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.
Found in American documentation this circuit uses transistors of the time. The circuit can be made...
The TAA300 integrated circuit is not common today. In fact, the circuit shown is from a Dutch...
This circuit was found in a 1980s documentation. Q1 and Q2 can be BC548 and SCR a TIC106. The...