Jan Lategahn (Germany) has put together a series of articles and links describing simple ways to calibrate amateur electronic instruments with a fair degree of accuracy without having to spend a bundle on a professional calibration lab. Methods and devices include DC and AC voltages, resistance, current, RF level, and frequency. Above are Jan’s homemade resistance and DC reference voltage calibrators.
Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner's Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.
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Temperature has an effect on resistors and semi-conductors. http://en.wikipedia.org/wiki/Electrical_resistance#Temperature_dependence
It doesn’t look like this system take it into account, so just how good can it be as far as precision calibration?
Just like most calibrations (volume, pressure, etc), there are other factors that need to be considered.
I disagree that this is not good for calibration. If you read Jan’s website, you will see they are more than adequate problems he was trying to solve.
The voltage source uses an LT1021, which is temperature compensated to 5ppm/deg C. Since it has an initial accuracy of about 500ppm, I think you can ignore the temperature effects on this one. This standard is good enough to calibrate a 3.5 digit meter to +- one LSD.
His Resistance standard has a stated accuracy of 0.1% (1000ppm). Typical resistors of that spec are 25ppm/deg C at worst. Digikey stocks 10ppm parts for more money.
Are they NIST traceable, standards lab quality? No. But I think these would be very useful for any hobbyist.
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