Versatile DC Power Meter

Voltage, current, and even more

Published in issue 373, January 2008

Resistors
R1 = 27kΩ
R2,R3 = 27kΩ, 1%
R4 = 10kΩ, 1%
R5 = 10Ω
R6,R8 = 1kΩ 
R7 = 100Ω  0.1%
R9 = 10kΩ
R10 = 10kΩ 0.1%
P1 = 10kΩ preset
P2 = 100kΩ cermet preset
Precision shunt 1 m( 50 A, 0.5%* or 10 m(/5 A, 0.5%*, Isabellenhütte type PBV R001 or R01 (Conrad Electronics # 447315 or  # 447323)
Capacitors
(all 2.5mm lead pitch)
C1,C3-C7,C9,C12 = 100nF
C2 = 100µF 16V
C8 = 10nF
C10,C11 = 22pF ceramic
Semiconductors
D1 = 1N4004
D2,D3 = zener diode 7V2, 500 mW
T1= BS250*
IC1 = 7805 (TO220)
IC2 = LM335 (TO92)
IC3 = ATMega8PC, programmed for 4x20-LCD, order code 070559-41
IC4 = TL081P (DIL)
Inductor
L1 = 10µH
Miscellaneous
X1 = 8MHz quartz crystal
One 8-way turned-pin IC socket
One 28-way turned-pin IC socket
LCD 2x16 or 4x20, DIP, with backlight, Electronic Assembly (Conrad Electronics # 181755 resp. # 181863)
JP1 = (temporary) pushbutton
JP2,JP3 = jumper or wire link
JP4 = jumper or switch, 1 make contact*
U-profile heatsink, 12 K/W for TO220 (IC1)
4 M3i/M3a spacers, length 18mm
Two 10-way socket strip, lead pitch 2.0mm (remove 1 pin)
PCB, order code 070559-1
Project software and PCB layout freely downloadable from www.elektor.com
*see text