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 circuit that triggers an SCR was found in volume 5 of the 1995 Encyclopedia of Electronic Circuits....
This 1-transistor oscillator circuit was found in the March 1965 Radio Electronics magazine. The...
Found in a 1964 CQ magazine this circuit consists of an automatic telegraphic key, providing the...