This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are general-purpose types. The circuit triggers when the light that falls on the sensor is cut off.
This circuit is from an 80's component manual. The components are from the time, but the circuit...
This circuit was found in a 1994 documentation. Speed measurement pulses are obtained by a reed...
This circuit was found in a 1980s document. The integrated circuit is from the time and the power...