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.
This circuit for currents from 500 mA to 1.5 A was found on a Ham Radio from the 90s. R4...
November 2016 - Vishay's new proximity sensors VCNL4100 for display presence and activation,...
Found in a 1965 CQ magazine, this circuit uses period components. The unijunction transistor can...