• on Test & Measurement
  • Published in issue 5/2009 on page 48
About the article

V & I Calibrator

Have faith in your measurements

V & I Calibrator
It’s difficult to be sure that your digital multimeter (DMM) is taking accurate measurements especially if it’s a few years old. This handy calibrator gives full scale reference levels of both voltage and current, designed specifically for the scale ranges used by DMMs.
DMMs which claim to have a basic accuracy better than 1% can these days be found for less than £20. Even instruments with better than 0.5 % accuracy are selling for less than £100.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Extra info, Update
Technical Specifation
• 0.1 % accuracy at 25°C
• Temperature stability: 50 ppm/°C
• Output voltage: 3.9 V/1.9 V switchable
• Output current: 3.9 mA/1.9 mA switchable
• Power requirements: 6 to 18 VAC or 9 V battery
• Current consumption: 5 mA
R1 = 1k?5, SMD R1206
R2 = 3k?9, 0.1%
R3A = 68k?, 0.1%
R3B = 10k?, 0.1%
R4A = 2k?7, 0.1%
R4B = 680?, 0.1%
R5 = 1k?, 0.1%
C1 = 100?F 35V, radial electrolytic
C2 = 10?F 35V, radial electrolytic
C3,C4 = 100nF, SMD C1206
C5 = 10nF, SMD C1206
C6 = 1nF, SMD C1206
B1 = B40S, SMD bridge rectifi er, 40V/1A
IC1 = 78L05SMD, SO08
IC2 = LT1490, SO08
IC3 = LM4050A-4.1, SOT-23, e.g. Farnell # 1468851
JP1 = 3-way SIL pinheader, lead pitch 2.54mm (0.1”) with jumper
PCB, # 080894-1
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