Found in a 90s Popular Electronics, this sensor operates by infrared reflection. The components are modern, and the phototransistor can be of almost any type.
This constant current source for high voltage loads was obtained from a 1967 General Electric...
We present a DC-DC converter circuit that can operate with input voltages from 2.4 V to 14 V and...
The trigger signal for this circuit is an audio tone. Tones up to close to 100 kHz can be used. The...