This very simple amplifier was found in the Philips Databook of 1990. The circuit is suitable for headphones and other battery powered applications.
This circuit, from ancient French documentation, produces a rectangular pulse from input pulses...
This control is from the Motorola Circuit Applications for the Triac of 1971. The Triacs can be...
This circuit is from 1964 documentation but can be easily implemented based on current components....