May 2025: Smooth sine waves, open hardware and disappointing trilogies
Eurorack VCO
This has been a very long project which is finally starting to come together. Last year I came across Moritz Kleins youtube series on building your own analog synthesizer. At the time I was struggling to get to grips with some op-amp circuits in one of the older products at work, so I figured working my way through the series would be a fun way to get back into analog design.
Unfortunately things have dragged since I first bought all the parts. I spent a long time trying to find either a cheap pre-built power supply or a design I can build on the cheap. Neither of them have manifested themselves so I'm still planning to power the boards with batteries, which is obviously not ideal. I also decided I wanted to start with the VCO (Voltage-Controlled Oscillator) which is arguably one of the more complicated designs Klein has covered. Since its the bit that actually produces the sound though it's probably the most sensible place to start.
After all of that, the schematic is finally done. The original design puts out a voltage-controlled sawtooth and square wave. I also found some simple circuits to convert the sawtooth output firstly into a triangle wave, then that into a sine wave. Since these will require more parts than what I originally ordered I'll probably solder those circuits at a later date.
I'll write up a longer post going into more detail once I've finished but I'm currently getting ready to work on the PCB. Hopefully once I've figured out where to place the power connector on the board, I can order the board by next month and find out all the things I missed in the design 🙃.
Open Hardware Summit 2025
I've been away for a lot of this month so while I haven't got as much project work done as usual, I did make it to Edinburgh for this year's edition of the Open Hardware Summit. I attended it last year for the first time in Montreal and had a great time, so I was excited when they announced a UK venue for this year.
I'm planning to write a longer post about this but a few highlights:
- The sewable badge using conductive thread
- A lot of interesting talks - the Mothbox project, the Quetzal-1 CubeSat, the bioreactor protein production and the factory test systems were my personal favourites
- The wearable techniques panel
- The Open Wave-Receiver workshop, particularly when we managed to tune into a Scottish football station using a radio mainly comprised of a rock and two tent pegs
Seen & Read
It's been a disappointing month for reading. I slogged my way through two follow-ups to much better books. Mona Lisa Overdrive, the final book in the Neuromancer trilogy[[1]] continued the trend from Count Zero by having multiple POV characters rather than just one. I found a couple of them interesting but as with the second book, I'd rather read a story with one compelling character than several okay ones.
[[1]]: It's actually the Sprawl trilogy but I've yet to meet anyone who's even aware that Neuromancer had a sequel, let alone a whole trilogy.
Authority, the sequel to the brilliant Annihilation, ended up being a bit weird. Most of the book seems to focus on the difficulties of middle management, rather than Area X itself. One scene towards the end did help save the book quite a bit for me however, so I wouldn't completely write it off as terrible[[2]].
[[2]]: SPOILERS: Specifically the previous director returning to the Southern Reach facility. Great scene.
Finally, a few interesting links I've seen: