Comparator LED circuit

Discussion in 'Homework Help' started by frisbee4all, Oct 26, 2009.

  1. frisbee4all

    Thread Starter Member

    Feb 22, 2009
    13
    0
    Question: Using an open-collector output comparator, draw a circuit that could be used to turn on an LED when an input voltage exceeds 5V.

    So far I just have a capacitor in series with a reverse-biased LED...I'm just not sure which direction the LED is supposed to be in.

    Thats all the information they give you in the Question, and there are no additional images. I'm not sure if they want the values for each circuit element but I'm pretty sure they do. I just don't know where to start for the calculations. Any help?
     
  2. Thav

    Member

    Oct 13, 2009
    82
    0
    I'm not sure why you would have a capacitor in series with an LED. Where is your comparator? It will help if you draw a schematic so we can help guide you rather than just give you the answer.
     
  3. frisbee4all

    Thread Starter Member

    Feb 22, 2009
    13
    0
    I'm just rewriting the question as it is given. There are no example images in the book. All the question says is what I typed in above. So I'm assuming its just two voltage sources, one connected to the + terminal and the other to the - terminal of an ideal op-amp with a voltage out terminal...
     
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