These shots show a square wave being conditioned to clock a S+H module, which will (hopefully) be a part of a solar powered synthesiser that I am making.

Looking into S+H modules, I found a great youtube video by Moritz Klein that details exactly how they work – however, he specifies that a JFET transistor would be needed rather than a BJT, as BJTs have limited (and directionally uneven) current flow between the collector and emitter. I do not have any JFETs, and don’t fancy learning about them yet – BJTs are tough enough for me at the moment. I think that the future of this solar powered synth is looking very free of any S+H module …

Another issue that I am starting to be aware of is the presence of opamps in the schematic, which do not perform as well as transistors at lower voltages – opamps will simply cut out at lower voltages, whereas transistorised circuits will die in a more interesting and dynamic manner. A redesign is needed.

A day later, I am now digging deep into the world of discrete circuits – opamps are easier to work with but it is common knowledge that, for audio purposes, well designed transistor circuits can outperform their IC counterparts. I’ve already done some research on transistor square wave oscillators (bistable multivibrators), but have just managed to successfully solder a phase shift oscillator, which outputs a sine instead – very lovely to work with sines after months (years…?) of blasting square waves out of my speakers.

Now, the real problem is designing a (relatively) clean output stage to drive a speaker, all at very very low voltages. More on that in the next post.