Saffari: first listen and oscillator details

Yesterday the PCBs arrived for the prototype of my analog transistor organ monosynth and I built it.

It sounded great so I made a little video of my first jam and posted it to Mastodon, where it got some really nice comments.

In theory the oscillator generates a square wave, but because it’s made using a super simple circuit and discrete components (just like the transistor organs of yore) the square” is actually more like a chunky asymmetrical blob with rounded corners”. That’s why I love analog synth circuits and that’s why I love the sound of this little creature.

In case you’re interested, here’s the oscillator circuit:

Saffari oscillator circuit diagram

The KEYBOARD input connects through a big old resistor ladder with switches to the 9V rail, so the keys basically vary the voltage at that central point, which in turn varies the frequency of the oscillation. The resistor ladder idea comes from the Pif synth and the oscillator circuit is from Transistor Electronic Organs for the Amateur, a coffee table classic:

“Transistor Electronic Organs for the Amateur” book cover

transistor organ oscillator circuit diagram

That diagram contains a hint as to how I added the all-important vibrato, but I’ll write that up another time…

January 12, 2023