[sdiy] 566 , was Re: Midwest Analog Product Books

[WeAreAs1 at aol.com]

In a message dated 9/27/04 7:46:38 AM, jmahoney at gate.net writes:

<< The quadrature outputs made me think "Great for an LFO!"

Unfortunately, though, the triangle wave doesn't hold together at

frequencies below 80 Hertz. I'm not sure how low the square waves can

go, although TH's books shows 10Hz with a -6V input. If it'll go even

lower then it may be useful as an LFO. >>

Hello John,

What if you were to simply use a much larger main timing capacitor?  I'm 
thinking something like about 10 times the size of the cap in Tom's original 
design.  That would effectively move the whole range of the VCO down into useful 
LFO range, extending your very slow LFO times to allow much longer LFO sweeps, 
move the "sweet" range of LFO operation closer to the middle of your CV range, 
and hopefully, clean up the triangle shape in the most useful part of the LFO 
frequencies (about 0.5Hz to about 40Hz, IMO). This might relegate that 
expected triangle waveform distortion to the very lowest, and less useful, parts of 
the LFO's frequency range.  I'm just guessing that this might help a bit.

Michael Bacich

P.S. -- BTW, I haven't seen his circuit, but if the accuracy of the 
quadrature outputs is somewhat frequency-dependent, then you might also have to 
accordingly adjust some cap and resistor values in that part of the circuit as well, 
if you want to range everything down into LFO territory.