Found in Radio Electronics from the 90s, this circuit is intended for analog TV applications of the time. The transistor used as well as the module are uncommon components today.
The sound produced by this circuit, from a 1978 publication, depends on the humidity between the...
In a September 1992 Radio Electronics article, we found this basic 555 circuit used to generate fixed...
This circuit is suggested by Motorola, using a 4N26 type coupler and an MC1733 type operational....