on/off through two distinct control pulses. This includes power-switching circuits, logic circuits, lamp drivers, counters, etc. Compared to TRIACs A TRIAC resembles an SCR in that both act as electrically controlled switches. Unlike an SCR, a TRIAC can pass current in either direction. Thus, TRIACs are particularly useful for AC applications. TRIACs have three leads: a gate lead and two conducting leads, referred to as MT1 and MT2. If no current/voltage is applied to the gate lead, the TRIAC switches off. On the other hand, if the trigger voltage is applied to the gate lead, the TRIAC switches on. TRIACs are suitable for light-dimming circuits, phase-control circuits, AC power-switching circuits, AC motor control circuits, etc. See also High-voltage direct current Gate turn-off thyristor Insulated-gate bipolar transistor Integrated gate-commutated thyristor Voltage regulator Snubber Crowbar (circuit) DIAC BJT References Further reading External links SCR at AllAboutCircuits SCR Circuit Design Solid state switches Power electronics Rectifiers General Electric inventions 1957 introductions 1957 in technology 20th-century inventions de:Thyristor#Geschichte