This circuit for old analog telephones is from period documentation. It controls a relay that can be used to turn the extension on and off.
This preamplifier for magnetic cartridges was found in the February 1990 issue of Radio...
This oscillator for receiving SSB signals is intended for receivers with IF of 455 kHz. The...
This simple transmitter for the citizen range was obtained in a 1983 publication and has only one...