This circuit is for 12 V batteries but can be used with batteries of other voltages by changing the zener diode. The trigger point is adjusted by R1. The operating system accepts equivalents.
This circuit with JFET was obtained in a book on FETs of 1989. The circuit is still current since...
This circuit was obtained from National Semiconductor documentation from the 1990s. The circuit has a...
Found in 90s documentation from Analog Devices, this circuit employs operational amplifiers of the time....