SDIY - How I got started building music machinesAs a teenager, I had an electric guitar. My first DIY project was a UJT oscillator that I could synchronize (poorly) to a guitar that I plugged into it. I believe that the signal was connected to the "emitter", (the connection with the arrow). It would synch to the fundamental or a strong harmonic of the string being played. It was kind of cool, except that my incredible ignorance about electronics prevented me from improving the circuit with an AGC circuit, a gate, and subsequent obvious improvements, such as an envelope generator, frequency divider, etc.
The next project was a kit, can't remember the manufacturer, but it was an attack decay unit for guitar. I still have it, tho I haven't used it in years so I don't know if it still works. The circuit was published as a project in Popular Electronics, a magazine that I often took to bed with me.
After that I took some time off of music stuff and worked on radio gear for several years. I saw the schematics for the Gnome or some other show up DIY synth show up in PE, but I wasn't interested because they looked too complex for me. I have to admit that I was and am pretty lazy, so I've always liked simple circuits.
I got back into music again when I was 20. I found a cheap organ circuit board and made a crude sequencer with TTL parts by tapping off of the organ circuit board into a mux, a counter drove the address lines of the mux to select a note. I built this on a solderless breadboard and I used it in that form for many months for creating a "bottom" to make guitar practicing more interesting. It never made it to a real etched board, in fact, I did something that caused it's power supply and most of the logic on it to self destruct. From there, it found it's way into the dumpster.
Again I took a break from music machines and concentrated for many years on computer circuits.
About 5 years ago, I bought a PAiA FatMan and built that. Then while looking at it's schematics, I realized that I could do a lot of mods to it, I built a subharmonic generator (actually several), PWM, a couple of LFOs, added a PLL frequency multiplier to it (frequencies: x1 x1.5 x2 x3 x4 x6 and x12), wave shapers to make tri from saw, a triangle subharmonic, LFOs, ADSR, LFSR noise generator, nonlinear feedback VC SVF. Other things are also in the works, a VC Sallen-Key filter made of CMOS parts, another VC Sallen-Key using FET opto isolators for the frequency control.
I bought and built a second FatMan and put that one in a portable case using small cabinet hinges for mounting. The second FatMan received a third VCO, 4069UB type (a la René Schmidt) with a triangle subharmonic, an LFO for PWM, and a divide by 3 circuit (perfect fifth generator).
My intention is to at least partially modularize at least one of my FatMan synths. I have done most of the research for this, data is included on this site, and it's waiting for implementation. I need to purchase a panel for the banana jacks and a few extra modules I'll need. For modules, I'd like to add a 4 input mixer, ADSR, LFO(2), Some kind of wave shaper (not sure what kind yet) ring modulator, VC noise generator probably as s tonal noise source.