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Homework Help: Help with 3 input AND gate

  1. Apr 3, 2008 #1
    Okay, so Im trying to use the breadboard and I have a hard time with a three input AND gate. Guess I can do a schematic

    http://imageiso.com/out.php/i17298_3inputandgate.JPG [Broken]

    So in my bread board, I have pins 1 and 2 as inputs..with pin 3 as a LED (output), and I have a jumper connecting pins 3 and 4 cause the result of the first and gate determines if the second AND Gates lights the LED..and I have pin 5 as the input..and pin 6 in another LED..now I connected pin 7 to the ground and pin 14 to +5V..this is the problem: the first and gate works..first LED (on pin3) lights up, but the second one doesnt

    I tested everything and I reconnected it to my breadboard..sorry I dont have a picture of it so Im curious why the second one wont light up..Any ideas guys?
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Apr 3, 2008 #2

    chroot

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    So... do you have pins 1, 2, and 5 all tied high?

    - Warren
     
  4. Apr 3, 2008 #3
    yes i did that..its all on high..like on the +ve line..where pin 14 is connect to +5..and i have another wire connected to the power source..well the first led works

    and I tried another LED..so I really dont know what Im doing wrong
     
  5. Apr 3, 2008 #4

    chroot

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    How exactly have you connected pin 3 to both an LED and to pin 4?

    - Warren
     
  6. Apr 5, 2008 #5
    nvm i fixed it.apparantly i think i broke the circuit when i added an extra input to pin 4..i just removed that wire and it worked..
     
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