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Help with circuit?

  1. Dec 4, 2012 #1
    Hello, I need help with this circuit. I didn't post this in the homework section because it isn't homework I'm just doing this for fun.
    circuit:
    http://imgur.com/i5fSX [Broken]
    image isn't working so here's a direct link: http://imgur.com/i5fSX [Broken]

    It is a 5 V input and three 100 OHM resistors in series and one LED. I can't measure current through it because fuse on multimeter died. I'm sure that 5 v is coming in because I tested that and the resistors are 100 +- 5 ohms I tested that too.
    I have these leds (http://www.radioshack.com/product/index.jsp?productId=2062588) from radio shack and people on the website say that I need around 300 ohms at 5 volts to run turn them on but nothing.

    I hope you guys could help out a circuit noob
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Dec 4, 2012 #2
    You know you have 100Ω resistors, measure the voltage across the resistor, then calculate using:

    [tex] I=\frac V R[/tex]
     
  4. Dec 4, 2012 #3
    Weird, I'm getting zero voltage across the resistor
     
  5. Dec 4, 2012 #4
    It looks like you are off by one hole in a couple of places. Rows of holes are connected, columns are not.
     
  6. Dec 4, 2012 #5
    Thanks a lot man. Yea this breadboard is different from the one we use in class. I was looking at everything else but it was just this simple fix.
    after I measured the voltage now I'm getting 0.1667 like expected :)

    thanks all for input
     
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