# How to calculate average power, ac superimposed on dc voltage.

Discussion in 'The Projects Forum' started by AbhimanyuSingh, Jun 11, 2011.

1. ### AbhimanyuSingh Thread Starter New Member

May 22, 2011
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What should be the best way to way to calculate the average power across a resistive load for the voltage form shown in the image attached?

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2. ### #12 Expert

Nov 30, 2010
16,685
7,325
Imagine a horizontal line through the center of the sine wave and call that voltage.
The, P = E squared over R

Jul 7, 2009
1,585
141
First digitize it. If you want the average, then use the definition of the average: just sum up the points and divide by the number of points.

Instead, you might want to consider the RMS value instead: square all the values, average them, then take the square root.

Then it's the usual V^2/R calculation.

4. ### ErnieM AAC Fanatic!

Apr 24, 2011
7,436
1,626
Your spice program can't do power?

I'd just ignore the AC component until I had a real breadboard to measure what the signal really looks like.