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Author Topic: Live tracking weight changes  (Read 379 times)
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Hi guys, I have a somewhat unique idea that I'd like to get some guidance on. I've done some basic arduino stuff, actually interfaced the arduino with twitter but what i'd like to do is monitor water consumption based on weight.

I'd like to have a scale weigh a water cooler and monitor consumption. My idea is that you have a weight empty and weight full... you also monitor for changes in weight of a certain amount, this way you can track consumption. I have an idea of how to monitor changes but no idea what inputs to use. Is there any type of load sensor out there suitable for this? I'd also imagine i'd need a few distributed? Any ideas or any experience? Thanks guys!
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This site lists load cells that look as if they are probably suitable for what you want
http://www.alibaba.com/product-gs/672691783/High_accuracy_load_cell_10kg_20kg.html
You should check price, minimum order quantity, how you interface to the cell and that it will do the job you want.

From a quick look the applications they mention, the weight ranges and the platform sizes all suggest they might be suitable for what you have in mind.
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You might could use force sencing resistors like below.


https://www.google.com/search?num=100&hl=en&lr=&tbo=d&as_qdr=all&q=fsr+force+sensing+resistor&oq=fsr+resistor&gs_l=serp.1.1.0j0i7j0i7i30j0i7i10i30j0i7i30l3.11644.13365.0.19594.2.2.0.0.0.0.125.207.1j1.2.0.les%3B..0.0...1c.1.nYQNn85f7Gs
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Not very good choice if any kind of accuracy is needed:

Quote
Compared to other force sensors, the advantages of FSRs are their size (thickness typically less than 0.5 mm), low cost and good shock resistance. However, FSRs will be damaged if pressure is applied for a longer time period (hours). A disadvantage is their low precision: measurement results may differ 10% and more.

http://en.wikipedia.org/wiki/Force-Sensing_Resistor
Lefty
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Get a digital bathroom scale and disassemble/reassemble it enough until it fits your water cooler nicely. Then either hack into the onboard electronics (sometimes the amplified reading from the load cell is available) or replace those electronics with an instrumentation amp. If you need more then the 10bit accuracy provided by the Arduino's ADC then you'll also need a different ADC to go with it.
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