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U12 AO Offset Voltage


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#1 ktk

ktk
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Posted 15 February 2013 - 08:08 AM

I want to use the output of my U12 to control an external current source. It is a standard voltage controlled current source (VCCS) that outputs a current proportional to the input voltage. I control my U12 with Labview, and when I set the AO (either 1 or 2) to 0.00 V, I get 4 mV output from either AO0 or AO1 (measured against the ground on the Labjack itself). This leads to an unwanted DC current at the zero setpoint. I can remedy this on the VCCS, but would rather remove this offset from the AO itself. Is there any way to remove this DC offset?

#2 LabJack Support

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Posted 15 February 2013 - 10:39 AM

The issue is that the op-amp driving the analog outputs is powered from +5V and GND. That means the output you can get from the analog outputs can never go quite all the way to 0.0 volts or quite all the way to +5V. In a situation where you must go all the way to 0.0 or even below, the best option is to use an LJTick-DAC with a U3, U6, or UE9.


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