This 5 V circuit was found in December 1978 Radio Electronics magazine. The power transistor must be mounted on a good heat sink.
For analog lines, this circuit was found in the August 1994 issue of Electronics Now magazine. The...
This circuit has a traditional configuration often found on this site. The transistor must be...
This 4-digit counter, using CMOS technology, was found in a 1997 documentation. The circuit is...