electricity meter to a picaxe to twitter!

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mark.duyvesteyn

Member
using an 08m, some python script and an LDR i am measuring the flash from the led on my electricity meter, converting it to cent and posting the result to twitter. From twitter u can graph the usage and keep a track of things. Have a look the twitter page, www.twitter.com/AtOurHouse

just started before after some playing round, so ignore the crazy readings and other stuff. will prob make the posts each hour, and make the picaxe send a daily total or something

if any one wants to know more ill post some links and code :)
 
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atharvai

Senior Member
hey nice project.

i was looking to make something similar. well the same but instead of posting it online i was thinking of locally charting the data. any pointers on equipment used would be helpful

did u use some sort of hall effect sensors on ur main line to measure the usage?
 
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mark.duyvesteyn

Member
i was looking into using the hall effect sensors e.t.c but it was heaps easier to go off the flashing LED on the meter its self. It flashes proportional to the amount of power used. Its says 800imp/KWh beside it, so i assume that this means that it pulses 800 times for every kWh used. Using An LDR i measured and counted the pulses, converted them to cents and Watt-hours. the LDR is just taped in front of the LEd on the meter. All of it is running off a little proto board plugged into a laptop using a serial cable. When i figure out how to run the python stuff on OSX i will put it on my media PC which is on all the time anyway.

i just tested it then and turned on a few lights and the oven for a few mins, and the readings jumped right up!
 
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atharvai

Senior Member
ah i see. my meter is quite old and doesn't have a flashing LED or anything. i will have to look into hall effect sensors or some other method.

i had a question about python. I'm not familiar with python as a language. is this for use on PCs or uprocessors?

cheers
 
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mark.duyvesteyn

Member
i know virtually nothing about python - 1st time ive used it was today

i just found a few bit and pieces on the net and mashed them together. it runs on windows, OSX, Linux e.t.c. in this case all it was doing is looking for serial data from the com port, and then forwarding it to twitter.
 
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boriz

Senior Member
@ Atharva

I also have the old rotating disk type. It should be possible to use an optical method:

Focus an LED (or LASER pointer) on the edge of the disk and use a phototransistor to count the marks as they move by.
 
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mark.duyvesteyn

Member
the usage just went way up, which was strange because i was the only one home...

Then i realized light must have been getting into the LDR and throwing off the values by counting more pulses (i installed it last night in the dark - white insulation tape doesn't block much light :p)
 
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krypton_john

Senior Member
mark.duyvesteyn said:
i was looking into using the hall effect sensors e.t.c but it was heaps easier to go off the flashing LED on the meter its self. It flashes proportional to the amount of power used. Its says 800imp/KWh beside it, so i assume that this means that it pulses 800 times for every kWh used. Using An LDR i measured and counted the pulses, converted them to cents and Watt-hours. the LDR is just taped in front of the LEd on the meter. All of it is running off a little proto board plugged into a laptop using a serial cable. When i figure out how to run the python stuff on OSX i will put it on my media PC which is on all the time anyway.

i just tested it then and turned on a few lights and the oven for a few mins, and the readings jumped right up!
Click to expand...
Hey Mark, that is pretty cool. We have a meter that is only 4 years old - I must check and see if it has the flashing thingy.

To complete this you need to add a 433Mhz rf transmitter so you don't need a cable from the meter box to your PC!

Cheers
JohnO
 
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mark.duyvesteyn

Member
update

i found a python script which lets you interface with google docs, so now i am uploading the data to a google spreadsheet so i can plot usage. This would be great for off site monitoring of temp e.t.c.
 
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moxhamj

New Member
Sounds fantastic. Can you explain a bit more about the python script? Is this running in a router or on a PC or on something else? Some photos too as this is the sort of project that should be in the 'completed projects' section. And maybe an Instructable too. Very nifty.
 
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mark.duyvesteyn

Member
update

here my google page, sorry about the resolution of the graph, i've made it that big to display on the TV.

http://sites.google.com/site/19acussen/

I have just started the data feed so will take a while before trend lines are established. The scale along the side don't mean much, it is the counter of the flashes in few minutes time frame.

it seem to be quite accurate, it will pick up if the tv is turned on or off e.t.c.

In america google is partnering with a few electricity companies to bring this kind of thing to the general public http://www.google.org/powermeter/howitworks.html its in beta at the moment.

will try make an instrucatble as well, its a very easy and rewarding project!
 
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MPep

Senior Member
Mark,

Look in the Finished User Projects, Communications area.
Check out Steliosm's posts. He provides code samples etc for sending to Twitter and the like.

MPep.
 
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mark.duyvesteyn

Member
fixed it and added dails :)

the top one is instantaneous power being used (how much it would cost to keep running like it is for an hour)

the second dial is actual cost for the last hour,

ad the last one is the average per hour for the last 24 hours (still waiting on more data)

I will add more things as i can think of them, for example power used yesterday vs power used today e.t.c.

http://sites.google.com/site/19acussen/
 
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atharvai

Senior Member
boriz: that is a possible method. i also read somewhere that its possible to use the mains socket to monitor the power flow or something.

the reason i look for hall effect sensors is because my meter is outside the house and i don't want to leave my picaxe and circuit there. i can hook up the hall effect sensors in my garden from where the main line comes.

i also thought of another silly method to do it. use a webcam, and OCR software to read the digits! a bit too extreme and not very efficient.

mark:good site, a few photos would be good aswell.

i was just wondering tho, if i make a coil out of some wire (don't know if i should be using certain type of wire) wrapped around the main supply cable, it will give me a current proportional to the usage? and thus a proportional voltage?
 
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