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Old 03-07-2007, 04:45 AM  
rowan
Too lazy to set a custom title
 
Join Date: Mar 2002
Location: Australia
Posts: 17,393
Quote:
Originally Posted by Tempest View Post
Still not exactly sure what you need. Why do you need 40 LEDs and do you simply want them all to be ON? Do they need to all be conected in series? or in parallel?

Here's what I remember.. LEDs are basically diodes and diodes usually require 0.7Vs and LEDs needed about 10 milliamps to turn on.
LEDs are diodes but they don't have the same forward voltage as say, a rectifier or silicon diode. A typical forward voltage for a basic opaque red LED is 1.8V, green is slightly higher at about 2.0V, and white goes higher still, up past 3.5V. That's why many LED torches use 3 x 1.5V cells, to avoid the need for circuitry to step up the voltage.
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