This automotive grade circuit was found in a 1991 Electronics Hobbyist. The transistors are general purpose types. P1 sets the monitoring voltage.
This circuit with JFET and Unijunction was found in an ancient American documentation. The...
This metering bridge circuit uses one power supply only. The operational ones depend on the...
We found this configuration in the 1964 RCA transistors manual. As indicator loads in each stage,...