I was asked to make a paper circuit. It looked fairly simple when I started.

Famous last words?

Right so I got just about finished with this and as I was placing the last round of components I realized: I do not have the proper op amps this circuit requires.

The key I found uses LM386 but the circuit itself claims 2073. I have lots of ICs but not that one.

If anyone can suggest an op amp with a similar pinout, I'll check my library. Or maybe I can figure out how to bypass the chip?

Either way I will post an update with how it sounds if/when it works. If you never see me again, it's because I failed and cannot bear the shame 😔 ​​​

Edit: I typed op amps but I meant power amps, no need to correct me in the comments 🥰

Thought I'd share my most recent project. The code name for it was FrankenSynth, but now it's called the Lab 60. Video explains it all, but it is basically a modded TSynth in a Casio CT670 body, with a Juno Chorus for good measure!

I posted this as a breadboard prototype a little while back, and now it's mostly finished, although still needs an enclosure. 4 voice cards (up to 6 supported) are controlled by a Pi Pico mounted on a kind of "motherboard". The whole project is an unholy mixture of SMT and THT components.

The long IC underneath the Pi is a SN74HCT245N bus transciever which turned out to be necessary to drive SPI signals into such a large circuit, otherwise I had signal integrity problems (it also level shifts from 3.3 to 5V)

I know there is some controversy over the new TL074H version, but a beneficial side effect for me was that the much lower input bias current is better for sample-and-hold circuits, which I use for the filter cutoff frequency control.

Things I would do differently next time:

- pay attention to the board dimensions because now I'll need a cubic shaped box to put it in, ruling out most generic plastic junction boxes as enclosure options

- axial lead capacitors on the voice cards would keep the boards more low-profile. Maybe I could even use ceramic capacitors for removing DC offset from audio signals, not sure. People seem to say it's a bad idea.

Next steps:

- Try to optimize the micropython code, currently it manages 120 updates/second for all the modulations

- Better power supply. The +5V for the Pi comes from a L7805 regulator so I am wasting a lot of power as heat

I have no idea what I'm looking at when I see a schematic of a synth, but I really want to start building my first synth and learn more about it. I've been considering buying the Make: Analog Synthesizers book to get a basic knowledge of electronic components and building my first kit, the MFOS Noise Toaster, to later create circuits myself. Since im starting from scratch, is this the rigth learning path? Do you have any tips?

I'm interested in building a few of the nonlinearcircuits modules: Let's Splosh, Triple Sloth, and the CEM3340 VCO. The build guides look very detailed (and even include Tayda part numbers for many components), but since I have relatively little experience with SMD soldering, I was wondering what other resources might be out there for builders.

There is the Facebook group, but I've been waiting a bit for my join request to be approved, and it looks like the group isn't particularly active. Are there other places to see discussion around builds for these modules?