This two-digit circuit was found in the 1999 Radio Experimenter Handbook. It uses the CA3161 and CA3162 A/D converter pair common at the time.
This circuit is from 1968 documentation. We can assemble it with more modern components such as a...
Found in a 90s Silicon Chip documentation this circuit is intended to protect a speaker system in...
The UVTRON tube is an ultraviolet radiation sensor. In this circuit from Radio Electronics from...