Found on 80's Popular Electronics this circuit operates at 455 kHz. The explorer coil is formed by 10 turns of yarn 26 in a 4 inch shape. The indicator is a microammeter.
This circuit uses a loop antenna to receive and amplify signals from the 60 kHz long wave band....
The frequency of this oscillator depends on R and C (see math section for electronics). The...
This common operational configuration can be implemented with modern equivalent. Next to the...