Suggested by a 90s Popular Electronics this circuit is intended to receive volleys or whistles from thunderstorms in the wave range below 20 kHz. The coil consists of 300 turns of wire 26 in a ferrite rod.
This receiver for infrared remote control was found in the Philips Databook of 1990, The circuit...
Found in an English publication from the 1980s, this circuit uses components that are still common...
This circuit was found in Maxim's documentation from the 90's. The frequency of the circuit is...