This circuit is from Radio Electronics from March 1977. The integrated circuit is from that time and the circuit is intended for an infrared audio link. The modulation is in pulse frequency.
The given number circuit is used to activate the relay by interrupting the light beam that hits...
In the figure we have a simple and efficient way to obtain rectangular signals from an astounding 555...
This circuit, for 78xx series integrated devices, is suggested by Motorola in its 1990 Linear...