$5 Power Meter





Introduction: $5 Power Meter

Lets build a $5 web based power meter and break open our usage to those with solutions to our antiquated grid and lifestyles.

This is a great start=> Real-time Web Based Household Power Usage Monitor
And here's a leading commercial product => TED

The device can serve residences, organizations, and communities trying to understand and reduce their energy use. .
The data will be hosted online so it can be audited by 3rd parties. The data might be hosted by Google's Power Meter and 3rd parties may gain access to market their energy savings solutions; such as, a new refrigerator, heating system, or efficient lights, etc.  

Why do it? well the utilities are not going to... (they're old and slow moving) and the smart grid is a hoax.... and it should be kinda fun to show up the expensive, commercial products available.

Would you like to collaborate on a potential disruptive product?

Step 1: What Has Been Done So Far.....

What has been done so far........

Well beyond the cool instructables that I've already mentioned..... here is where this project is at:

Fabricated a prototype PCB using the ADE 7757 power meter IC (see schematic)

ADE7757 $3.20 - digikey

ADE7757 Analog Inputs
The current sensor (CT sensor) goes to pins V2p and V2n and supplies a max differential voltage of +/- 30 mV to the on board ADC.
The voltage leads go to pins V1N and V1P to supply a max differential signal of +/- 165 mV to the on board ADC.

ADE7757 Analog Outputs
The ADE7757 is a high accuracy electrical energy measurement IC.  The ADE7757 supplies average real power information on low frequency outputs in the form of active low pulses with a relatively low pulse rate ~0.175 Hz.

A typical US residence requires qty(2) CT sensors to quantify energy usage. I've experimented with some inexpensive current sensors here.

Step 2: Programming

Read the Power
The CF pin on the ADE 7757 outputs a frequency. Here are two descriptions on how to read frequency using the Arduino Frequency Counter Library:
The Academy of Media Arts Cologne
Some list serve.......

Send the Power Data
Arduino Ethernet Shield and use the serverWrite() to send the data to any address. Is it really that easy?

Likely going to try to get a hold Google's API for their powermeter to help move the prototype along.

This guy hosts his own data here.  Its a pretty neat application that logs the data locally and provides a nice graph.
The only problem is you need a computer ON 24/7 to grab and record the energy data.  It would be nice for this data to be logged and displayed remotely.

Step 3: Design Goals

Design Goals


Grab real power in watts for the whole house usage (close to figuring out)

Broadcast the data over the home Ethernet/router to the hosted website (need to figure out)



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    i want to prepare a pcb layout using IC ADE7757 but I am unable to find the IC ADE7757 in eagle cad....It would be really helpful if you could give the .sch file for the schematic image

    Hi Anan,

    When I started this project 5 years ago I wasn't sure of what I was doing and I've learned a lot sense. I saw on digikey that this chip is still available but I'm not sure if it still the best chip to use and honestly I wasn't great a chip selection when I chose it. Regardless! to answer your question, if you look at the package type on the digikey website it says, 16-SOIC. This is a readily available package in the sparkfun library. I'm sorry no longer have the my original eagle library to give you but its super simple to grab the 16-soic from the sparkfun library and relabel the pins as needed. I think either sparkfun or adafruit have a good tutorial on this. Have fun! and good luck. -tom

    Thank you so much for the help..... Can you suggest me some other energy measuring ic... and why was ade7757 not a good chip selection

    i want to prepare a pcb layout using IC ADE7757 but I am unable to find the IC ADE7757 in eagle cad....It would be really helpful if you could give the .sch file for the schematic image

    now i dont know much about electrics but it would be cool if this sent the data through the power lines within the house and a box by the computer/router could collect it and send it through the web. It would just seem to me that if you were to use a wireless way then you might have to pay royalties

     The "real" $5 power meter.... is this some kind of contest? I like it.. Looks like your still missing some pages. keep up the good work. thanks,

     yea.. i use HOBO's all the time for work.  I'd love to see how it goes... please post it..  I suppose you just need to adjust the AAC/mVAC between that which is programmed into the datalogger and that which your 'amp clamp' operates at.

    You can just use a controlled load of some sort to perform the calibration.  Look forward to seeing how you do it.

    I have made an online power meter, using an LDR a few resistors and a picaxe.  All up it costs about $10.  The data is uploaded google spreadsheets through a  USB serial port on my mac mini, but any PC would do.  From there it is published on a google website and i display that website as a desktop picture on my HTPC.  Link to website is follows.  http://sites.google.com/site/19acussen/  Any questions email me at mark.duyvesteyn@gmail.com.