This circuit was found in the March 1995 issue of Electronics Now magazine. The circuit requires a symmetrical power supply, and the FET is a common general-purpose type.
In this 2002 circuit, we have the activation when the reservoir is empty and shutdown when full....
This circuit was found in a 2001 documentation. It is a test of zener diodes that uses a voltmeter or...
The output current is of the order of 100 mA maximum, but the transistor used can be changed for...