Here, have some Weirdness.
Weirdness
Weirdness is a Kosmo format synth module based on the Music From Outer Space Weird Sound Generator by Ray Wilson.
The WSG is a standalone noise box. It has two voices, each of which is an audio square wave oscillator (Weird) synced to another audio oscillator (Wacky) and modulated by a low frequency oscillator (Zany). The two Weird oscillators, and optionally the two Wacky oscillators, are mixed into a resonant low pass filter (Oddness). There are pots to control the six oscillator frequencies, the two Zany modulation amplitudes, and the cutoff and resonance of the filter.
The circuit is pretty simple. A single CD40106 is used for all six oscillators. (That means it’s susceptible to crosstalk, but in this application that can only increase the weirdness.) That and a single op amp for the filter are the only chips. There are a couple of transistors, and some passive parts. That’s it. There is no voltage control in the basic design, although Wilson did publish suggested modifications to add JFET based voltage control to the audio oscillator frequencies.
For this module I incorporated the two voices but omitted the filter. I figured we all have filters already in our synths, use them! Instead the two voices go to (separate) mixing and buffering stages and output jacks. There are also gate outputs, with indicator LEDs, derived from the Zany oscillators. Other than that the circuit is taken directly from Wilson’s design, except that it is powered with the synth’s ±12 V instead of a 9 V battery.
I tested the voltage control modification but didn’t like it. It has the side effect of changing the oscillators’ square wave outputs to narrow pulse waves, giving the sound a much different timbre. So I didn’t add voltage control.
I had an idea to maybe adapt the Oddness filter after all, as a separate module. Then it and a Weirdness module — or perhaps even two or more Weirdness modules — could be mounted in a case with a power supply to make a modular Weird (or Weirder) Sound Generator. The Weirdness modules could be connected behind the panel to the Oddness filter. To enable this, I added a pin header on the circuit board, connected to the two voice outputs. I haven’t actually designed an Oddness module yet, though, and whether I ever will or not is an open question.
There are eight potentiometers controlling this module, and they need to be easily manipulated given that there is no voltage control, so I decided to make them sliders. They’re by far the most expensive part of this build! Wilson specifies linear taper pots and I don’t know why — I think audio would be better. But I was asleep at the switch when I ordered and got linear ones. The rest is still two chips, four transistors (two added for the Zany gate outputs), and some passives, on a fabbed PCB behind a fabbed 10 cm FR4 panel.
(Yes, I did tell JLCPCB to put the order number on the back of the front panel, and, no, they didn’t. First time that’s happened to me.)
Repository: https://gitlab.com/rsholmes/wsgmodule