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.
This circuit came out in a publication called Electronics Handbook of 1993. The circuit shows how...
Found in documentation from the 1980s, this circuit makes use of general-purpose diodes and...
This circuit memorizes through an LED indicator if your phone was used during your absence. The...