This circuit was found in the September 1984 issue of Radio Electronics magazine. The frequency is given by the capacitors. The diodes help in the starting process.
Found in an 80's Elektor, this circuit can control loads up to 750 mA with the BD139 and 100 mA...
This circuit was found in a General Electric documentation from 1970. It is used in an optical...
This circuit emits a sound at regular intervals to prevent you from falling asleep, for example. It...