This TTL circuit is from a Radio Electronics magazine from February 1973. The circuit must be powered with 5 V and the maximum frequency depends on the TTL integrated circuit.
This circuit is given in two versions, having been found in a publication from the 90s. The second...
This circuit was found in an ancient American documentation. Used integrated circuits are uncommon...
This Texas Instruments circuit uses a phototransistor to fire a TTL trigger port. Other...