Triacs are bidirectional ac switches that can control loads with currents as high as 25A rms at voltages as high as 600V. They find wide use in motor-speed, heater, and incandescent-lamp controls.

One of the biggest challenges for new, energy-efficient CFL and LED-based lights that will replace incandescents is working with existing triac-based dimmer switches. Triac dimmers vary widely in both ...