[sdiy] Three-Phase VCO

[Tim Parkhurst]

Hello All,

First off, Happy Christmas!! Hope you all got exactly what you wanted (which
would mean that the world's supply of MiniMoogs, 2600s, Fairlights, PPGs,
and CEM chips has now been exhausted... and Keith Emerson's Monster Moog has
been cloned fifty-seven times).

Second off, this list has made my year. It's interesting, entertaining,
maddening and enlightening all at the same time. Sort of like a really good
video game ;) My thanks to the whole community. You guys and gals ROCK!

Third off, has anybody fiddled with this circuit yet?

http://www.edn.com/article/CA149120.html?spacedesc=designideas

It's basically a voltage-controlled (actually current controlled)
three-phase sine oscillator with a 1,000 to 1 range.

It's about as simple as something like this is going to get; three U04
inverters (other inverter types won't work), three caps, six diodes and a
few resistors. The schematic also shows a PNP transistor used as a VC
current source. Looks like it could use an expo converter instead on the
control side. One part I don't understand is the 5V source between Vdd and
the inverter chain. How exactly would this be wired up? Still, it looks
interesting. A cheap, three-phase VCLFO could certainly be fun to play with
(great for sweeping those three stage Solina-style BBD chorus units we're
all building... don't tell Harry). What would this sound like as an audio
osc? 

Anyway, have a groovy (day after) Christmas and a Happy New Year! Please
don't forget to take a taxi home if you're out drinking. We want EVERYBODY
to be back on SDIY in 2005!

Cheers!

Tim (Designated DIYer) Servo


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