The Benjolin is a relatively simple but wonderfully clever analog, complex sound generator designed by synth pioneer Rob Hordijk.
Here’s what Rob has to say about it on his website.
“The Benjolin is a ‘noise box’ that is ‘bent by design’, meaning that it always has a definite amount of unpredictability while it is still intuitive to play. The Benjolin features two eighteen-octave range voltage controlled oscillators that drive a ‘rungler’ circuit, circuitry that in essence uses a special interference technique feeding back into the oscillators to force them into wild chaotic behaviour.
A special slightly chaotic filter is both excited and modulated by the signals from the rungler circuitry processes, producing sounds between fat drones to grungy noise havoc.”
Here’s all the info that Rob has put online about building your own Benjolin:
*PCB parts layout*
Here’s a slightly modified version of the schematic I put together.
The original version (linked above) is spread over 4 pages. I’ve consolidated it to one page and made a few changes to the labeling in order to make it easier for myself to read.
I’ve been working with the Benjolin a whole lot over the past year or so. See the links at the top of the page for some of the pieces I’ve built around this awesome circuit. I’ve listed a few modifications and additions worth checking out if you are considering building your own.
The mods can be found here.