How is a phototransistor represented in TPC schematics?

In TPC schematics, a phototransistor is represented by a standard transistor symbol that includes light rays emanating towards it. This representation effectively indicates that the transistor can be triggered by light, which is a key function of a phototransistor. The standard transistor symbol consists of three terminals, corresponding to the collector, emitter, and base, just like any typical bipolar junction transistor. The addition of light rays serves to inform the viewer that this particular transistor is sensitive to light, distinguishing it from ordinary transistors that are controlled by electrical signals alone. This visual cue is crucial for anyone reading the schematic, as it conveys the unique operational mode of the phototransistor within the circuit.