This circuit was found in a 1970s documentation. The components are from that time, and semiconductors are difficult to obtain today.
This circuit was found in a 1965 Electronic Design. The transistors are of the time, but the...
Found in a 90s Popular Electronics, this sensor operates by infrared reflection. The components are...
The time of this timer depends on C1. The circuit was found in the July 1994 Electronics Now...