A triac functions as two inverse-parallel silicon-controlled rectifiers sharing a single gate, allowing it to conduct current in either direction once triggered. It remains latched in the conducting state until the main current drops below a holding threshold, which naturally happens twice per cycle in an AC circuit. They are the primary switching component in domestic AC light dimmers and motor speed controls.
Heard on the job
The dimmer switch is buzzing because the triac is chopping the AC waveform too aggressively.
Also heard as
- TRIAC
Do not mix it up with
- SCR: An SCR conducts in only one direction, whereas a triac conducts in both directions.