Found in a 73 magazine for radio amateurs of the 1980s, this circuit uses a dual-gate MOSFET. This component is not currently common.
This circuit uses common diodes as sensors, triggering when the temperature rises by touch,...
Simple timers can be designed using inverters or any other gate that can be connected as inverter. Figure...
This circuit was found in the 1987 Radio Electronics magazine. The components used are integrated...