Found in a Popular Electronics from the 90s, it applies to the old answering machines that used tapes. It emits a warning beep on the drive.
This circuit is used to protect an amplifier from excessive power output that would cause problems for...
This circuit was found in a French magazine Toute LÉlectronique from 1978. Transistors are not...
This circuit was found in documentation from the 50's. The circuit uses transistors of the time...