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 digital potentiometer is from a 1993 publication, but it can be easily assembled today. R1 to...
Maxim MAX16813B 4 Channel LED Driver These Maxim Integrated LED drivers are available from Mouser...
This circuit was found in an American magazine 73 for radio amateurs of the 80s. It is an...