Right, While I've not been updating this thing I have actually advanced the project quite a bit, to the point that it's not worth me trying to fill in the gap in any kind of detailed way. The following is a brief summary of what's happened since the schmitt triggers:
I made an ADSR generator, didn't work. Then I thought maybe it was because I had to have a VCA to connected the ADSR and the oscillator into. Did this, still didn't work. Scrapped the ADSR, focused onthe oscillator. Built a triangle generator, decided to then build a sine oscillator and realised how much harder a nice roundy wave is to make! looked at lots of different sine wave generation techniques, read this!
Looked around for schematics, tried to build Thomas Henry's VCO-1 but it wouldn't work. Copied just the triangle to sine section of his design and used it with this triangle generator to nice effect; then realised that the resulting circuit wasn't voltage controllable. Couldn't get Thomas Henry's version working for some reason, in fact any circuit I tried that used OTAs (Operational Transconductance Amplifiers, they produce a current instead of a voltage and have a 'bias input' which affects the current at the output) wouldn't work! Set about looking for a voltage controlled triangle wave generator circuit that just used standard op amps and found this bad boy. Built it, hooked it up to the breadboard triangle to sine converter and felt very pleased with myself.
I've also built a 4 step sequencer, also on breadboard and based on the 'Baby 10' sequencer.
Now I have to build an exponential converter for the VCO and put the whole thing on a PCB, so I'm working on the schematic and looking at PCB etching techniques. More details on this present situation in the next post.
Phew! Glad that's over, Now I can actually start updating this regularly with the stuff I want to talk about!
-JW
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