The TRIAC It is part of the family tiristores, and is closely related silicon controlled rectifiers (SCR), Its name comes from English Triode for Alternating Current . The triac is formed by two SCR connected in antiparallel, c ie, one contrary to another, but in parallel and with the gates (triggers) linked together. With this type of configuration the triac becomes a bidirectional electronic switch, that can work with the electric current in both directions Guando the trigger is fired.
What is a TRIAC
The bidirectionality Power makes the TRIAC be a very convenient switch or key for circuit AC, also allowing you to control large amounts of power with just a few milliamps of current triggering your trigger.
The application of a firing pulse to a phase angle controlled, an AC cycle allows control of the percentage of current flowing through the triac for the load ( phase control ), which is much used, eg, on speeding in low voltage induction motors, in dimmers lamps, and heating control current AC.
A very used is the TRIAC TIC226 .