With this circuit from the September 1989 issue of Radio Electronics magazine, it is possible to receive VLF band signals on a common radio, just like the signals emitted by the previous receiver.
We found this circuit in the Linear Applications Handbook of the National Semiconductor of 1994....
This tone-modulated transmitter was found in recent English documentation. The circuit operates in the 27...
This very low current circuit was found in the April 1995 issue of Electronics Now magazine. The...