This bargraph circuit is from an ancient American documentation. It indicates the charge state of a set of 4 batteries from 9.6 to 5.2 V.
The range of generated signals depends on coil L1. The circuit was found in old English...
This circuit was suggested by Electronic Engineering in a 1980s publication. The circuit makes use...
This automotive tachometer circuit uses a FET and a 1 mA full-scale instrument. We found it in the...