Found in Ferranti's 1968 documentation, this circuit uses a Darlington photo transistor to drive a 12V relay. The circuit can be implemented with modern equivalent components.
This circuit was found in a 1967 General Electric documentation. The circuit generates signals...
Sine signals are converted into square signals by this simple circuit. The maximum frequency is...
We found this touch control on a Popular Electronics from 1970. The circuit makes use of an...