This sensitive circuit was found in the June 1995 Electronics Now magazine. R1 can be from 10k to 1M depending on the desired sensitivity. Power is supplied by the relay.
This circuit, which can serve as a reference for restorations, was found in the October 1989 issue...
March 2017 - Mouser Electronics announces its new TPSA89 voltage regulator from Texas Instruments with...
The suggestion for using this circuit from an old American documentation is to use small antennas...