This old indicator circuit indicates only when the fuel reaches the sensor level. The integrated circuit is not common today. The circuit was found in documentation from the 1980s.
This circuit is from a 1976 documentation. It provides a pulsating DC voltage that can be varied...
The presented circuit triggers the relay when S is pressed for an instant, keeping it in these...
This circuit is from a Radio Electronics from October 1963. The LDR and transistors are from the...