This circuit from a Radio Electronics from December 1974 was used in color televisions of the time. It serves as a reference for restoration work. The circuit is of the ultrasonic type.
This circuit is from 1964 documentation but can be easily implemented based on current components....
This Power supply sources from 500 to 1,000 mA according the transformar and was found in a...
This photo-relay uses a Darlington stage to increase sensivity. Any photo-transistor can be used....