Found in a 90s Popular Electronics, this touch switch uses a single sensor. PLLs are common today. Observe the supply voltage range.
12 V battery chargers provide higher unregulated voltage. With the regulator shown, obtained from...
This circuit consists of an inverter powered by only 4.5 V. The circuit is from a 1967 Mullard...
This circuit was found in an American documentation from 1969. The circuit memorizes when a...