If you are new to DIY electronics, this is the second module you should build. The first module, the
is ideal for beginners, as it teaches how to solder, and familiarizes the builder with the
concepts of signal and ground, the basis of electronics. If you successfully built the multiple, this
mixer kit will familiarize you with the other components you’ll be seeing: resistors, capacitors, ICs,
and power.
The
is an active signal mixer. This mixer can operate on +/ 12 or +/ 15 volts with no
adjustments. This mixer is a DC mixer, meaning it can be used to combine audio and/or cv signals.
This mixer could be used to feed multiple oscillators into a filter, or to feed multiple cv sources into,
for instance, the cv in of a filter.
The circuit itself is quite simple, and uses two Operational amplifiers in a unity gain inverting
configuration. The P14 pots attenuate the input signal then feed it through 100k resistors for
protection into the first opamp, which mixes the signal. The 5th pot controls feedback into the
opamp, in order to control master output of the mixed signal. The output is then inverted. The
second opamp is a simple inverter, that then provides a noninverted output. In audio mixing, an
inverted signal is essentially irrelevant, but for CV, you typically want a noninverted signal.
Otherwise, your envelope will be inverted.
