We found this circuit in the February 1983 issue of Radio Electronics magazine. The 4-digit circuit is based on dedicated integrated circuits of the time. The power supply is not shown.
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...