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Tweet-a-watt - How to make a twittering power meter...

This project documents my adventures in learning how to wire up my home for wireless power monitoring. I live in a rented apartment so I don't have hacking-access to a meter or breaker panel. Since I'm still very interested in measuring my power usage on a long term basis, I built wireless outlet reporters. Building your own power monitor isn't too tough and can save money but I'm not a fan of sticking my fingers into 120V power. Instead, I'll used the existing Kill-a-watt power monitor, which works great and is available at my local hardware store.

My plan is to have each room connected to a 6-outlet power strip which powers all the devices in that room (each kill-a-watt can measure up to 15A, or about 1800W, which is plenty!). That way I can track room-by-room usage, for example "kitchen", "bedroom", "workbench", and "office".

Each wireless outlet/receiver can be built for ~$55 with a few easily-available electronic parts and light soldering, no microcontroller programming or high voltage engineering is necessary!

You can see my setup including graphs and reports at http://twitter.com/tweetawatt

If you'd like to build one for yourself

1. Buy a kit: get all the parts you need, there's a starter kit at the adafruit webshop
2. Make: turn each Kill-a-Watt into a wireless power level transmitter
3. Software: Download & run it on your computer to get data and save it to a file and/or publish it

If you want to know how it was made, check out:

1. Listen: write simple software for my computer (or Arduino, etc) to listen for signal and compute the current power usage
2. Store: Create a database backend that will store the power usage for long-term analysis at http://wattcher.appspot.com
3. View: Graph and understand trends in power usage

Check out the latest readings at http://wattcher.appspot.com

Step 1: Make it!

Before you start...

You should only attempt this project if you are comfortable and competent working with high voltage electricity, electronics and computers. Once the project is complete it is enclosed and there are no exposed high voltages. However, you must only work on the project when its not plugged in and never ever attempt to test, measure, open, or probe the circuitboards while they are attached to a wall socket. If something isn't working: stop, remove it from the wall power, then open it up and examine. Yes it takes a few more minutes but it's a lot safer!

Your safety is your own responsibility, including proper use of equipment and safety gear, and determining whether you have adequate skill and experience. Power tools, electricity, and other resources used for this projects are dangerous, unless used properly and with adequate precautions, including safety gear. Some illustrative photos do not depict safety precautions or equipment, in order to show the project steps more clearly. This projects is not intended for use by children.

Use of the instructions and suggestions is at your own risk. Adafruit Industries LLC, disclaims all responsibility for any resulting damage, injury, or expense. It is your responsibility to make sure that your activities comply with applicable laws.

OK, if you agree we can move on!

Make a tweet-a-watt

To make the tweet-a-watt setup, we will have to go through a few steps

1. Prepare by making sure we have everything we need and know the skills necessary to build the project
2. Build the receiver setup by soldering up one of the adapter kits
3. Configure the XBee wireless modems
4. Build the transmitter setup by modifying a Kill-a-Watt to transmit via the XBee
5. Run the software, which will retrieve data and save it to a file, upload it to a database and/or twitter
Cool hacking... <br /> <br /> <br />I just want to inform you that we also posted your project on our Arduino facebook page...Feel free to join us and answer community questions. <br /> <br />http://www.facebook.com/faceuino <br /> <br />Sincerely, <br />Faceuino team
My Kill A Watt has its bits behind the LCD screen. (AAARRRRRGGGHHH!!) Apparently its gone thru some kind of revision :(
I just got a Kill-A-Watt and took it apart. It still has an LM2902 but it is on the other side of the PCB. You have to remove the PCB that is attached to the display and buttons.<br>This LM2902 is a surface mount version, so the spacing between the pins is smaller and you would have to use smaller wires but it is probably still doable if you have good soldering skills and a soldering iron with a small tip. <br><br>I just noticed that the LadyAda website has an update for this:<br>http://www.ladyada.net/make/tweetawatt/solder.html<br><br>Lazy Old Geek
&nbsp;My P4400 kill a Watt serial no. YBJA2077 &nbsp;which I purchased a few months back does not have the LM2902 chip any place that I can see it ... so it looks like this project is now a no-go !!!
I just got a Kill-A-Watt and took it apart. It still has an LM2902 but it is on the other side of the PCB. You have to remove the PCB that is attached to the display and buttons.<br>This LM2902 is a surface mount version, so the spacing between the pins is smaller and you would have to use smaller wires but it is probably still doable if you have good soldering skills and a soldering iron with a small tip. <br><br>I just noticed that the LadyAda website has an update for this:<br>http://www.ladyada.net/make/tweetawatt/solder.html<br><br>Lazy Old Geek
We built four of these after seeing in MAKE magazine and on Adafruit. Lots of fun.&nbsp; We put one on our office coffee pot to tweet my cell phone when the coffee is ready. See <br /> http://twitter.com/tweetawatt1<br />
&nbsp;Sweet I was unaware I could get a KaW locally, thanks for the heads up!<br /> <br /> <br /> Great 'structable btw ;)<br />
Hi, very nice and really comprehensive instructable.<br /> Is it possible to use this to tweak consumption reading from electric companies? I know aroun here (argentina) thew tweak the turning weel on the meter. Obviously iligal. but just for imformation purpouses.<br />
Hey, this is a great project, all the instructions are very well explained. I made for only one transmitter, but now I am planning to build several in order to get a better control of my electricity consumption. congratulations
This is without a single doubt in my mind the best, most creative, and most extensive instructable I have ever seen since first discovering instructables.com! 5 Stars right off the bat and cheers to your hard work, Ladyada! Also like the additional router section (compared to the MAKE article which didn't have it).
hey, you should make a CD with all the software and coding on it, it might help you sell kits!
Ha Yeah,He Would Probably Need DVDs To contain all that Data/Programs/Coding/EXT
This must have taken awhile to write, good job....
Very Very good excellent your details your pictures perfect. Congratulations
Is there a way to wire it (phone line/ethernet) to cut down costs?
this is still great but have i seen it somewhere before? (this is the original right?)
awesome. i was totally thinking of doing something like this but i wasent at all sure how with the wireless info to the laptop. but now....... i am informed. and will start this project most likley in the next few weeks. thanks for all your hard work.
well thats cool
instead of tweet a watt call it a twat...JOKING..calm down. nice ible
Great Instructable , I hope i could do things like you : ) Congrats
Very nice repackaging of your excellent MAKE article! The additional assembly details and pictures are most appreciated.

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Bio: All-original DIY electronics kits - Adafruit Industries is a New York City based company that sells kits and parts for original, open source hardware electronics projects ... More »
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