Author Topic: Wireless Loadcell  (Read 515 times)

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Offline ben23fTopic starter

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Wireless Loadcell
« on: June 03, 2013, 06:10:02 PM »
Hi All,

I am working on a project where i need to convert a regular loadcell to a wireless one.
I have a little experience with Xbee and Arduino but thats about it.
The loadcell is a strain gauge type that inputs 5V and output 0-5mV depending on the weight applied.
The issue is that the loadcell has a positive and negative signal output which i need to send as the receiver end needs both signal positive and signal negative as an input.
Also the transmitter attached to the loadcell needs to be no bigger than 60mm diameter by 100mm long.
Any help would be greatly appreciated.

Ben

Offline jwatte

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Re: Wireless Loadcell
« Reply #1 on: June 04, 2013, 10:23:29 AM »
Build a small PCB with an opamp to convert differential output to voltage. Sample using an ADC -- either Xbee, or using a small MCU like an ATTiny. Send the data using the Xbee. On the other end, use a digital potentiometer or similar between two power rails to generate the differential voltage again.

Offline ben23fTopic starter

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Re: Wireless Loadcell
« Reply #2 on: June 05, 2013, 05:09:49 PM »
I have made an op amp circuit that amplifies the loadcell output and converts it to a single wire with 3.5-4.2V range.
I worte a small Arduino sketch to print out the analog signal from the op amp and connected an Xbee to the arduino using an Xbee shield.
When i send the voltage via Xbee to a computer and vary the load on the loadcell, the analog value on the computer doesnt change.
Is their an issue with the change in voltage being too small?

Ben

Offline jwatte

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Re: Wireless Loadcell
« Reply #3 on: June 06, 2013, 12:30:19 PM »
That would depend on the specifications of the specific components and circuits involved.
You probably should go read the data sheets for more details.

 


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