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electricity data logger

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Posted by Burlington Bertie on February 28, 2007, 3:13 pm
Just got myself a data logger. This is an 8 channel unit which records
data from a variety of sources, but what I'm trying to do is download
household electricity, gas and water consumption with a view to
recognising waste. My aim is eventually to use it in a commercial

The gas and water metering is up and running. Both the meters put out
a pulse which is translated into a volume. It's already amazed me how
wasteful we are at certain times.

Electricity is harder, as I persuaded my utility company to install a
new meter with a pulsed output, but it's not an electrical signal as
I'd hoped but a flashing light. Every flash is 1/10th of a KWH. I need
to build a device which responds to the flashes and converts into an
electrical signal.

A phototransistor comes to mind but I've no idea how to do this. Can
anybody help?

Posted by LM on February 28, 2007, 6:28 pm
Burlington Bertie wrote:

There is a guy in Holland who automated his house to the extreme, i.e.
he tracks how many times the fridge is opened and how many times the
toilet is flushing for example!

Anyway, I visited his site quite a while ago and noticed he built a
gadget to sense the light pulses from the meter. If you are handy with
electronics this is one way to do it...
http://www.bwired.nl/How.asp  Click on el. meter link.

Good luck.


Posted by (PeteCresswell) on February 28, 2007, 7:10 pm
 Per LM:

This touches on something that I've obsessed about in the past.

Seems to me like every electric meter should be putting out a WiFi, Bluetooth,
or some other signal continuously.    

That would enable the creation of a wireless "home speedometer" that could be
put anywhere in the house like a wireless thermometer.    

My thought is that once people can easily and quickly see how much electric
they're using, they'll become much more conscious of waste...  

It's certainly had that effect on me since fooling around with the Kill-A-Watt
product just on my computer work station

I'm *still* wondering what the "idle speed" of my house is....

Posted by Martin Riddle on March 1, 2007, 12:18 am

Some one has this allready, I forget where. Search the Cnnmoney website.
wasnt that long ago, a week or 2. The device is a ring that goes around the
meter and counts the revs of the wheel by reflecting light off it.


Posted by Neon John on March 1, 2007, 5:04 am

Contact closure and RF output (NOT wifi or bluetooth) is available if
you're willing to pay for it.  A typical utility meter costs <$0 in
bulk so not much comes with it.  

Nah, already tried.  During the first oil embargo I worked with an
inventor to implement his invention.  His idea was a unit that clamped
onto a power meter, counted the dial revolutions by optically sensing
the zero flag on the meter dial and converted that to useful stats
such as instantaneous power usage, usage to date on this billing
cycle, etc.

I designed him the hardware and he tried to market it. Big flop.  No
market for it.  People don't really care.

This was a time when the Z80 was the state-of-the-art processor so the
gadget could be made much cheaper than back then but I still think
that there would be little interest.

That's easy enough.  Get out your stop watch and go to your meter.
Count the dial revolutions over a period of time.  Multiply those
revolutions by the Kh factor printed on the dial face (the number of
watt-hours per dial revolution) and divide by the time in hours to get
average KW.  or just total the revolutions and multiply by Kh to get
the KWh over the time interval.

John De Armond
See my website for my current email address
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain

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