This circuit was found in a Popular Electronics from the 90s. The counter circuit is not common today. The circuit can be programmed for hourly intervals, according to the values of R4 and C2.
We found this circuit in an Australian publication from 1991. It is a kit of the time with input...
This time base circuit was found in the January 1988 issue of Radio Electronics magazine. The...
This circuit was found in the December 1983 issue of Radio Electronics magazine. The sensor is an...