Test and Measurement Forum

load cell

Which product is right for your exact requirements

load cell

Postby boris_lalyman@api-hk.com » Wed Jun 08, 2005 3:08 am

I'd like to be able to monitor load cell.

What is the best solution?
boris_lalyman@api-hk.com
 

Postby Sarah » Thu Jun 09, 2005 10:28 am

Hi

Thank you for your post.

The best solution depends on the output of the load cell. What output does it give?

Best Regards
Sarah
 

load cell

Postby boris_lalyman@api-hk.com » Sat Jul 23, 2005 4:42 am

I am actually quite ignorant for all this signal treatment.

I would be very gratefull if someone could explain to me how to aquire a load cell signal and what would be necessary as hardware to do so.

Best regards

Boris Lalyman
boris_lalyman@api-hk.com
 

Postby Sarah » Mon Jul 25, 2005 11:40 am

Hi

Thank you for your post.

The load cell will give you some kind of signal outut. This could be in V, mV or mA for example. It is important to know what type of output it gives to be able to interface it correctly. Once you know this then you can chose the unit best suited. This will be a unit that has a similar input range to the output the cell is giving, or one which you can easily connect a conditioned signal to.

If you can provide me with more information as to the output of the load cell then I will be able to advise you as to the best unit to use with it.

Best Regards
Sarah
 

load cell

Postby boris_lalyman@api-hk.com » Mon Jul 25, 2005 2:36 pm

Thank you for your prompt reply.

I suppose that the output is mV, because the sensibilty is rated 1.0 +- 0.01 mV/V.


Thanks in advance

best regards

Boris Lalyman[/img][/list][/i]
boris_lalyman@api-hk.com
 

Postby Sarah » Tue Jul 26, 2005 9:06 am

Hi

Thank you for your post and the extra information.

What is the maximum load of the cell and what is the maximum output? If it has a mV output the the TC-08 may be the best option, but I will need to know some more information to be sure.

Best Regards
Sarah
 

Postby larchard » Sat Jul 30, 2005 3:05 am

The 1mv/V specification means at full scale you'll get 1mV output for each V of excitation voltage you apply. What makes it more difficult is that the output is differential and superimposed on a DC offset of half the excitation voltage. If you put 10V in, you'd be looking for the difference between two signals of about 4.995 to 5.005V.

Have a look at rswww.com and look up part number
846-171
It provides stable excitation to the bridge, then amplifies and conditions the output to something that any Picoscope will be happy with.

Click on Technical Info from that page. The RS datasheet (you'll have to register to download it) for loadcells and strain gauges gives a fair introduction.

An alternative approach is to use an AtoD converter with built in conditioning such as an Analog Devices AD7714. That's what we're doing on our product - but that chip is a complex beast.
larchard
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