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Getting Feedback on Flow Sensor

Discussion in 'Sensors and Actuators' started by Ryan S, Oct 21, 2017.

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  1. Ryan S

    Ryan S

    Oct 21, 2017
    I'm trying to use a flow sensor to get PWM feedback to be received by a microcontroller. To test the sensor, I've wired the following to get feedback on an oscilloscope so I can get a feel for how the frequency adjusts based on the flow rate.
    Koolance SEN-FM18T10 Hookup.png

    When I wire the flow sensor (the other grey sphere is a temperature which I haven't started on yet), the oscilloscope does not change voltage or frequency (solid line at 7V) when I have water flow through it. I've adjusted this circuit so that the resistor is in different places (I'm new to this thing so I figured I was doing something wrong) but at this point I'm not sure what I'm doing wrong. Is there some glaring problem I've overlooked or is this part just possibly broken?
  2. Alec_t


    Jul 7, 2015
    Welcome to EP!
    You don't have a ground connection going anywhere useful.
    What is the flow sensor spec? Datasheet?
    shrtrnd likes this.
  3. Minder


    Apr 24, 2015
    The link to the sensor does not show any electrical specs?
  4. kellys_eye


    Jun 25, 2010
    Suggest one lead of the flow meter goes to ground, the other (signal) lead goes to 12V via a resistor and you take the measurement signal from the resistor leg connected to the transducer.

    It's only a two-wire sensor and one must be ground. The only other way to get power and a signal is via a 'load' (the resistor) connected to the supply line.

    Note - mis-connection MAY have irreparably damaged the sender.....
  5. Ryan S

    Ryan S

    Oct 21, 2017
    You are amazing! A replacement part finally came in and I was able to get it working off of your recommendation!!!

    Was definitely a difficult challenge given that the company didn't provide any datasheets and weren't willing to help me figure this out... thanks to all that helped out
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