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 is from a publication from the 50's. Inductive components are critical, and...
This simple two-transistor circuit used transistors from the 60s, having been found in a...
This circuit uses an oscillator that generates a signal of approximately 1450 kHz to test...