USB-analog output ground isolation

[Tony S.]

Hi,

Does any USB based DAQ analog output deck has a isolated ground mode? 

I have a circuit as below, in which the working voltage(15V-1V) can be controlled by USB-6008 DAQ analog output(0-5V). It works well in my laptop since laptop has a isolated ground, thus the DAQ works like a differential voltage supply. However, it could not work at desktop because DAQ share the common ground as the motor. I wonder whether there is any DAQ device providing the differential analog output (I know USB-6008 can not)? Or can any one help to give any idea in designing the circuit use USB-6008.

Thanks for your kindly help.

Best wishes for everyone.

Tony

[Henrik_Volkers]

Here is one approach from OP Amps for Everyone

Make all R 10k and since you need 1-15V  the 15V single supply with a R2R output OP should fit.

It's not a diffential output, it's a diff in for your (ground refferenced) sink 😉

If that doesn't fit, take a look at full differential OPs.

[Henrik_Volkers]

Handbook of OP amp applications

Edit timed out 😉

This Appnote seems to fit best ....

Texas Instruments, Differential Op Amp Single-Supply Design Techniques, SLOA072,

[Tony S.]

It is really helpful. My problem is solved by your method.

Thank you very much.

Regards,

Tony

^_^