Date: July 29, 2002 Sheet 1 of 1

Size Document Number REVB 0

RX Frequency Range: 100 Hz - 11 kHz

McGreevy VLF Radio Receiver

B19VS1

POWER

+9V

+ -

2N3904

+9V

+9V

R1110K

R710K

+9V

+9VSEC

+9VANTENNA1-3M WHIP

2N3819

G DS

Q1 Detail

R11M

C1

0.1

C9100

C100.1

Q12N3819

C30.1

R41K

0.0V

3.395V

N/C N/C

N/C

C5.0033.0047

C4.0033.0047

C6

0.1

T1RADIO SHACK273-1380

Q22N3904

R533K

R64.7K

C80.1

1.13V

5.89V

1.11V

5.81V

Q32N3904

C100.1

R933K

R104.7K

J1

Output

0.505V

C91 ufR121.5K

C71 ufR81.5K

0.492V

relative to ground.

R210M

R3220

1.295V

Typical ooperating voltages shown,

C247 pfD1

3.9V

D23.9V

This version sports a 2nd audio amplifierstage at Q3. The output level with thisversion is sufficient to drive a crystalheadphone to a comfortable volume.The "crystal" headphone is like those usedon ye olde crystal radios. A "Walkman" typeheadphone is NOT the same thing! Check outMouser #25CR060. Or use as input to youramplifier.

D1/D2 Optional - protects Q1 from nearby lightning

T1 is a Radio Shack 1K CT primary to 8 ohm secondaryOnly 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 pageSee also: www-pw.physics.uiowa.edu/mcgreevy/

C4/C5 values: See text on above web reference

Rat Shack part number is 273-1380 Documented by Tom Farrand

VLF RECEIVERVLFRX.SCH