This circuit was found in a 80’s American documentation. The adjustment trimpot is from 47k to 100k. The diodes are general-purpose types use and the supply voltage depends on the relay.
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...