Archive of the former Yahoo!Groups mailing list: MOTM

I finally finished building my 320 LFO and had a great time
experimenting with the 420! I decided to put a scope on it to
determine frequency and amplitude ranges. I verified that the shape
control has the appropriate effect on the various waveforms as shown
in the instruction guide. I did not verify 1V/oct-in or shape-in.
Also, as I do not have another "tunable" sound source, I cannot
verify sync-in. I'm wondering if these numbers look reasonable:

freq control at min: not measured, but REAL slow (a technical term)
freq control at max: 31.25 Hz

sine output (peak-to-peak)
shape=0: -4.9V to +3.75V
shape=5: +-4.9V
shape=10: -3.75V to +4.9V

tri output is +-5V
shape has no effect

saw output
shape=0: -4.9V rising ramp
shape=5: +0.2V to +5.2V fairly triangle w/slightly rounded top
shape=10: -5V to +5.2V falling ramp w/slight rise before fall

pulse output
shape=0: -4.4VDC
shape=5: +-4.3V fairly square
shape=10: +4.4VDC

Note: to determine if I could get a higher output freq, I set the
rate to 10, plugged pulse-out into FM-in and set the shape to 10
(thereby sending +4.4VDC to FM-in). The new output freq was 588Hz.

Note: I tuned the 900 so that the +- supplies are at +5.00VDC and -
5.00VDC.

Ok, so I'm a perfectionist, but I'm a bit concerned about the saw
output when the shape control is set to 10, as the waveform is not a
clean ramp. Another point: the actual center of the waveform shape
adjustment is actually just a bit right of 5. Since there are no
tunables in the PC board, I'm not sure what to look for, possibly a
resistor out of spec?

If anyone has some input, that would be great.

Cheers,
George