Googling for a random LFO brought me to the Ken Stone schematic which I have used as a jumping off point for my own design. I have chosen to run my own CD40106 inverter IC from +15v to VDD instead of -15v to VSS as suggested in this schematic. I've also opted to use a TL071 op amp.
CD40106 Data Sheet with all the specs. This IC will be used to generate a pseudo random square wave oscillation via a feedback loop.
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An example of the expected wave shapes that will be produced by the output of this module. Both smooth and square wave output will add a nice complement to the functionality of this module.
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LFO - Module
This is an LFO design based on a feedback principle. I use an inverter IC to create a random modulation. I'm building some custom vactrols out of photo cells, LED's, resistors and shrink wrap. I will use these to modulate the resistance value within the feedback loop thus generating a true random waveform which will be used to modulated other devices within the modular synthesizer.
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