Months and months have gone by and still no playable synth, but things are getting a lot closer. I ordered a Frankensteined rack to put it in. Found a guy on Craigslist in NH who had taken apart some lab equipment which uses the same format as Eurorack systems (meaning my system could potentially house store bought modules). I also found an online metal shop in CT that does custom cut sheet metal at a damned cheap price. I ordered some small slabs of aluminum to use as panels for the modules. They gaurantee 1/8” precision on the cuts, but the six pieces I got were dead on and fit perfectly in the rack. Showed up in just two days and cost only $3/panel (way cheaper than blanks elsewhere). These are all 5.125” x 2.5”. But you can order any size you like. I went with Aluminum 6061-T6 Bare 0.063” thick. I’ll report back when I figure out how well it works. The plan is to etch designs on them and then drill holes for the panel components.
But what will be behind the panels? Since last I checked in I’ve built “One Very Cool Animal”, a single version of MFOS’s Dual Linear/Log VCA and “A Demonic Sound Reshaper”, a simplified version of Yusynth’s ADSR envelope generator. Both of those came together nicely. I’ve been refining my etching and design techniques. I started using a suite called gEDA, which is a bit cumbersome at times, but allows me easier control over the width of lines and pads. This is pretty important for homemade PCBs. I also switched paper for the design transfer. I was using magazine paper which didn’t work very well for me. I’m now using HP Glossy Presentation Paper as recommended by various blogs and it’s promising so far. Still, my latest etch had some smudging which meant I had to do a lot of cleanup on the final board. I also had a close call with the envelope generator. A couple of nights ago after weeks of design and building I had it working perfectly on the first try. However, while experimenting with it, I accidentally hooked it up backward and it died in a puff of “magic smoke”. This was in the wee hours of the morning… I went to bed very sad. But the next day I discovered it was only a resistor that blew and I had it up and running again before my tear drenched pillow had dried. I still have a lot of work in front of me. Next up I need to wire up more of the offboard stuff (audio jacks, pots and switches) then get them built into panels so I can put them on the rack. I also need sound sources. Ironically the module that started the whole project, an Arduino based digitally controlled oscillator, is still nowhere near done. I also want to build a module to plug in audio sources (guitar, keyboard, etc) so I can use the synth as an effects rack. And eventually I’d like to build analog VCOs and a MIDI to CV converter. Any one of these pieces will take weeks of work, so it’s going to be a while.