I'm looking for either an electronic kit for building a weight scale, or a site with resources on how they work(to take a cheap one apart). Does anyone have experience with these? Or can one of you help point me in the right direction?
Most use a wheatstone bridge circuit, to measure the strain of a strain gauge (this is why most scales do not move at all). Here is a page that explains it plus the math http://www.eetimes.com/design/analo...ansducer-in-a-Wheatstone-bridge-configuration The AD1651 op amp even has a circuit diagram to use a strain gauge too. Using the output to display something useful is probably beyond the scope of this forum and you would be better off asking an electronics forum, the Arduino microcontroller has electronic scale circuits so you could ask around there too.
