How to circuit bend a Gakken SX-150 synth
1--LFO-to filter cut-off (lfo frequency modulates the filter)
2--Filter resonance oscillate (when resonance is on filter distorts and produces a pitch frequency -- simply solder two wires either side of the resister labled above and add a switch too turn the short on/off
3-- frequency to voltage output (wire a output jack to the points shown above to have a volatge output that rises with higher pitch great when used with the theremin as input!!
4-- envelope trigger wire a switch between envelope pionts A and B (shown above) so you can manually re-trigger the envelope
5-- Optical Light control (add a norps12 LDR (min resistance 50ohms max 2m) across the same two pionts as the resistive strip (and a switch to turn it off and on) brighter light increases the pitch etc produces a constant tone.
as always check short before soldering Enjoy!
6-- The filter injection point (the point were R30 and R29 meet) can be used to inject an audio signal through the filter BUT i haven't tested this too much as yet it will need some form of biasing I guess using a 1-10k pot wired as a potential divider would do the trick the signal needs to be at least 0db (2.2v Pk-Pk) i.e. line level NOT guitar.