TRIAC, from Triode for Alternating Current, is a generalized trade name for an electronic component that can conduct current in either direction when it is triggered (turned on), and is formally called a bidirectional tripod thyristor or bilateral tripod thyristor. TRIACs belong to the thyristor family and are closely related to Silicon-controlled rectifiers (SCR). However, unlike SCRs, which are unidirectional devices (i.e. can conduct current only in one direction), TRIACs are bidirectional and so current can flow through them in either direction. Eg. BTA series. Quadracs are a special type of thyristor which combines a "diac" and a "triac" in a single package. The diac is the triggering device for the triac. Quadracs are used in lighting control, speed control, and temperature modulation control applications

pulled away from the switch, the reed switch will go back to its original position. An example of a reed switch's application is to detect the opening of a door, when used as a proximity switch for a burglar alarm. The reed switch contains a pair (or more) of magnetizable, flexible, metal reeds whose end portions are separated by a small gap when the switch is open. The reeds are hermetically sealed in opposite ends of a tubular glass envelope. Available in 2 pin & 3 pin. Available in various sizes up to 52mm length.