I2C Interface / Current Sensor

My friend and I are 10th grade students at a Governor's School for Science & Technology. We are in a class called Product Development Engineering. For our project we want to detect current flow from 110V AC household outlet to an electrical appliance and pass the measurements using an I2C bus and then USB into a laptop. We've found the perfect product on the Internet: http://www.raztec.co.nz/series3.html.
We have not gotten a response to our inquiries to this New Zealand based company so we are looking for equivalent products that we could get in the US. We are hoping you could help us in suggesting something similar. This Raztec product uses the Hall Effect to measure the current and has a built in ADC and the I2C bus. One version of their product can handle up to 80amps which would be more than adeqate. Thank you! Ev and Em

What part of the world are you in? Many times country of origin determines parts availability.

What kind of resolution are you looking for? I assume USA standards, which would be 15 to 20 Amps at 120VAC. Is .1 Amp steps good enough?

Bill_Marsden said:

What part of the world are you in? Many times country of origin determines parts availability.

What kind of resolution are you looking for? I assume USA standards, which would be 15 to 20 Amps at 120VAC. Is .1 Amp steps good enough?

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We are in the USA. Yes to your other questions. We also would prefer an I2C bus / interface but if that is not possible any recommendation would be appreciated.

To give you a bit more info: Our project involes creating a product that would notify the user when their clothes dryer has finished its cycle. In designing this device, we are attempting to monitor the current of the dryer in order to send a signal to a computer once there is no current detected. From there, the computer will either call a cell phone or a pager.
We have ordered a QBridge I2C USB host adapter http://www.qprotos.com/datasheet/QBridge_I2C_USB_1.1.pdf
but need the second part of the equation OR a different solution.

Thank you very much for your reply.

See my note about Elektor USA in this thread

http://forum.allaboutcircuits.com/showthread.php?t=15188

Eklektor ar fundamentally a showcase for Philips, who invvented the I2C bus and they have a long history of I2C bus projects and explanations. They might even publish your project.

Good luck.

I like the concept, though can't help with the computer side much. I'll be following this thread with interest. You might even have a comercially viable product.

The Kill-A-Watt is a small package to do all of that, but has no provision for data logging. Might be possible to rummage around in one, though.

you can easily make an analog current sensor using a ferrite ring and an analog output hall effect switch, similar to this product >> http://search.digikey.com/scripts/D...ge_link=hp_go_button&KeyWords=CSLA2CD&x=0&y=0

But if you use a split ring ferrite core then you can make a clamp on version to where you wont have to run the wire through it, you can just clamp it on. This will enable you to keep your circuit completely isolated from the mains. Get yourself a microcontroller that can do USB (AVR,PIC, etc), and that also has ADC's, and you could build it all yourself.