TTL Counter (CB21360E)

This counter from 0 to 9999 was found in English documentation. The power source must be 5V with at least 1A.

PC resistance meter (CB20544E)
We found this circuit in English documentation for PCs from 1996. The ZN448 is a very uncommon...
FCS 8100 Clock Module (CB24495E)
This circuit is from a Fairchild digital clock module shown in the March 1977 issue of Radio...
Simple Battery Eliminator (CB23694E)
This circuit is regulated by zener and provides a voltage of 9 V. The circuit is from a Radio...