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LED not working plz help! — Parallax Forums

LED not working plz help!

biospikesbiospikes Posts: 3
edited 2009-05-22 23:54 in Robotics
hey guys.
im trying to get this LED to work but its not i think i just need a different resistor

heres a link to the specs of the LED and resistor
http://i214.photobucket.com/albums/cc297/puzzlesasuke/IMG_3128.jpg

any help would be really appreciated

im new to this forum so idk where i should post this, so sorry if this is the wrong place

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-05-22 23:02
    A different resistor won't help. Notice that the forward voltage is 5-6V. That's more than any normal microcontroller can provide without some kind of external switch. You need to provide more information about what you're trying to do. Are you trying to switch this LED using a Stamp? How is this all powered?

    Your question is not about robotics. A better place would be The Sandbox. If you're trying to use this LED with a Stamp, then the Stamp forum is appropriate, etc.
  • biospikesbiospikes Posts: 3
    edited 2009-05-22 23:13
    im trying to put it in my xbox controller to make the button's light up, so it'll get its power from the xbox idk how much power that is but right now ive testing the brightness and making sure they work with a battery pack that uses 4 AA's i got the other 3 LEDs to work so far i just need this last one to complete it,

    the end project will look like this
    http://i214.photobucket.com/albums/cc297/puzzlesasuke/End_Product.jpg

    oh okay ill keep that in mind next time im going to post thanks
  • Mike GreenMike Green Posts: 23,101
    edited 2009-05-22 23:33
    If you just want to continuously run this LED off a 5V supply, try a 51 Ohm resistor. This will give a 1.1V drop at 20mA. Since you have some 150 Ohm resistors, you could just connect 3 of them in parallel to get 50 Ohms. You could also use 2 - 100 Ohm resistors in parallel to get 50 Ohms.

    If you want to run this LED off a 6V battery, try a 100 Ohm resistor for a 2V drop at 20mA. From one link you provided, it looks like the measured forward voltage is about 3.8V at 20mA and I'm basing the resistor values on that.

    If you want to switch the LED on and off using a microcontroller, try a 47 Ohm resistor in series with the LED with the anode of the LED connected to the resistor and the other end of the resistor to a Stamp I/O pin. The cathode of the LED should be connected to ground (Vss).
  • biospikesbiospikes Posts: 3
    edited 2009-05-22 23:54
    ok thanks ill try it out when i get a chance
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