This TTL heads or tails circuit was found in the July 1973 Radio Electronics magazine. The LEDs are types of the time. Note the symbolic representation of this component.
When S1 is closed, the L1 lamp turns on and the L2 lamp turns off. The circuit is powered...
This is yet another version of the light-controlled oscillator that can be found on this website. This...
The A3906 integrated circuit from Allegro MicroSystems (www.allegro.com) consists of a single-step motor...