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Voltage measurement on multiple channels: Problem with stuttering and strange influence on signal source.

Question asked by sauer on Sep 8, 2020

Hello everyone, I have a little problem here. Maybe you can help me with this.

 

I use an Arduino Uno board and two digital analog converters (DAC) to create two voltage signals 0-5V.
If I measure the voltages with a cheap multimeter everything is correct.

 

If I measure the two signals with my 34970A Data Acquisition + 34901A 20 Channel Multiplexer the following happens:

 

-If I measure only one voltage signal from the DAC everything is allright.
-If I measure both voltage signals from the DACs or one voltage signal from the DACS + other additional voltage signals then the multiplexer switching stutters and the voltage signals of the DACs are jumping around like crazy.

 

The high pins of the measurment channels are connecteted to the Voltage output of the DACs, the low pins to the ground of the arduino.
Somehow the measurment of multiple channels or the switching between the channels influences my arduino setup. But I have no idea how. Do you have any suggestions.

 

Best Regards
CS

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