This circuit for cars with fans was found in Silicon Chips documentation from the 90s. It is used to activate the fan when the radiator water temperature rises.
This beat frequency oscillator or BFO was found in an American 1980s documentation. The circuit is...
We found this setting in the Texas Instruments opto-electronics manual. The bipolar can be the...
This bistable control uses a 4069 as bistable. The circuit can drive relays up to 100 mA with the...