This circuit is from General Electric from the 80s, using a relay with high current contacts (20 A). The transistor admits equivalent, and any phototransistor can be used as a sensor.
We found this chopper circuit in a 1967 publication. The transistors are of the time, and current...
This circuit was found in a 1977 Radio Handbook. The ports used are CMOS like 4001 and the...
Ohmite TGHD non Inductive High Power Resistors Available in SOT-227 enclosures, these Ohmite...