This is based on the stepped tone generator by Forest Mims also know as an Atari Punk Console, but with a few added bells and whistles. You have controls for frequency and pulse length, but also a volume control and low-pass filter. External light sources tweak the sound with a selectable photo-sensitive sensor.
It is housed in a white aluminum die-cast case with reused knobs that have some cosmetic wear. It is powered by an external 9-volt battery with toggle on/off switch and LED power indicator . Output is via a standard 1/4″ output.