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.
August 2017 - The new DPS1133 power switches from Diodes Incorporated for currents up to 3.3 A...
Taiwan Semiconductor Dual N Channel MOSFET Taiwan semiconductor makes available through Mouser...
This is one of the many applications of the 555. We found it in the November 1992 Radio...