This circuit for audio applications was found in an English magazine from the 80's. The circuit has a pass band below 3 kHz making it ideal for telecom applications.
We found this crystal AM radio using a germanium diode in a Japanese magazine in 1967. The circuit...
This filter was found in Radio Electronics, and its configuration can be applied to any...
This circuit was obtained in an old English magazine (TSI) 1998 and consists of a Schmitt trigger...