VLF Radio Receiver circuit

This version sports a 2nd audio amplifier stage at Q3. The output level with this version is sufficient to drive a crystal headphone to a comfortable volume. The `crystal` headphone is like those used on ye olde crystal radios. A `Walkman` type headphone is NOT the same thing! Check out Mouser #25CR060. Or use as input to your amplifier.
VLF Radio Receiver circuit - schematic

T1 is a Radio Shack 1K CT primary to 8 ohm secondary Only 1/2 of primary is used. Secondary is not used. NOTE: Output is microphone level audio. Schematic From: www.auroralchorus.com/bbb4b.htm See also: www.auroralchorus.com home page See also: www-pw.physics.uiowa.edu/mcgreevy/ C4/C5 values: See text on above web reference Rat Shack part number is 273-1380. D1/D2 Optional - protects Q1 from nearby lightning

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