[TriEmbed] TriEmbed Digest, Vol 20, Issue 11

[Mark Sidell]

If I'm not mistaken, the Arduino circuit described measures apparent power,
not true power, because it simply averages the current and doesn't take
into account the voltage to current phase shift caused by inductive loads.
Good enough to tell if your water heater is on, but it may not match what
your electric meter says.

On Wed, Jan 14, 2015 at 9:49 PM, Martin Brooke <martin.brooke at duke.edu>
wrote:

> I used an audio jack breakout on an arduino proto shield with a simple RC
> circuit to level shift the AC.
>
> here is a photo
> <https://drive.google.com/file/d/0B0lP-6BNGel_a09EbFBkeDJWamc/view?usp=sharing>.
> The proto shield is this one from  sain smart
> <http://smile.amazon.com/SainSmart-Prototyping-Prototype-Breadboard-Arduino/dp/B0079WI2MK/ref=sr_1_4?ie=UTF8&qid=1421289842&sr=8-4&keywords=Prototype+Shield> although
> there are many alternatives for this.
>
> The break out was from sparkfun <https://www.sparkfun.com/products/10588>
> for which you need some headers <https://www.sparkfun.com/products/116>and
> the jack <https://www.sparkfun.com/products/8032>  maybe you can find one
> assembled
>
> There is also two resistors and a capacitor needed to get the AC signal
> into the ADCs input range.
>
> I really just copied the circuit from this intructable
> <http://www.instructables.com/id/Yun-based-Electricity-Monitor-with-Cloud-Support-T/?ALLSTEPS>
> .
>
> The instructable goes way further, using an Arduino Yun to make it
> readable via wifi, very cool, but maybe beyond what you want or need.
>
> Cheers,
>
> ​​
>
>
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