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Load cell amplifer signals

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Hi All, 

 

I'm trying to build an app to read a signal from a RS load cell & amplifier using a USB6210 daq card. I'v tried SE & Diff connections, and I see a change in signal when I apply a load, however it's not quite what I expected (see attached screenshots from MAX).

 

I'm supplying an external 5V to the amplifer, so with no load expect to see approx 3V from the amp - this works OK. With a load applied I expected to see a constant voltage drop, however I seem to be getting an unstable, spiked drop in voltage.

 

Any ideas why this is happening, any help would be much appreciated.

 

Thanks,

 

Martin 

 

 

Link to RS load cell & amp spec sheet: 

 

http://docs-europe.origin.electrocomponents.com/webdocs/0099/0900766b80099349.pdf 

 

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Solution
Accepted by topic author Martin.Griffiths

Looks like a 100Hz hum ..... grounding and shielding and a clean powersupply for your amp??

Any switched power devices (powersupplies, converter, ....) nearby (shure your PC 😉 ?? Electronic ballasts for modern energy saving light or dimmer ?? 

 

 

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


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Thanks Henrik, using shielded cable solved the noise problem. I also changed the supply to the amp to give 12V instead of 5V, it seemed 5V was just below the operating range of the amp.

 

Thanks again.

 

Martin  

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Waoooo good source of information for me.. Your progect was perfect indeed.

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