PE Minisonic Oscillator

Sam Doug · Joined: Nov 05, 2012 Posts: 6 Location: Truro, England

Im attempting my first DIY synth. For the oscillator circuits Ive decided to to use the PE Minisonic from 'Practical Electronics' magazine:

http://www.timstinchcombe.co.uk/forums.html?pge=pemini

For the VCF and VCA I am going to use Thomas Henrys designs from 'An Analogue Synthesizer For The 21st Century'.

I am having trouble getting the correct voltage and current readings from the control node in the oscillator from the Minisonic. There should be a 0.95V reading coming from the output of the op-amp IC1 with the pot VR2 set at 0. The current output from TR1 should be in a logarithmic scale as the pot VR2 is turned to -6V max. Im not getting any of these readings and wondered if anyone can help me?

Sam

StephenGiles · Joined: Apr 17, 2006 Posts: 467 Location: England

I would be more inclined to build a VCO designed by Thomas. I attempted to build the minisonic back then and I never got it to work very well.

Sam Doug · Joined: Nov 05, 2012 Posts: 6 Location: Truro, England

Yea, Ive been thinking the same thing. I have been looking at the VCO-1, and think i should give it a go. Thanks for the advice.

magman · Joined: Feb 04, 2009 Posts: 351 Location: Liverpool, UK

If I remember correctly, the original Minisonic oscillator was a 0.5V per octave design, rather than the industry standard 1V per octave. Something to watch out for if you want to use it with more standard circuits as you have already stated.

I hope this doesn't discourage you too much though, as there are loads of designs out there to choose from

Regards

Magman