http://www.electroschematics.com/5921/m ... ld-sensor/http://www.electroschematics.com/796/ma ... eld-meter/Magnetic Field Meter Magnetometer Circuit
Circuit Parts list 
Resistors:
 R1, R9, R11*, R14 = 10 kOhm
 R2*, R5, R7* = 1 kOhm
 R3*, R6, R16 = 100 kOhm
 R4, R8 = 1 MOhm
 R10, R12 = 22 kOhm, 1%
 R13 = 100 Ohm
 R15 = 6.8 kOhm
 R17 = 3.9 kOhm
 R18, R19* = 39 kOhm
 R20 = 82 kOhm, 1%
 * = 1% 
Capacitors:
 C1, C7 = 100 µF, 10 V, radial
 C2 = 10 nF, metallized polyester film, 5%
 C3 = 4.7 µF, 10 V, radial
 C4 = 10 µF, 10 V, radial
 C5 = 47 pF
 C6 = 2.2 µF, 10 V, radial
 C8 = 100 µF, 16 V, radial 
Inductors:
 L1 = see text 
Semiconductors:
 D1-D3 = LED, green, high efficiency
 D4-D6 = LED, yellow, high efficiency
 D7-D10 = LED, red, high efficiency
 D11 = 1N4148 
Integrated circuits:
 IC1 = TLC274
 IC2 = LM3915 
Miscellaneous:
 S1 = single-pole switch with make contact
 PC1-PC4 = soldering pin 1.3 mm dia.
 Bt 1 = battery 9 V
 Enclosure as suitable