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LED Voltage question

I'm building a very simple lighting circuit involving a red LED. The specs give a typical Vf of 2.2V and a Vmax of 2.6V. If I use two NiMH cells to power it (giving a total of 2.4V) does that mean I can get away without a series resistor? Will that degrade the life of the LED by running it at that voltage? vik

Big Bwana8 years ago
Ideally you should use a 10 to 15 ohm resistor, this is assuming you want to give it about 20mA current, but in the real world people do overdrive them a little bit, so it should be safe, but you might not get the full rated life out of it but you should get like 90% .....
I always wondered what would happen if you were to take a normal superbright and run it on insane amounts of power and use something crazy like liquid nitrogen as a coolant.... Some day I must test that... With that circuit he should be fine, a small resistor would help but the actual damages caused would be negligible...
possibly it will degrade the life of the LED, in an ideal world it wont. but i'd put a 1k resistor to have a longer life.