[sdiy] A hacked phasor, with vactrols

[Aaron Lanterman]

Christine and Xavier put a lot of work into breadboarding and tweaking 
this:

users.ece.gatech.edu/~lanterma/ece4803/drafts/phasorschem.jpg

It's based off an existing phasor schematic (what's shown here is just a 
draft for SDIY eyes only - the final version will have the original 
sources attributed). They ripped out the LFO circuit and rigged a 0-5 CV 
input to the center frequency. They also replaced the mix pot with two 
vactrols. They put in a switch to give the user the option of using a knob 
or using a control voltage to control the mix. The CV input on the mix 
doesn't seem to give the same dramatic change as the pot does, but you do 
hear a change as the CV mix input is swept.

To keep things simple, I suggested they keep the original ground-9V power 
scheme, instead of trying to switch everything to -15/+15 V. What's the 
most _elegant_ way for them to get 9V from the +15 V in the MOTM? Of 
course, there's three dozen ways to do it...

They're about to start committing to solder... any last minute advice?

(Since this isn't going into a stompbox pedal, I suggested they go ahead 
and use the 5532...)

Actually - Christine, Xavier, when you build, socket the op amps - that 
way we can drop different op amps in, like the 4558 suggested by Harry, 
and listed to the difference.

- Aaron