Like bipolar transistors
are also manufactured as light-sensitive devices, the action of impinging light replacing the function of triggering voltage.
Optically-controlled SCRs are often known by the acronym LASCR
, or L
. Its symbol, not surprisingly, looks like Figure below
Light activated SCR
Optically-controlled TRIACs don’t receive the honor of having their own acronym, but instead are humbly known as opto-TRIACs. Their schematic symbol is shown in Figure below
Optothyristors (a general term for either the LASCR or the opto-TRIAC) are commonly found inside sealed “optoisolator” modules.