Schematics

State Variable VCF

Based on CA3080. I never got the resonance to work as I want it.

Dual State Variable VCF

Based on SSM2164. Works much better than the CA3080 SVF!

Dual State Variable VCF and 1v/oct quadrature vco

Based on SSM2164. An enhancement of the filter above. This one features stable selfoscillating and 1v/oct cv-inputs. It doesn't go very high in frequency when oscillating, but is a very useful module anyhow…

Bipolar mixer V2

A very handy thing, each input has a scaleknob with "-/0/+" so it's easy to invert the signals. Each mixersections output is normalized to the next section, so that the sections link together to form as many mixers with as many inputs as you need… One channel on each section is normalized to a fixed voltage, so it can be used to add an offset voltage.

Quad fourquadrant multiplier

Built around MLT04 multiplier IC. This module may function as ringmodulators, VCA's, VC-crossfader, VC-panner, frequencydoubler (with sine input)

Voltage controlled switch

Built around MAX4533 electronic switch IC

Sample&Hold

Built around MAX4533 electronic switch IC. Very bad drooprate, maybe some better opamp-buffer and/or capacitor should do it…

Percussion Envelope

NOT TESTED. The idea is to have two alternative decay-times to choose between with logic input.

Computer Interface

This interface connects to the centronics parallell port and outputs 8 channel gate and 4 channel 1v/oct CV with 12 bit resolution. Based on MAX536 Quad ADC and 74LS244 Octal Buffer.