I need to switch to decaf :)
Anyway I gave this some more thought, and had a chance to look over the
schematics of the MOTM modules I have now.
Square is useful as a clock (although I would say a 310 is a better choice
than the 390 if you want a really stable 1U clock), but PWM isn't that
useful. Saw without sync doesn't isn't that useful either, and you can
easily get saw out of other 1U modules. Everyone seems to want sine.
So this is my revised version of a micro dual VC LFO:
~~~
>I need "utilitarian", "cheap".
OK :)
>a) 3 pots, 6 jacks:
(jacks cost less than pots, LED's draw current and make noise)
1) RATE
2) FM
3) LFO 2
6 jacks:
1) FM 2) LFO 2
3) SQ 1 4) TRI 2
5) SINE 1 6) 2 SINE
At it's core are two tri LFO's. The second LFO (the one not used as a
clock source) is deliberately very unstable. The module uses inexpensive
sine shapers (like the overdriven OTA's in the 410), no tempcos, no
exponential converters (although it might make sense to make RATE a log
pot), no "gold plated" op-amps, and no LED -- 100% low-budget.
LFO 2 and FM are reversing scaling attenuators. LFO 2 is normalled to a
positive voltage. FM could also be normalled, to a small voltage, and used
as a "fine" control.
The second LFO can be controlled in two ways by using a switched jack.
Without a plug, its input voltage is value of LFO 2 plus the voltage input
to the first LFO (which is the sum of FM and RATE), such that LFO 2 serves
as an offset, and FM and RATE serve as master controls for both LFO's.
When a plug is inserted into the LFO 2 jack, the LFO 2 knob becomes an
input attenuator. This way you can patch either output of the first LFO
into LFO 2, or control each LFO independently.
SINE 1 uses a switched jack -- unswitched, 2 SINE contains the sum of both
sines (notice its name). While the SQ 1 and TRI 2 jacks could also use a
summing feature, that might be confusing.