output voltage drop in USB-6212

[Jonnas]

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@LindsW wrote:

Hi Jonnas,

It sounds like a unity gain op-amp (voltage follower) is the correct approach.  Take a look at this white paper article, which discusses how to hook up a DAQ device with a voltage follower (section 3) to double check you have it connected correctly:

http://www.ni.com/white-paper/4494/en/#toc3

Regards,

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Thanks Linds!

AS a matter of fact, I did go the the op-amp road but it turned out that the 

follower op-amp indeed follows the voltage drop... 

I figured that the real problem I have is the 2mA limit on the USB-6212

So I designed the simplest emitter follower transistor current amplifier [examle in the link]

(http://www.colorado.edu/physics/phys3330/PDF/Experiment7.pdf)

and for now it works perfectly.

I'm happy

Thanks for a nice discussion!

-J