I am trying to take a current measurement, run it into a PCB that splits the signal, and then output the signal in two places. One of the destinations is a RIO being used for feedback control, the other is a higher sample rate data logger.

When splitting the signal from the RIO into an oscilloscope there was a lot of added noise on the signal. This has me concerned that the data logger will see the same messy signal instead of the actual current.

What is the best practice method to take a single analog input to a PCB and use it to provide two separate outputs, without the two outputs introducing noise to one another?

  • 1
    \$\begingroup\$ Schematic? What is an RIO? \$\endgroup\$
    – Transistor
    Commented Nov 13, 2018 at 18:03
  • \$\begingroup\$ @Transistor Programmable I/O. Specifically the CompactRIO from NI \$\endgroup\$
    – MaxwellEE
    Commented Nov 13, 2018 at 18:08
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    \$\begingroup\$ A schematic would help. How are you taking the current measurement? What sort of noise were you seeing? How was the oscilloscope connected? \$\endgroup\$
    – ajb
    Commented Nov 13, 2018 at 19:26

1 Answer 1


This sometimes happens because of the sample and hold section in the input of data acquisition system. You can try op-amp as a buffer for the input signal.


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ It is better to use isolation amplifier, for an acquisition system. RIO works with 220V, that may generate ground loops. \$\endgroup\$
    – M KS
    Commented Nov 13, 2018 at 20:07

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