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[Milo Barrowclough]

hello everybody
 
I love electronic sound and i am well into all kinds of synthesizers. Recently i have been trying to build my own rudimentary synth. I have made a simple 555 oscillator that works great. Since the then i have been trying more advanced circuits involving op-amps, but without success. I have tried to make r.a. penfold's vco, penfold's filter, and a basic lm3900 VCO. Whenever i try any of these circuits , it either emits nothing or a quiet buzzing noise. I am almost certain that my circuit is correctly built, i've checked the bastard about 50 times. Can anyone help me? I think that the problem may be the power supply, i am using an old scalextric (model car racing) transformer that puts out 12 volts. Is this a common problem with op-amps? Whats going on? 
Thanks very much
Milo


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