i've been toying with this idea for a while now.
the thing i hate about phasers is that they whoosh up and down predicatably, boringly, and annoyingly. would it be possible to replace the oscillator that controls this with an expression pedal? i have some experience building/understanding pedals, but just don't know enough EE to know if this is possible.
i mean, isn't this ultimately just a very specific delay pedal with a very narrow, pedal controlled range of delay time?
Yes, it is possible. In fact, many phasers come with this control already in the form of a trimpot on board to set the initial notch range. Remove the trimpot and run those pads out to a footpedal and you can have yourself a foot-controlled phaser.
Another interesting thing you could do to remove the "uninterestingness" of predictable swooshing is to build the S/H part of the Maestro Sample/Hold circuit and use this output to drive the phasor instead of the LFO. All you need to do is find the LFO output, disconnect it, then replace it with the S/H output and you have a random phasor.
... or the random control voltage generator at GEO...