Found in a 303 Circuits from the 90's this circuit can use the lowest current range of a common multimeter. The circuit can measure currents as low as 100 pA.
When the sensor X1 is opened, the relay is energized. When waiting, the current drained is very...
This circuit can also use other series operational amplifiers such as MC33172, MC33174, MC35171,...
This circuit was originally designed to power the CB18698's MSX interface, but it is suitable for...