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?
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.
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)
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.
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