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 came out in an American magazine that no longer exists. It's the Electronic...
This circuit originally came out in a Budget Electronics from 1981. The American magazine no...
This is the traditional audio preamp configuration with the National Semiconductor LM382. The...