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.
We found this circuit in a publication for radio amateurs in 1977. The circuit allows the...
This circuit was found in an American documentation from the 90's. The circuit can use almost any...
This circuit was found in an Electronics World of 1968, making use of components of the time, not...