This simple TTL circuit indicates which was the first to press one of the four pressure switches. The circuit must be powered with a voltage of 5 V.
This circuit was found in an Electronics World magazine from 1990. The circuit can be mounted...
This interesting circuit was found in a 2006 publication. It is a timer that controls the engine...
Using a 709 integrated circuit this circuit was found in the June 1972 issue of Radio Electronics...