This circuit is from an article that teaches how to assemble it in the magazine Electronics Now from July 1993. It uses a liquid crystal display module from the time with 3 and a half digits.
This silencer or squelch preamp circuit was found in a documentation for radio amateurs. It...
This circuit has been found in an old American documentation and is intended for calibration of radio...
This circuit was obtained in a 90’s Popular Electronics. The frequency depends on C1, a component...