Found in a 90s Popular Electronics, this touch switch uses a single sensor. PLLs are common today. Observe the supply voltage range.
This switching regulator circuit with less than 100 mV ripple was found in a 1980s documentation. The...
This circuit has a frequency range of 30 Hz to 100 kHz with an output signal of 1 Vrms. We found...
Using 555 integrated circuits, this alarm circuit was found in a 90s American documentation. The signal...