Found in na 1969 Electronics World, this circuit makes use of transistors of the time. Equivalent transistors can be used. The diodes can be 1N4004.
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...