This voice scrambler and descrambler circuit was found in a Radio Electronics from July 1963. Transformers are common types at the time with impedances according to telephones and line.
This 4-digit counter, using CMOS technology, was found in a 1997 documentation. The circuit is...
This circuit activates a relay that has a lamp as a load. The circuit is from a Radio Electronics from...
This circuit can measure frequencies up to just over 1 MHz and uses CMOS technology. The circuit is...