Author Topic: Determine wheatstone bridge pinout  (Read 1971 times)

0 Members and 1 Guest are viewing this topic.

Offline Rachie5272Topic starter

  • Regular Contributor
  • *
  • Posts: 176
Determine wheatstone bridge pinout
« on: August 09, 2015, 12:43:53 am »
I have a load cell I'm using for a project, but I'm not sure how to connect it.  I'm sure it's a wheatstone bridge, but how do I determine which pins are which?  In theory, the resistance between any two nodes in a bridge will be identical.  Is there a simple method for finding opposite nodes?

Here's the datasheet, for all the good it will do:
http://www.omega.com/Pressure/pdf/LCDB.pdf
 

Offline rs20

  • Super Contributor
  • ***
  • Posts: 2322
  • Country: au
Re: Determine wheatstone bridge pinout
« Reply #1 on: August 09, 2015, 12:49:18 am »
Your assumption isn't quite right -- the resistance between two opposite nodes will be equal to R (where R is the resistance of any one element in the bridge), but the resistance between two adjacent nodes will be 0.75R.

Once you've found two opposite nodes that way, it doesn't really matter how you connect it up -- I believe you can connect a wheatstone bridge reflected upside down, side-to-side, and the worst that'll happen is positive loads will be reported as negatives. Which you can fix by reversing any two wires, or just adding a "-" in software  :)
 

Offline retrolefty

  • Super Contributor
  • ***
  • Posts: 1648
  • Country: us
  • measurement changes behavior
Re: Determine wheatstone bridge pinout
« Reply #2 on: August 09, 2015, 01:04:05 am »
As told by rs20 an ohm meter will determine node arrangement. That aside Omega generally uses red (+) and black (-) wires as the excitation node, and green (+) and white (-) for the measurement node.

 

Offline Rachie5272Topic starter

  • Regular Contributor
  • *
  • Posts: 176
Re: Determine wheatstone bridge pinout
« Reply #3 on: August 09, 2015, 01:15:24 am »
Ah, right you are.  Never try to do resistor math while tired...
 

Offline jtroyase7

  • Newbie
  • Posts: 2
  • Country: de
Re: Determine wheatstone bridge pinout
« Reply #4 on: January 07, 2020, 01:18:59 pm »
Hello,

I have a similar problem and was wondering if you could help me.
I want to use a Xtrans CODAN pressure transducer that I know it works with a wheatstone bridge configuration. As expected it has 4 pins (GND, Vsupply, Vright, Vleft), however I am not able to find any datasheet that can indicate me which pin corresponds to which type of signal and the company does not want to help me. I am a little bit new to electrical engineering and do not understand properly your explanations. However, I have measured resistance across the pins (please see attached image).
I would like to know which letter (A,B,C,D) corresponds to which number (1,2,3,4).

Thank you very much,
 

Offline andy3055

  • Super Contributor
  • ***
  • Posts: 1159
  • Country: us
Re: Determine wheatstone bridge pinout
« Reply #5 on: January 07, 2020, 06:02:22 pm »
Long time since I studied these. Here is a useful site:

https://www.electronicshub.org/wheatstone-bridge/
 

Online Kleinstein

  • Super Contributor
  • ***
  • Posts: 15155
  • Country: de
Re: Determine wheatstone bridge pinout
« Reply #6 on: January 07, 2020, 06:25:12 pm »
Those resistor values are not compatible with the simple 4 resistor bridge circuit. So there must be something else inside.
 

Offline jtroyase7

  • Newbie
  • Posts: 2
  • Country: de
Re: Determine wheatstone bridge pinout
« Reply #7 on: January 08, 2020, 05:50:00 pm »
Thank you for you answers. I will keep pushing the company to obtain the information (seems like the only thing I can do) and I will post it here their answer so another person could benefy if he/she gets in the same situation as me.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf