Tiny weight measuring sensors/scales

[electron]

I'm working on a small project, and I am trying to figure out the # of items in a small box (1"x1").  The items are very light weight, and I'm thinking weight would be the most accurate way of measuring the # of items in this box.
 
I am not sure if there is such thing as a cheap tiny scale I can integrate into the bottom of the box, but as crazy as this request sounds, I had to ask, in case I missed something obvious
 
Any suggestions?

 

[midon]

Dan,
 
You could try building something using this sensor http://www.seeedstudio.com/depot/weight-sensor-load-cell-0500g-p-525.html?cPath=144_150 or, just use a postal scale, or kitchen scale.  Integrating a pre-built scale into a 1x1 box would be a heck of a challenge though
 
Mitch

 

[electron]

Thanks for responding!
 
I don't think that load cell is sensitive enough, as the items are only a few grams each.  I could probably make the box as big as 3"x3", but haven't found anything small & sensitive enough.  I guess need to figure out a different way of measuring the # of items in this box.  I did find some Arduino code showing how to interface a load cell, so I did learn something useful

 

[apostolakisl]

Scientific scales are accurate to fractions of a gram.  They cost more, but for less than $100 you can get one accurate to .1 grams.

 

[TonyNo]

Maybe this?
 
http://www.omega.com/ppt/pptsc.asp?ref=LCL

 

[roussell]

You could also mount the box to the end of a lever to multiple the force applied to the load cell.
 
How about having the box suspended in a 'U' shaped column of water on one side of the 'U' and measure the displacement of water on the other side with a level sensor? If the items in the box can get wet, just drop them in an appropriately sized vessel of water and measure the displacement of each object being dropped in with some type of level sensor - it worked for Archimedes. ;-)
 
Terry

 

[maltesemanTS1]

yeah, scientific scale probably most practical solution...but there are force sensitive resistors with about the same footprint that you need and with huge dynamic ranges (http://www.digikey.com/product-detail/en/30-81794/1027-1001-ND/2476468)