SCR Printable Version https://www.controlbooth.com/wiki/SCR This page has been seen 2,516 times. Created by derekleffew on Aug 12, 2013 Silicon Controlled Rectifier. The most common type of phase control dimmer. The SCR, a thyristor, is used to switch the AC waveform to vary the amount of power to a load. Always used in pairs, an SCR resembles a spark plug.