Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Measuring Force?

  1. Jul 10, 2005 #1
    I need to measure force and input the data into a computer. I found some force sensitive resistors, but they weren't capable of handling forces of several pounds. What I wish to build (if cheap enough) is something like this:

    Anyone know what is needed to build one, where do buy one that's cheaper, or is that the best I am going to be able to do?
  2. jcsd
  3. Jul 11, 2005 #2


    User Avatar
    Science Advisor

    You're not going to find much cheaper than that. Most load gauges are strain gauge based. When you add in the electronics for that portion, plus the electronics for the output you're starting to get a bit higher cost. What are you willing to spend? There are some scales and hand held force transducers that output on a serial line. What exactly are you doing with it would be helpful to know.
  4. Jul 11, 2005 #3


    User Avatar

    Staff: Mentor

    How about using a spring and a linear potentiometer? Choose the spring so that it stays linear for the forces that you want to measure (F=kx), and monitor the resistance of the wiper of the pot. You could even do a cheap RC thing if you don't have an easy way to read the resistance. Add a capacitor and drive an edge into the potentiometer+cap from the TX line of the serial port on your PC. Monitor how long it takes for the RX line to respond to the edge going through the RC lowpass circuit. You can probably calibrate the whole setup to be accurate to within a few percent...

    If you have a simple analog I/O card in your PC, you could just measure the resistance or form a voltage divider to tell you the wiper position. Let us know what you come up with! -Mike-
  5. Jul 11, 2005 #4


    User Avatar
    Science Advisor
    Gold Member

    How about buying a cheap digital bathroom scale and interface to its' electronics?

  6. Jul 11, 2005 #5


    User Avatar
    Science Advisor
    Gold Member

    If your computer has a sound card you can input data with this oscilloscope program.
  7. Feb 11, 2008 #6
    Can you use a torsion spring with a potentiometer to measure the force.d
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Measuring Force?
  1. Measuring current (Replies: 5)

  2. Distance measurement (Replies: 2)