This is the typical circuit of a local oscillator for a superheterodyne FM receiver. The circuit was found in a 1980s documentation and is typical of early and early receivers.
This tone recognizer circuit that relies on R5 and C1 was found in the December 1994 issue of...
Found in a RCA publication from the 1970s, this circuit is intended for the production of pulse...
This is basically the same circuit as the previous one, but using PNP transistors. In the original...