This circuit is from a 1977 Radio Shack manual. The photocell is an LDR and the operational one is a 741. Components with non-standard values can be approximated.
We found this 3-digit digital odometer for bicycles (or another application) in a 1995...
This circuit was published in a 1977 English magazine, but remains current, since we can assemble it...
In the figure we have the configuration of series regulator protector suggested by Motorola in 1968...