This circuit was found in a Popular Electronics of the 1990s. The sensor is a rotating mechanical system with a propeller-driven magnet to count pulses with a reedswitch.
ON Semiconductor MC74VHX1Gx Logic ICs The Mouser Electronics series 74 Logic ICs are available for...
This is an improved version of the previous circuit also found in the December 1990 Radio...
This circuit was found the Optoelectronics Sourcebook by Texas Instruments. Any phototransistor...