Tweet a watt enquiry

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sinan
 
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Joined: Mon Feb 08, 2010 11:53 am

Tweet a watt enquiry

Post by sinan »

Hi All,

Would it be possible to answer these questions?
1. I live in Malta / EU. Our plugs are different than what kill a watt comes with, do you know where I could get a kill-a-watt already in the version (our plugs are called Type G http://en.wikipedia.org/wiki/AC_power_plugs_and_sockets). Worst case would be to use adapters :(

2. Can one buy ready made tweet-a-watt with Xbee integrated and working? Please direct me to where/who.

3. Do you have plans to improve this module and software for instance i. add remote power on/off by software commands to the tweet-a-watt ii. inform tweet-a-watt to what it is connected to (for instance a fridge) and put in max power requrements in order to authorize tweet-a-watt to cut the power if more current is drawn and stop a potential fire.

Kind regards,
Sinan
+35699447120

adafruit
 
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Joined: Thu Apr 06, 2006 4:21 pm

Re: Tweet a watt enquiry

Post by adafruit »

1. you would have to get a local version of the k-a-w. they probably have something for sale, but we dont know since we are in the US
2. adafruit only sells kits
3. not at this time, the project is 'as is'

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richms
 
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Re: Tweet a watt enquiry

Post by richms »

I have tried with a locally available meter that does the same as the KAW to do a tweet a watt - it was made by elto but it looks like its a chinese OEM product so they probably make it with many plugs and sell it to many places.

I have seen a UK plug meter that did the same thing as the kill a watt so that would be a good start. I think it was on asda's website.

In anycase I had the following problems.

firstly, the opamp was a SMD one.

Then, the signals are in different places. Hard to find since the whole thing is live with respect to ground without an isolation transformer so you dont blow yourself or the gear up.

Then, the signals were _much_ smaller than in the KAW - 100mV so I would have to change the reference for the ADC in the xbee

Then, they were biased up somewhat, which meant that the resolution I was getting was BANNED since most of it didnt change. I may have been able to make some level shifting stuff to get it going 0-3v to make it work better into the xbee.

Then, the waveforms were rectified, so they looked like a nasty 100Hz wave rather than a 50Hz sinewave. This and the offset stuffed up Limor's softwares ability to use them. I could calibrate it to be exactly right on the heater, and then something else would start to say 2 kilowatts etc.


Then I went to get another meter after blowing up the one I had thru shear stupidity only to find the guts are totally different now. The new one is more hopeful since rather than a op-amp, the chip is one that is designed for digital metering, and has a SPI connection to the second board with the display on it. From using it standalone is it a _LOT_ more accurate than the previous one, so if that level of accuracy can be read wirelessly I will be very happy, but as it is SPI, then I would need an arduino or similar in it replacing the existing display board.

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Franklin97355
 
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Re: Tweet a watt enquiry

Post by Franklin97355 »


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