My third post in this blog, posted a year and a half ago, shows an image of my next prototype module – an envelope generator, VCA and mixer.
This was my first foray into analogue circuitry, and as such there are some pretty strange issues with this module, particularly when using full settings on any potentiometer. These are not bad enough to stop the unit from functioning, but I would be highly unimpressed if I purchased a mixer which seemingly swapped the phase of each half of the stereo signal above a certain output level!
An Arduino NANO was used to generate the envelopes needed, but everything else was achieved using op-amps and RC filters. The op-amps chosen were LM324 quad amps, and these were the first chips I experimented with other than the Arduino boards.
