[sdiy] finding cv on bass station

[Milo Barrowclough]

hi all

i'm attempting to add another oscillator to my bass
station keyboard synth. i built a simple triangle core
vco based on a lm13600 (r a penfold design. it uses
linear control voltage. Suprisingly, it works. i want
to hook it up so that it will play at the same pitch
as the bass station existing oscillators. i have tried
wiring the cv input to random points on the bass
station circuit. so far found one potential cv on an
ic pin. it changes the pitch, but in strange way. for
a start, it goes backwards i.e. the higher the note on
keyboard, the lower the pitch from traingle vco. also,
the notes seem to closer together in ptich than they
should be. does this suggest that the bass station
uses logarithmic cv? do all vcos use a log/lin
convertor? if they do, then in theory they will be a
linear cv somewhere. could i use the transistor array
as used in the asm-1 vco to convert? basically in want
a cheap midi to cv convertor.
 
thank

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