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Homework Help: Transducer terminology question

  1. Apr 6, 2005 #1
    If you have a rotary potentiometer that measures the amount of angular displacement, what would you say the output signal of the transducer is? I'm unsure if it's resistance or voltage. A change in angular displacement changes the point of contact within the potentiometer, which directly affects its resistance. However, in our case, we are measuring the change in voltage over the potentiometer with a DMM. Actually, there is a list of parameters we need to figure out, and this is what I've come up with.

    Input Signal to Transducer: angular displacement
    Output Signal from Transducer: voltage
    Output device: DMM
    Output of the sensing system: resistance

    I'm mainly just confused with the many different types of output. I would think the transducer is the "big picture" (of which our important quantity is voltage), while the sensing system is the potentiometer itself, which changes its resistance. Then I just figured that the output device is whatever your measuring the change with.
  2. jcsd
  3. Apr 6, 2005 #2


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    Science Advisor

    You're pretty much correct. Even though the pot. is a variable resistor, you power it so that you get a variable voltage as the actual output signal. The voltage has a lot of benefits, especially if you have to carry that signal over a distance or if you don't have resistance measuring devices.

    The two transducer outputs you'll see the most of are voltage and current outputs. The standard current output is a 4-20 mA signal. There are others such as a frequency outputs.

    To answer your original question, the output signal is a voltage signal. The signal you actually measure is what that refers to, not the physical "thing" you are measuring, like angular displacement.
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