This circuit uses an MW radio tuned to around 540 kHz to detect atmospheric signals, for example, from an approaching storm. The circuit was taken from a Popular Electronics from the 90s.
In this circuit the capacitor under test is charged at switch position A and then discharged...
This is a common circuit in the 1990s, when experimental FM transmitters were in vogue. The...
Using a piezoelectric sensor of the time, this circuit was found in the February 1994 issue of...