This circuit was found in a 1969 Mullard publication. The transistor may be the modern equivalent of BC548. Observe the relatively high supply voltage.
The 3-digit AD converter on this circuit is not very common today. It uses 2 integrated circuits to...
We found this circuit in Popular Electronics from 1992. Transistors admit equivalents....
This circuit can be used to directly control direct current loads or higher alternating current loads...