Results 1 to 8 of 8
  1. #1
    CyBer
    Guest

    Wiring LED question.

    Anyone know how to wire an LED? I'm just wanting to wire a single LED to a battery (hopefully a watch battery) for a project I'm making. I looked on the internet and found some tutorials, but it seems they all use a bigger battery. Can I use a watch battery? And if so, do I need a resistor?


    Thanks for any help.



  2. #2
    All-Star
    Points: 36,285, Level: 58
    Level completed: 70%, Points required for next Level: 365
    Overall activity: 0%
    Achievements:
    Veteran25000 Experience Points
    247cy's Avatar
    Join Date
    Nov 2006
    Location
    Spring Hill, KS
    Posts
    1,097
    Points
    36,285
    Level
    58
    Thumbs Up
    Received: 0
    Given: 0

    Re: Wiring LED question.

    Can you provide some specs on your LED and the voltage of the battery?



  3. #3
    CyBer
    Guest

    Re: Wiring LED question.

    No idea on either as I haven't even purchased them yet, any suggestions? It's going to go in a book cover and needs to be small.



  4. #4
    All-Star
    Points: 36,285, Level: 58
    Level completed: 70%, Points required for next Level: 365
    Overall activity: 0%
    Achievements:
    Veteran25000 Experience Points
    247cy's Avatar
    Join Date
    Nov 2006
    Location
    Spring Hill, KS
    Posts
    1,097
    Points
    36,285
    Level
    58
    Thumbs Up
    Received: 0
    Given: 0

    Re: Wiring LED question.

    Well, small can be a relative term. Are you wanting to solder wires on or get one that has leads (legs) on it?

    If you get a leaded one, the long leg is the anode and should be connected to + of the battery. The short one is the cathode and should be on the - side of the battery.

    I would recommend around a 3V battery, so yes a watch battery should light it.

    You don't need a resistor if you pick your battery and LED carefully, but the LED just won't last as long. The resistor in the circuit is there to protect the LED. LEDs are rated for a certain current, and will burn up quickly if you give them too much. Most common LEDs are rated around 2V (white & blue LEDs are often higher - 3 to 4 V).

    If you go with a 3V battery and get a 2V LED @ 20 mA, then the resistor you would need is around 50 ohms. It may be hard to find a 50 ohm resistor, and the value is small enough to not matter that much. You could buy a few extra LEDs and batteries to experiment and find out how long the LED lasts.

    This link has a formula for calculating the resistor value, along with some simple wiring diagrams. You should be able to get the specs for the LED if you buy some online or at radio shack, etc.


    Last edited by 247cy; 10-18-2011 at 09:40 AM.

  5. #5
    CyBer
    Guest

    Re: Wiring LED question.

    I'm going to wire the LED to a battery and a switch so I can turn it on and off, I'm going to get one with "legs" but solder on more wire on to it. I'm putting the light in a book that I am illustrating and it needs to have an on and off switch. It's a children's book about an ugly pumpkin (the pumpkin is going to light up)



  6. #6
    All-Star
    Points: 36,285, Level: 58
    Level completed: 70%, Points required for next Level: 365
    Overall activity: 0%
    Achievements:
    Veteran25000 Experience Points
    247cy's Avatar
    Join Date
    Nov 2006
    Location
    Spring Hill, KS
    Posts
    1,097
    Points
    36,285
    Level
    58
    Thumbs Up
    Received: 0
    Given: 0

    Re: Wiring LED question.

    Sounds like fun.

    You have some choices in LEDs. The most common are 5mm Round, they have leads which will make wiring a bit easier. They can be a bit bulky for your application however, so you might consider surface mount LEDs. They offer a smaller profile - fairly flat and rectangular. You'll have to solder to them though, and depending on the size you get, you may need a magnifying glass and tweezers to help.

    You can probably find all the parts you need at one of the online shops, mouser.com or digikey.com.

    Good luck.



  7. #7
    CyBer
    Guest

    Re: Wiring LED question.

    Thanks for the help, I figure if the story isn't good I'll at least have something interesting.



  8. #8
    Legend
    Points: 192,324, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 9.0%
    Achievements:
    Veteran50000 Experience Points
    jbhtexas's Avatar
    Join Date
    Oct 2006
    Location
    Arlington, TX
    Posts
    10,499
    Points
    192,324
    Level
    100
    Thumbs Up
    Received: 29
    Given: 23

    Re: Wiring LED question.

    Here's a little LED calculator site you can use if you don't want to do the calcs yourself.

    Current limiting Resistor calculator for leds


    "Don't worry Boss...they can't do nothin' 'til they're through sparklin'..."

    Avatar - America's new superhero...Cenex Guy

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
  • Football
  • Iowa State vs. North Dakota State
  • August 30, 2014
  • 06:00 PM