This is the devilS Yell, the “all mighty phunky scratching device”
I mostly use it for tryin to scratch kool rythm thingies,
but you can use it for whatever wierd soundz you can imagine ;P

I have made several of these in the 90´s and 00´s.

You can also hear it in action in the end of the track “Dark” by Paza Rahm

Controls:
The first knob is th’ tone control, th’ next the carrier vco into the ringmodulator.
Between the knobs and the red button theres the LDR that controls the main vco ;D
The red button trigger the vca. On th’ side theres a switch whit you can choose between the “clean” and ringmodulated sound.
It works on a single 9v battery.