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Re: integrating true RMS wattmeter



Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 09:48 AM 3/26/2006, you wrote:

>>11) this circuit is darned simple - maybe we can use a couple of
>>additional elements to get real _electronic_ accuracy? : )

> Certainly. That design is 10 years old, at least.


can you (as much more educated electronic hobbyist than i was many
years ago :D) suggest something in that direction? or maybe totally
different (but still simply enough) approach (probably using modern
circuit technology)?


Depends.. If "I" were doing it, I'd do something that sampled I and V at a fairly high rate and used a microprocessor to do the calculation. The micro could also linearize and temperature compensate the current and voltage measuring circuits, and could generate useful other data (harmonic content, power factor, etc.). I've thought about using a stereo sound card as the digitizing interface, but I'm not motivated enough to leap into Windows audio handling.

Others might prefer to use one of the many instantaneous power measuring ICs that are available from Analog Devices or IR or Maxim. There's a fair number of single chip solutions for this very problem out there.