Found ina 1970 American documentation this fast-reading circuit uses a photodiode. Transistors support modern equivalents. The circuit can be used as a shield.
This circuit generates signals of less than 10 Hz. We found it in a Popular Electronics from the...
This circuit is from a 1987 American publication called Electronics Handbook. The circuit can be...
This well-known signal generator configuration was obtained in a Popular Electronics from the...