Completing a half bridge strain gage configuration

Sensors Force & Weight
1

Hello,

I am about to make an application using strain gages in wheatstone

configuration and I would like to ask about the modules

https://www.sparkfun.com/products/13261

https://www.sparkfun.com/products/13878

I am not using an already completed wheatstone bridge circuit (like load

cells) , but instead I am using 2 strain gages and I want to complete a

half bridge circuit configuration with these 2 gages.

My question is if any of your aforementioned modules has the ability to

complete the Wheatstone bridge ?

If yes, I will just need to wire the 2 strain gages.

If not, I will need to first find a circuit to complete the bridge and then wire the hole configuration to any of your modules. In this case is there such a bridge completion module available?

Thanks for the help,

2

Hi Giannis.

It’s actually super easy and you don’t need a combinator board at all. If you have two sensors, just connect them like the diagram below and you’re good to go!

Capture.JPG

3

Hello TS-Chris,

Thanks for the immediate response. I think your image refers to the case when load cells are used, and not strain gages which is my case. The configuration I want to make is in the image below. So I have to solder the gages in a circuit with two resistors, aren’t I ? Correct me if I 'm wrong.

Wheatstone-half-bridge-circuit.png
Best regards,

Giannis

4

Hi Giannis.

Sorry about that, I thought you were referring to our [50kg Load Sensor that has a strain gauge and a resistor inside.

We don’t have a specific board or device to connect two individual stain gauges into a Wheatstone bridge, but a bit of proto board, two resistors and the leads from your strain gauges would work. Something like [PRT-12702 or [PRT-08808 is what I’d use.

Your resistors should be the same resistance as the strain gauges you’re using.](ProtoBoard - Square 1" Single Sided - PRT-08808 - SparkFun Electronics)](SparkFun Solder-able Breadboard - Mini - PRT-12702 - SparkFun Electronics)](https://www.sparkfun.com/products/10245)

5

Thank you.

I have been thinking of soldering the bridge completion circuit on my own but the problem is that I could not find resistor of 350 Ohm, which is the resistance of the strain gauges used.

Best regards,

Dadiotis Ioannis

6

You could always add several values of resistors together to get your desired value. For instance, a 330 ohm and a 20 ohm resistor connected in series will give you 350 ohms.