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 circuit is from an Electronic Design from the 90's. The main integrated circuit is uncommon...
We found this circuit in an English documentation from 1995. With it it is possible to measure a...
Found on 90's Popular Electronics, this circuit triggers when the microphone picks up a sound. The...