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.
The figure shows how to implement an R-S flip-flop or bistable reset-Set with an LM3900...
This circuit was found in the SGS manual of linear integrated circuits of 1982. The CMRR depends on...
This simple circuit with transistors turns on a small lamp when it gets dark. The sensor is an LDR...