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 simple circuit is from a Radio Electronics from July 1965. The circuit can be assembled with...
Found in the May 1975 issue of Radio Electronics magazine, this circuit turns on after a certain...
We found this circuit in a 1965 General Electric documentation. The circuit generates synchronized...