John used a LM566 VCO in his 5700 Drum Synth. He extended it's range but did not use a exp conv. As it is it's not useful as a 1v/oct VCO but it could be if someone adds a exp conv. 566 VCO Pin 1 -V Pin 2 NC Pin 3 Sq Out Pin 4 Tri Out Pin 5 3.3M to +V and 1M to gnd Pin 6 CV in Pin 7 .05 to -V Pin 8 +V -Tom