This bidirectional circuit was found in an American documentation from the 80's. The LEDs are common red, and the resistor is calculated according to the formulas next to the diagram.
This circuit was found in a 90s EDN. Its purpose is to increase the efficiency of operational...
This LED indicator circuit uses an LM339 comparator. The circuit was found in the January 1995...
This circuit was found in an 80's General Electric documentation. The circuit uses uncommon...