This decorative circuit was found in the July 1994 issue of Electronics Now magazine. It makes LEDs blink in a face-shaped allegory. The frequencies are given by the capacitors in the oscillators.
In the figure we show a timer, this simple one with only one of the four gates of integrated...
This circuit is a sensor for photodiodes that can be used in optical couplers, encoders and other...
This crystal tester was found on a 90s Ham Radio. Transistors are commonly used. The circuit is for...