This circuit works as both an injector and a signal follower. We found it in the May 1994 issue of Electronics Now. The Z1 headphone must be high impedance.
This circuit was found in a 1980s documentation. It decodes by identifying a certain frequency tone...
The purpose of this 2000 documentation circuit is to decode SSB (BLU) signals to be audible on...
This circuit was found in Electronics Handbook, Vol XIII 1993 and consists of a simple direction...