We found this circuit with the LM3914 IC in a Radio Electronics magazine from June 1985. The circuit is intended for monitoring the battery voltage through an LED bar.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...