I was moving old stuff around, when I found an ancient artefact of the times long gone: A Soviet 15W ТПП-245-127/220-50 transformer (Back from year 1979 or so. Yeah, it’s way older than me, lol). Being somewhat a fan of old soviet stuff I decided to throw up a bench power supply based on that one.
So, the whole thing has a very simple circuit. A diode rectifier, 4700uF capacitor and 3 GS6300 stepdown ICs providing 3 separate channels. I also popped some 1.8A recovery fuses, so if I screw up and make a short circuit, I’ll just have to wait a little, till it goes on again. The ICs can handle up to 3A of current, but I thought that would be a little to much for this kind of bench supply.
The final part was adding some voltmeters and ampermeters to the outputs.
I also wired the /ON tracks from the stepdowns to a screw terminal on the side to later add an attiny stuffed with a vusb firmware (arduino-lovers – go home (c)). That will me to issue reboots from within the script, that actually boots the embedded boards I work with.
The last part was the enclosure. I got some old pretty thick 5mm acrylic, that was around. I have a strange feeling it’s been around since about that soviet times as well. I took it to the local lab where, I gave it a laser cut (Thanks fly out to Vladimir for helping me out with that one). After thinking for a while I added a ‘made in USSR. year 2012’ engraving on the top cover just for lulz. I used both openscad and inkscape to do the whole thing. Openscad generated me the edges of the box, since this is better done with code, rather than manually drawing that. The rest was the inkscape’s job.
Now, I think of taking another go on it, but with a better, bigger but still soviet transformer of ТАН41 series (It looks like I have a shitload of them). I have a few things I want to improve in the circuitry.
First – add an option to generate negative voltages, use just 2 diodes instead of a bridge (There’s a neat way to cut losses on the bridge) and some other misc.
I still need to find better caps for those potentiometers and secure them tightly, and, possibly add a vent. The transformer gets pretty warm if I put so 10W load on it for a while.
If you want to build your own – you can grab my schematics on my github, adjust to your liking.
More photos here.