Found in a 90s Popular Electronics, this touch switch uses a single sensor. PLLs are common today. Observe the supply voltage range.
This circuit was obtained in a technical documentation on SCRs of 1976. The circuit can be...
This circuit uses a photo-transistor to trigger a circuit sourcing a square signal for the output. The...
The critical components of this project from a 1978 publication are the transformers, which can be...