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Step 2: Test the LED

Test your LED to determine color, brightness and functionality. Pinch the LED legs, or leads, to the battery terminals. The longer LED lead, called the anode, should be touching the positive terminal (+) of the battery and the shorter LED lead, called the cathode, should be touching the negative terminal (-) of the battery.

Note that the positive terminal on the battery has a larger contact surface than the negative terminal. The positive terminal extends around the sides of the battery. Don't let the cathode lead of the LED accidentally touch the positive terminal of the battery. This will create a short and cause the LED to function improperly.

For more information on LEDs click here.
For more information on batteries click here.
 
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"Note that the positive terminal on the battery has a larger contact surface than the negative terminal. The positive terminal extends around the sides of the battery. Don't let the cathode lead of the LED accidentally touch the positive terminal of the battery. This will create a short and cause the LED to function improperly."

Is this particularly common? I'm hoping to let people choose their own colors for an LED project, so I'm not intending to attach all LEDs to a battery in advance of the project.
If you know any good tricks to avoid letting the cathode lead from contacting the positive side of the battery, what are they?
coat the battery with silicone or tape to only expose the actual front and back sides and not the wrap-around edge.
Linkster9992 years ago
i think u have ur info wrong Cathode is positive and Anode is negative
No cathode is definitely negative and anode is positive.
WearJDV2 years ago
As I read this ... I am trying to think of something really cool to do with these ...
k247br3 years ago
i think that is true.maybe you should think about it.
if it were entirely based on current limitation and not voltage, wouldn't hooking a 12V LED up to a car battery which is capable of pushing 300 CCA require a massive amount of resistance, compared to, say, hooking one up to 4 CR2303 batteries in series?

this is you web site :http://www.magical-led.com
gammaraptor4 years ago
Well, all my LED's are rated for around 2.2V. This sucks because i can't use just one 1.5v battery. I can't use 2 either, because it melts the chip. Anyways, what you need to do is to find a resistor....
intellijel5 years ago
Why are no current limiting resistors used? Does the CR2303 already have built in current limiting?
The only time you need current limiting is if the maximum voltage drop across the LED is less than the forward voltage of the battery. In this case, the CR2303 is 3.0V forward, and most of the LEDs are 3.0V rated, with 3.6V max.
If you put in a resistor, would it make the battery last longer? (with a dimmer LED) Or would it waste power as heat dissipated through the resistor?
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