The thyristor is a four-layer, three terminal semiconductingdevice, with each layer consisting of alternately N-type or P-typematerial, for example P-N-P-N. The main terminals, labelled anodeand cathode, are across the full four layers, and the controlterminal, called the gate, is attached to p-type material near tothe cathode. (A variant called an SCS—Silicon ControlledSwitch—brings all four layers out to terminals.) The operation of athyristor can be understood in terms of a pair of tightly coupledbipolar junction transistors, arranged to cause the self-latchingaction:

RexST
(Thyristor Discrete):
TYN160C 160A 1600V TO-3
TYN130H 130A 1800V TO-247
TYN100H 100A 1800V TO-247
TYN70C 70A 1800V/1600VTO-247
TYN60H 60A 2200V TO-247
TYN25C 25A 1600V/1200V TO-220
(Triac Discrete):
BTA110 1600V/1800V
BTA91 1600V/1800V/2000V
BTA71 1600V
BTA41 1600V/1200V/800V TOP3
BTA16 1600V/1200V TO-220