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Author Topic: Flexiforce sensor with arduino, and only +5 volts  (Read 1991 times)
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I need help modifying the following schematic to accommodate essentially the arduino power and nothing else. I tried switching the flexiforce pin from the inverting pin to the non-inverting pin of the op amp then powering it with +5v, but that did not work. I don't know the first thing about designing circuitry, so any help is greatly appreciated. I have done tons of googling with no luck.

If I have to use circuit, how I can get a -5 volt supply out of the 5v supplied on the arduino?

Thanks to anyone who can help me, I have been trying to solve this on my own for a couple days.

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You could just make the flexiforce sensor one of the 2 resistors in a standard voltage divider:

http://en.wikipedia.org/wiki/Voltage_divider

You will get a less linear characteristic between voltage and applied pressure, but no op-amps required!

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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, speaker, microphone, light sensor, potentiometer, pushbuttons
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That is actually how I had it set up initially for testing when I was using a less sensitive force sensor. I am now using the 100 pound sensor I plan to use with my project. This one is just so insensitive though, I figured I would set it up the way the schematic told me to. I am using a 10k trimpot shown below for my project. Maybe I need a larger trimpot (100k) to get the results I need? I could probably whack it with a hammer and have it barely light up the reference LED. I need it more sensitive than that lol.

http://www.sparkfun.com/products/9806
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See this

* sloa058.pdf (163.12 KB - downloaded 33 times.)
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see this also, i can work for you

* 1.pdf (121.1 KB - downloaded 54 times.)
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 Thank you very much for that! Is that IC this op amp?

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yes LM741
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