Can I Use an Attenuation Probe with NI DAQ Devices?

Updated Aug 23, 2018

Issue Details

  • When using an attenuation probe with my NI multifunction Data Acquisition device, the signal is not being read as expected (ie. DC signal is saturated, or the signal is damped). However, the signal is read as expected when using other devices and the same attenuation probe. Are NI multifuction DAQ devices not compatible with attenuation probes?
  • I am looking for a high voltage probe to use with NI CompactDAQ (cDAQ), can I use an attenuation probe?

Solution

National Instruments DAQ devices have too high of an input impedance and input capacitance to work well with attenuation probes. 

Attenuation probes have a high output impedance. Therefore the high input capacitance NI DAQ devices act as low pass filters on the input voltage resulting in unexpected signals in many cases. 

This is not a problem when the gain of a probe is equal to one. However for attenuation probes (commonly 10x gain) this issue begins to appear. Scopes are designed to have a specific amount of input capacitance to work well with these types of attenuation probes. However, make sure to check that your oscilloscope or digitizer is compatible with the probe you choose. See Table 4 in the Oscilloscopes Product Flyer to confirm this.

Additional Information

Often times, a digitizer or oscilloscope can be a better choice for these applications. See Select the Right Oscilloscope Probe for Your Application.

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