This CMOS logic-based circuit was found in the April 1974 issue of Radio Electronics magazine. The circuit is based on a period display and has hour and minute indications.
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...