Some questions

[Mikko Helin]

  I built a synth with Electronotes sawtooth VCO. It goes down to
0.01 Hz (but what do I do with that low frequency?). For some
reason it doesn't start oscillating every time I turn the power
on. I used BS170 MOS-FET instead of 2N4856 (or 2N4859), maybe
that's it. I measured voltages with DMM, and integrator
output goes up to +15 V and comparator fires (goes up to
0.0 V). LM311 comparator open collector output is connected
to ground through 3.3k resistor, maybe BS170 needs a slightly
positive voltage at gate to switch? (like 0.5 V or so, have to
try). 

  Other parts of that synth were 2-pole state-variable
filter (LM13600 without offset trims to save space,
CA3240 and TL082), CA3080 based linear VCA and two AR EG's,
all on a 100x160mm (6"X4") board (have Easytrax .pcb file
if somebody's interested). That VCO has one TL081 input summer, 
CA3240 (dual CA3140) integrator and current reference
and LM311 comparator. There's no waveshapers except 
NE5532 (TL072 didn't work!) saw level converter (like ENS-76 VCO 
option 1), but it's easy to modify to get square wave format 
(just replace feedback resistor with 2.2M one, with a switch).

-Mikko