Voltage is Lowered While Testing a Circuit

Updated Feb 12, 2018

Reported In

Hardware

  • myDAQ Student Kit

Issue Details

  • My hardware is outputting a lower voltage than I tell it to.
  • Using the DMM, I tested the voltage of a series circuit powered by the analog output of a myDAQ, and it read the proper value.  However, when testing a parallel circuit, the DMM read an lowered value.

Solution

If the resistance of a circuit is too low, a device will not be able to output the correct voltage, as it would draw more current than the source can provide.  Check the specifications device of your supply sheet to make sure the current drawn is within specifications.

Additional Information

Ohm's Law states that voltage is equal to current times resistance, or V=I*R.  By multiplying the maximum current output by the total resistance of your circuit or load, you can therefore calculate the highest voltage that the supply could reliably output.

Trying to output an out of spec current will therefore cause unexpected voltages to be outputted, as the device cannot handle the request you are giving it.  

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