I built my first computer in 1976 using an 8080 and an evolution of operating systems starting with a a home-grown system similar to the Digital Equipment Corporation ODT (octal debugging tool). I added cassette tapes and moved to a Sol-20 "cuter" tape system and a DIY 40 column printer. Then I added 8" DSDD floppy disks and the CPM operating system. I added the General Instruments AY-3-8910 programmable sound generator IC to the system for my audio effects. Here is a photo of my 8080 system before the upgrade to floppy disks and CPM.
I was sent a personal PCB for the SN Voice. I never did experiment with the SN76477 Complex Sound Generator so was interested in building this module. I used cut tape 2N3904s for my expo converter and epoxied them together with a 2K tempco resistor.
This is my 3U MOTM-style panel design for this fully featured module. The panel is a FrontPanelExpress with legend printing instead of engraving which was about a 50% cost savings. The white legends are more a light gray than bright white in color. The mixer switches are 1P3T to select high, low, or the input jacks. I implemented the Birth Of A Synth gated mode modifications for the envelope switch. I used NKK for the flatted handle to match my other modules.
DJB SN Noise Deluxe FrontPanelExpress design (printed graphics)
The top controls have limited clearance to the edge so I used 12 mm potentiometers as well as a small (and expensive) Grayhill 3 position switch (Mouser 706-56A36-01-1-03S) for the LFO range. The switch has a 1/8" shaft so it requires the (expensive) 1/8" shaft knob (Mouser 506-PKES60B1/8). I bussed ground and +5V and wired input jacks directly to their attenuator potentiometers to minimize panel wiring.