#synth diy

[synths-and-sensibility]

Baby girl is coming together!

[taperwolf]

So here's another modular synth accessory that I probably spent too much time building, but I'm happy having it: a tunable keyboard. Each button, when pressed, outputs a voltage in proportion to its potentiometer. It's basically an analog sequencer without the sequencing. (If you've seen the ∅-Control, it's that basic idea.)

The circuit is straightforward, and taken mostly from this one in Handmade Electronic Music; the parts where I can claim originality are just in choosing the case — one of those five-compartment bead storage boxes from the craft store — and in the power supply. For obvious reasons, you want a steady and consistent voltage feeding into your buttons and pots, so I didn't trust straight USB power, and I further decided that the knobs should cover about two volts/two octaves. So I kludged up a circuit around the venerable LM317 voltage regulator to take the nominal 5V from a USB supply and yield a constant 2.7V (ish): two octaves, after the diodes' voltage drop.

(The knob positions in the photo, if your VCO is tuned so 0V is a C, are at the next D E F G and A. You can plink out "Doe a Deer" through the line about "Fa".)

Anyway, it's kind of a silly device if you think of it as purely a note generator, but I'm expecting to get more use from the circuit's stated purpose from the book: quickly selecting CV presets, to control something like a voltage-controlled radio, or of course the Radio Music. I also expect it to work well for jumping settings around on things like Clouds.

(Once day comes around, I need to try running the thing into both the sample and clock lines of a sample & hold; I've meant to see if that'd work for something like a ribbon controller for a long time, and this may approximate that circuit enough to learn something.)

The initial build worked except for the middle button; I ended up having to replace that pot, as there was a strange disconnect in it that didn't show up under ohmmeter probing.

(Also I probably should have gone to bed when I finished instead of taking all this time for a post.)

[rubbish-audio]

Moog 3p modular, Synclavier II, Yamaha CS 80, Minimoog, Korg MS-20 and various other instruments at the Deutsches museum

[technician-the]

It's bandcamp Friday!

 Most of my music is downloadable for free, but I still think today is a good day to check it out!

[deliandiver]

Friday night build

[praxidyke]

if you look closely, you can see the exact point where my wire management plan shit the bed

[mysynthfetish]

R-8 backlight DIY

I picked this up off the Yahoo Flea Market app. It's seen better days but works fine. I had a Mk II aaaaaaaaaaages ago. I forgot how goddam huge these things are. I was killing time on YouTube and saw someone doing Autechre style stuff with an R-8 and was like OH YEAH! That was right around when I had one and I was doing similar stuff, though I was shit at putting actual tracks together. Oh well. Anyway so yeah tharr she blows! As I mentioned, I had the Mk II version and that one has a backlit screen, which the first version does not have, so I thought hmmmm inverters are probably super small to drive that tiny of an EL sheet, and a step-up power converter probably won't be too big, and I can probably find an el-cheapo made in china deal for peanuts on Jamazon or AliExpress, so let's do this! I got the step up converter from Jamazon. I think I had to buy a set of 8 and it was like ten bucks. I tapped the legs of the 7805 +5V regulator for the power source and ground. Set the pot on the step up thing to output +12V, ran that out to the inverter for the EL sheet, cut the sheet to size, wired it all up, plugged it in, turned it on and hoped for the best. Worked fine first time.

Went with "red" for no real reason. If I get sick of it I'll just buy a blue or blue-green sheet. They're like ten bucks for a sheet. The inverter was about fifteen bucks? I got those from Kyohritsu, a major electronics parts supplier in Osaka. I always use them or Akidzuki. In this case it was Kyohritsu because they make the backlight screen kits themselves, and I've always used them for EL sheets. Here's what the business end looked like when done.

I used double-sided tape to secure the step-up converter there on the right, but because of me forgetting to trim the legs off the inverter components (not done at the factory, tsk tsk) I used a set of clippers but that didn't work 100% so I hot glued the inverter pcb there on the left. LOTS of free space on that PCB in the R-8. I had to cut a small hole in the metal noise shielding sheet that goes between the main PCBs and the keypad/drumpad PCBs to feed the EL sheet power wires through, but yeah no big deal. I also checked the voltage on the battery while I was in there. It's still fine. Something that surprised me was that there is NO whine at all with this inverter. Super easy job. Yay!

[swankyangles]

This thing is a mess, works though, but needed a buffer on the clock output, also a hard learned lesson on the difference between scientific and musical division. Hence the inverter module.

The panel, layout and circuit are all borderline experimental for me. Acid etched looks p neat, but not enough contrast for my liking.