This circuit controls the intensity of a light (incandescent bulb only, 200W max, not included) in response to the level of the audio input.

The circuit uses an optical coupler (MOC3021) to provide complete electrical isolation between the input audio signal (low voltage circuit) and the light's AC supply voltage. The kit operates from the AC line voltage. This kit should not be built by or for children! There is an additional risk in that the heatsink is connected to the AC supply - so it must not be deployed where the heatsink can be touched.