Hey trick-or-treators,
Halloween is on its way. Any favorite patches?
This is mine:

Get a cadmium-sulfide photocell (like a Radio Shack 276-1657)
and wire it to a mono 1/4 inch plug.
Plug it into the PEDAL jack. Put a candle next to the photocell.

VCO1 is tuned up really high. You might need to flip the transpose
switch up and hit the highest key to get it really up there.

VCO2 gets FM'ed by the wobbly light.
Set left VCO2 FM to 75% (to start with)
Left VCO2 FM switch is down (PEDAL)

Open the VCA with the VCA GAIN slider.
Open the filter most of the way.
Set Audio Mixer for ring mod.

Tune VCO2 close to VCO1. The ring modulator gives the beat
frequency between the steady VCO1 and the wobbly VCO2.
Retune VCO2 as needed to adjust for "candle drift".

Adjust filter so you don't hear the very high pitched VCO1 or
VCO2, you just hear the beat frequency.

It's kind of an old sci-fi movie / short wave radio sound.

Add too much tape echo if available. Nothing says "old sci-fi"
like too much tape echo.

 - -- -  Toby Paddock