor to +V
Connect the collector of the input transistor to gnd.
Connect the collector of the source (2nd) transistor to the 10K going to pin1
Connect the base of the source (2nd) transistor to gnd
Connect the base on the input transitor to a 1K to gnd
Connect the base on the input transitor to a 47K resistor to the wiper of a
50K pot then +V on a terminal and -V on the other this is your frequency pot.
Connect the base on the input transitor to a 22K resistor to a 50K trimmer
this is your scale trim.  Your 1v/oct source would connect here.

Tom


my name is Christian Döhn. I live in Germany. In electronics I am a newby.
My actual project is the Penfold synthesizer. The VCO doesn't work. Here is
the schematic:

http://www.armory.com/~rstevew/Public/SoundSynth/00_PenfoldSynth/Fig06.jpg

What voltage and current do I need on pin 1 to hear something?