Am I using a LM393 correctly?

Discussion in 'The Projects Forum' started by ryanschuermann, Nov 6, 2011.

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  1. ryanschuermann

    Thread Starter New Member

    Nov 6, 2011
    Hey all,

    I've searched the archives, read a lot of threads and -think- I know how to accomplish what I want to do. I would appreciate some tips and feedback to my proposed project as it seems to be slightly different from all the others.

    This is a 12v dc automotive application.

    My engine management system uses a completed ground path to signal a closed throttle body condition, and another completed ground path to signal wide open throttle, via triggered switches. I want to replace this system with a newer model throttle body that uses a position sensor (potentiometer). I could custom make a bunch of brackets to custom mount the switches to be triggered by the new throttle body, but space is limited and I'll eventually need to use the pot as an input when I upgrade management systems, so why not use it now...

    The pot has a +5v input, gnd, and signal output ranging from +0.5v (closed) to +4.5v (wide open) ..or somewhere near those values as my meter is really good but not $5,000 good.

    I want to trigger the completion of two ground paths, only at specific voltage output levels of a pot <= +0.5v and >= +4.5v... using a LM393 the correct IC?

    as I understand the schematics floating around, if I supply the dual voltage comparator with +12v (Vcc) from the car, GND, and then...

    if i supply comparator 1
    - with constant +0.5v,
    + with pot output
    ... when + is below 0.5v GND will be output 1

    if i supply comparator 2
    + with a constant +4.5v
    - with pot output
    ... when - is above +4.5v GND will be output 2

    most of the examples I've seen try to complete the output path when voltage is between 2 values, I want to complete the two paths, separately, when voltage is above and below respectively.

    Obviously I'll have to add some resistors and capacitors between the board's +12v supply and the +0.5v and +4.5v inputs to ensure constant input v to the comparators.

    I'm just worried, will the comparator handle a +0.5v level?

  2. bertus


    Apr 5, 2008

    I am closing this thread as it violates AAC policy and/or safety issues.

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