Load Cell (i am not getting it)

General
1

I purchased a
https://www.sparkfun.com/products/10245 Load cell and it has
3 Wires
All the tutorial on the internet shows load cells with 4 wires .

I am not understanding how can i use it ! do i need amplifier ?
If anyone can help please tell me what to buy more so can make a scale out of the spark core (it doesnt have to be that accuate) 20g less or minus is no problem.

Note : I have used FSR they are not accurate at all and the pressure must be above them not like a load cell where the load can be somewhere else (thats how i understand it )

Question: Will a flexiForce be accurate ? better than the normal force sensor . can i use it to scale ?

Thank you,
Maroun

2

Hmm, Iā€™m less familiar with the electronics myself, but it looks like people tend to use an amp ( something like this? - https://www.sparkfun.com/products/9816 ). I also found an instructables here that talks about using a load cell here - http://www.instructables.com/id/Arduino-Load-Cell-Scale/

I hope that helps!

Thanks!
David

1 Like
3

You typically do need an amplifier to get the output signal into a usable area (the output is only a few millivolts, while the spark needs a signal up to 3v).

A 4-wire gauge is a full-Wheatstone bridge - it uses 2 strain gauges back to back which provide some form of internal compensation for temperature. This 3 wire one is a half-wheatstone. In the comments, they talk of putting 5v across black and red, or black and white, an reading the signal from the 3rd wire. (Seems black/red for power, and white for signal would make most sense, but probably best to mail sparkfun for clarification.)