The Photo-theremin is a bit different than a traditional theremin in that it is controlled by light. This particular Photo-theremin is different than most because it uses 2 photo-transistors instead of a photocell. Because it uses light it actually responds differently with different types of light. For example, with a traditional light bulb it produces a square wave sound like a more harsh traditional theremin, and under a flourescent light the sound is more noisy and thin. It also responds different to effects lights, such as strobes. What you get is a unique sound and more playability because you can vary the types light into two different photo-transistors for amazing results! The range of the Photo-theremin is also much greater than any I have heard it ranges from extreme lows to highs that actually extend above the audible range!
This Photo-theremin also has a built-in effects/feedback loop. This allows you to run effects into the theremin and alter between affected and unaffected sounds. I refer to it as a feedback loop, because it does more than a traditional effects loop. Even with the Theremin off, your pedals running through the loop will feedback into themselves and produce sounds just like a feedback loop would! This makes for some nice noise and makes your effects impact the Theremin sound more intensely.
Another component of this Photo-theremin is the LFO, or Low Frequency Oscillator. The built-in LFO has a huge range and can range from subtle siren effects to all out noise generation! There is a speed knob, and bright blue LED that flashes with the LFO rate.
The controls for the Photo-theremin are: volume/blend knob, LFO rate knob, 4 mod/effect switches, master on/off switch, and LFO on/off switch. There is a 1/4 inch master out and a 1/4 in and out for the effects/feedback loop. On top are the 2 photo-transistors and bright blue LED that flashes with the LFO speed. This instrument is powered by one 9V battery.