Hal Effect Sensor to 0-5v output Needed

Discussion in 'The Projects Forum' started by howiroll, Jun 21, 2016.

  1. howiroll

    Thread Starter New Member

    Jun 21, 2016
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    I am working on a project for a pulling tractor with a diesel engine (No electronic coils or spark plugs, just a 12v battery to start it and that is it).

    I would like to use a hall effect sensor to pick up a signal from the rotation of the crank and then use that for RPMs. The problem I am having is that the hall effect sensor just outputs a pulse signal and the data logger needs a 0-5v signal.

    So basically I need something that will convert a 0-83HZ (5000 RPM) signal to 0-5v so that I can record RPM on the datalogger.

    Any help would be greatly appreciated!
     
  2. bertus

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    Apr 5, 2008
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  3. howiroll

    Thread Starter New Member

    Jun 21, 2016
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    Thanks for that link, definitely looks like a good sensor to use! It looks like I will still have the same issue, the data logger can only have a 0-5v signal input that has to be scaled with some value. So in the logger I need to scale it to say 0v to 5v is 0rpm to 5000rpm (or whatever it needs to be scaled too).

    Right now we have a lot of pressure sensors, so those are easy, you can just buy them already scaled with a 0-5v output. 0v is 0psi, 5v is 100psi. Put since this is a pulse signal, and I need a 0-5v signal, it has caused some issues.
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    That would not be a problem.
    Have a look at this drawing I made:

    Hall_sensor_to_datalogger.png

    Bertus
     
  5. Dodgydave

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    Jun 22, 2012
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  6. howiroll

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    Jun 21, 2016
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    Thank you so much for that! Can you explain to me what an open collector output is so I can better understand what is actually happening here with the resistor added?
     
  7. Dodgydave

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    Jun 22, 2012
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    open collector, means there is no supply to the positive rail, so if you require a pos/neg signal a resistor has to be connected to pull it up.
     
  8. bertus

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    Hello,

    You could see the NPN open collector as a switch.
    There is no voltage coming from the switch.
    The resistor will put a voltage on this switch.
    When the switch is open, the output will be 5 Volts.
    When the switch is closed, the output will be about 0 Volts.

    Bertus
     
  9. howiroll

    Thread Starter New Member

    Jun 21, 2016
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    Will adding the resister help me in creating a somewhat linear scale from ~0v to 5v?

    For example:

    theoretical 0v would be 0rpm
    2.5v would be 2500rpm
    5v would be 5000rpm

    Inside the logger, I have to scale it give it data points like the above example so that it then knows what the values in between are. The logger has no counter or timer. It just sees 0 to 5v signals that I can then scale to whatever values I want them to read on the gauges.
     
  10. Dodgydave

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    Jun 22, 2012
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  11. howiroll

    Thread Starter New Member

    Jun 21, 2016
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    Ok, thank you very much for the information. It seems like it would be an "off the shelf" item that people would have but its been more difficult to find that I thought.
     
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