Found in the October 1979 Radio Electronics magazine, the purpose of this circuit is to monitor the coolant level in a car's radiator. The circuit is based on the LM1830.
This commercial NEC radio circuit from Japan has an audio power of 300mW and uses 7 germanium...
This sophisticated timer has several activation modes and operation monitoring through sequential LEDs....
This simple circuit from a 1987 documentation can be used in robotics and automation, as well as...