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Why not rectify the 9VAC

Submitted by Guest on Fri, 26/07/2013 - 18:43

Hi,

I am curious what the point is of sampling the 9VAC on the arduino to determine the wall voltage. Why not just rectify the AC voltage with some diodes, caps, resistors, scale it down and measure that? Then you could skip all the software steps of sampling the voltage and just read a DC voltage on the arduino?

Thanks

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Robert Wall's picture

Re: Why not rectify the 9VAC

Submitted by Robert Wall on Fri, 26/07/2013 - 20:02.

The rectified d.c. voltage gives you no real information about the line voltage. You would lose the rms value (because it is not necessarily a true sine wave) and you lose all the information that the phase of the line voltage gives you - power direction, real power and power factor. You can read up on the theory in Building Blocks.

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