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light up an LED with a battery

what to do for reducing ampere?
i want to light up a LED which need only 25ma but every batt. is over this amp. so i have to reduce the amp.


Sun, 26 Aug 2007 11:55:52 +0000

It's not really reducing the ampere, but rather, limit the current. LED's have low internal resistance, so they will burn out prematurely if the current isn't limited. You can limit the current by wiring a resister in series with the LED.

To determine the resistance needed, use the basic formula:

R = -

Substitute the forward voltage of the LED for V. Substitute the forward current of the LED for I. The result is the resistance in ohms.

Chieh Cheng
Sun, 26 Aug 2007 21:31:58 +0000

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Title: Battery Capacity Conversion
Weblog: Camera Hacker
Tracked: Sun, 26 Aug 2007 19:37:41 +0000

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