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Water pump controlled by sensor???

Discussion in 'Sensors and Actuators' started by bmxerds, Feb 12, 2013.

  1. bmxerds

    bmxerds

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    Feb 12, 2013
    Hello I need help finding a circuit where a 0-5v pressure sensor controlls a 12v water pump. As the pressure increases on the sensor the out put of the sensor rises from 0v to a maximum of 5v.I need the sensor to control the 12v water pump in a pwm fashion. Also I need to be able to adjust the pumps start up. Also I want this to be a circuit I can solder up. I don't want to program anything with digital ICs. Thanks
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Is zero volts 0% or 100%?
     
  3. bmxerds

    bmxerds

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    Feb 12, 2013
    It is 0%
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The simple answer is to have a (triangular or sawtooth) that varies from 0V to 5V at the frequency required for your PWM.

    This is compared to your input voltage by a comparator. The output is your PWM signal.
     
  5. bmxerds

    bmxerds

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    0
    Feb 12, 2013
    I dont need the pump to just turn on. I need it to slowly increase in speed linearly in reference the the input voltage.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,192
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    Jan 21, 2010
    Hence your request for PWM and my response which details how to do it.

    Here it is graphically:

    [​IMG]

    The red sawtooth is at the frequency of the PWM.

    The green and blue lines on the first graph are an example low and high voltage.

    The next two graphs are the output of a comparator which compares the sawtooth (red) signal with the control voltage.
     

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    Last edited: Feb 13, 2013
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