This modified novelty light bulb runs on 4 AA batteries and when combined with a potentiometer and a momentary switch for light triggering can come in handy if you are playing at a dark venue and wish to use your optical theremin. I would also suggest that something similar can be used to “tune” your theremin to the ambient light around you if placed near the light sensor and adjusted carefully with the potentiometer. I always resorted to using my cell phone’s back lit screen but that doesn’t work so well especially if your phone is programmed to turn off the light after 30 seconds of inactivity, kills the solo for sho.
Video of the Optical Theremin Light in action.