Supplying Voltage to Load Cells

[GHaulk]

Does anyone have an opinion on whether you should feed a load cell excitation voltage with a linear or switching power supply? I have an application where I am feeding a load cell with 10VDC excitation from a switching SOLA power supply and my raw weight signal has some variation. It seems to be at a constant frequency. Any suggestions?

 

[MacGyverS2000]

If your feed signal is dirty, the load cell signal is going to be dirty... GIGO.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[bogeyman]

A very high performance linear supply is normaly required.
You may have mains bourne interference causing your error voltage. Make sure that the signal and supply pairs are well twisted and if possible use an overall screen on the load cell cable.
To overcome AC mains interference an AC excitation scheme with phase sensitive detectors works well.

 

[OperaHouse]

Since the excitation supply usually floats, capacitive feed through can be a problem. Usually filtering is done on the read voltage or digital averaging. I sense you are reading this into a computer using a fas A to D converter. A .1 uf from each excitation power leg to ground would eliminate any capacitive feed through. Since this is fairly high frequency it would be easy to eliminate. I've measured pulsing transducers with running 64 averages and had nice stable readings.