This circuit converts signals from the shortwave band to the 118 to 130 MHz VHF band used in aviation. The circuit uses a 55 MHz crystal. We found it in documentation from the 90s.
This well-known siren configuration using complementary transistors is from a 1980s documentation. The...
This circuit was found in an old American magazine and could make use of more modern components...
This circuit is from the Philips integrated circuits manual of 1990. It is intended for magnetic...