So I’m currently putting all the components for breadboarding the MFOS WSG into an order with Rapid Electronics here in the UK. I’m not sure about a couple of thing though.
On the website, there are mods for adding Channel A & B Zany Frequency Indicator LEDs. There’s no mention of what kind of LED to use though and I don’t have enough knowledge to work it out. What sort of forward voltage should the LEDs have for the 9V powered WSG…? Or does it not really matter, as it’s all controlled by the value of the resistor that’s in series?
I was thinking of buying some of the Kosmo Minis to help with mounting pots and jacks. The link to the 2x12 pin headers leads to a discontinued product. Maybe I’m just being blind, but there doesn’t appear to be anything similar on the Rapid website. Does anyone have a link to some…?
Turns out my old digital multimeter hasn’t survived being kept in a metal box in my shed for a couple of decades. Can anyone recommend a budget beginner model?
The resistor controls the current through the LED, and the 1k resistors used there will limit the current to a range that pretty much any standard LED can handle (roughly (9−2)/1k = 7 mA for a typical red LED, a bit lower for other colors).
Weirdness is a Kosmo format synth module based on the MFOS Weird Sound Generator.
For this module I incorporated the WSG’s two voices (each two audio oscillators (Weird and Wacky) and a low frequency oscillator (Zany)) but omitted the filter (Oddness). 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 +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.
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 two chips, four transistors, 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.)
