Weight or Load Sensor advice

Discussion in 'The Projects Forum' started by mattyl2003, Jan 7, 2013.

  1. mattyl2003

    Thread Starter New Member

    Jan 5, 2013
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    Hi

    I need some advice on what kind of sensor to use with my ardruino. I need a sensor that will detect if the slightest of weight was dropped onto it. It doesnt need to measure the weight or do anything special.

    So for example if a piece of paper was dropped onto the weight sensor it will register this and light up a LED thats it. Ive found a ton of load sensor etc, but nothing that will detect this light weight and for a reasonable price.

    Any suggestions on parts?

    Thanks in advanced guys.
     
  2. mattyl2003

    Thread Starter New Member

    Jan 5, 2013
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    Nothing???.. i am sure there is someone out there whocan give some advice on which sensor pad to use for a light weight project
     
  3. bertus

    Administrator

    Apr 5, 2008
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  4. mattyl2003

    Thread Starter New Member

    Jan 5, 2013
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    Thanks for the reply,

    Am after something much smaller like the size of a plating card foe example and can measure paper weight.

    Cheers
     
  5. KnRele

    New Member

    Jan 7, 2013
    20
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    What about a little bit of the conductive foam that ICs are stored in? This stuff is resistive and if you put it between two metal plates and load it down it will change its resistance.

    However, like any of the other possibilities listed, it might not be sufficiently sensitive -- a sheet of the commonly used 80 g/m^2 A4 paper weighs 5 g -- maybe some kind of lever-action could be used to improve sensitivity?
     
  6. tshuck

    Well-Known Member

    Oct 18, 2012
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    You aren't measuring weight, so why constrain your sensor to just weight? Why not use an IR sensor coupled with an ultrasonic sensor(two to compensate for the shortcomings of each sensor)?

    If you really want to go for weight, you could construct a hydraulic lift to redistribute the force to another piston with a force sensor.... basically as a force amplifier...http://www.physics247.com/physics-tutorial/pascal-principle.shtml
     
  7. WBahn

    Moderator

    Mar 31, 2012
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    Kitchen scales typically have resolutions in the 1g range and Amazon presently has one that has 0.1g resolution and sells for only $3.51 (with free two-day shipping for Amazon Prime members). At that price you can do a lot of experimenting with ripping the load cell out it.
     
  8. mattyl2003

    Thread Starter New Member

    Jan 5, 2013
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    Thanks for the replies.

    Is it true that load cell sensors and strain gauge are all analog sensors?
     
  9. strantor

    AAC Fanatic!

    Oct 3, 2010
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    as far as I know, yes....
     
  10. WBahn

    Moderator

    Mar 31, 2012
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    A strain gauge (most of them, not all) is, at the end of the day, nothing more than a wire whose resistance changes when it is stretched. Most load cells are nothing more than mechanical devices that have strain gauges mounted on portions that bend under load.
     
  11. Metalmann

    Active Member

    Dec 8, 2012
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    I was thinking along the lines of Postal Scales.:


    http://www.officedepot.com/a/browse...ssionid=0000-4zrEBZwofoCubnjOIH1PWB:13ddq0tng
     
  12. BillB3857

    Senior Member

    Feb 28, 2009
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    Do you have a link to this? I couldn't find it on Amazon but may not have known exactly where to look.
     
  13. WBahn

    Moderator

    Mar 31, 2012
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    I hadn't thought of that, but definitely worth consideration. I suspect they will be significantly higher in price since they are intended for commercial transactions, but will probably be more reliable and accurate, as well. I did a quick check and on most of them I couldn't find resolution specs. The one I did find it on said 0.1oz, which is about 3g. So the resolution is on the level of a piece of paper, which may not be good enough.
     
  14. WBahn

    Moderator

    Mar 31, 2012
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    I just did a google search for "food scale" and followed the Amazon link that came up.
     
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