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Topic: Running high power led's without drivers. (Read 7 times) previous topic - next topic

dhenry

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You've damaged your LEDs with all the 'experimenting'?


Most of the high power LEDs actually have a v-i curve that looks far more like a resistor than a diode, once they start to conducting.

fungus


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1. Are drivers really that important?


It depends. Drivers are useful in terms of efficiency, and longivity / thermal management. But they are not absolutely necessary in all situations.


If you want to work near the maximum light output you need a driver.

A resistor simply isn't good enough when you're on part of the curve where a variation of 0.1V can double the current.

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

dhenry

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a variation of 0.1V can double the current.


I trust you on that. But it would be helpful if you can show us all a high power LED where a variation of 0.1V can double the current near its rated output levels.

Just one example would be sufficient.

fungus


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You've damaged your LEDs with all the 'experimenting'?


Most of the high power LEDs actually have a v-i curve that looks far more like a resistor than a diode, once they start to conducting.



Sure, but it's almost vertical. Here's the curve for the 3W LEDs I installed in my hallway:



It doesn't take much extra voltage to overheat one.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

fungus


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a variation of 0.1V can double the current.


I trust you on that. But it would be helpful if you can show us all a high power LED where a variation of 0.1V can double the current near its rated output levels.


Well, OK... 0.1V might be hard to find. ;-)

0.3V though? No problem. See above...
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

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