This circuit is intended to recover a very weak signal at a receiver, for example, a CW signal or a tone signal. The circuit is from a Popular Electronics from the 90s.
This 600-ohm output impedance circuit was found in a Radio Electronics from October 1963. The...
Used with infrared remotes at the time, this circuit was found in a 1991 RE Experimenter Handbook....
The circuit presented was obtained in a technical documentation from National Instruments. The...