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please help! connecting led to a led driver?


  I bought 1w led driver : MR16 1*1W 320~350mA Constant Current Regulated LED Driver (8~40V Input) and put it in the mr16 socket 12vac, and then I measured output voltage - it was about 9volts, so if I want to connect 1w luxeon, I'm afraid it would burn out, what should I do? Would it be possible to put 1 ohm 1w resistor since it's a 1x1wled driver ?  Led calculator says (for 9v input): 18 ohms, 2.2wats. thanks !


This regulator of yours is designed to supply constant current to a load, so just looking at the open circuit voltage is not going to tell you much.  How can you tell if the current be being regulated if there is no current flowing?

Anyway, this idea of yours of to put a load on the output, and then measure the current through the load, this is a good idea.

For example if you put a 1 Ω load across the outputs, and the regulator does what it's supposed to and drives 350 mA through it, then the voltage across this 1 Ω load would be... you guessed it:  V=I*R = 0.35 V, and the power dissipated by this load would be (0.35)2/1= 0.1225 W.

And that's a load that should be easy for your regulator.  If you want something that is a closer match to the intended 1 watt white LED, try a 10 Ω resistor.  You'd expect the voltage across that to be V=I*R = (350 mA)*(10 Ω) = 3.5 V, and the power dissipated to be (3.5)2/10 = 1.225 W
xtony666 (author) 6 years ago
thank you for your answers, they were very helpful to me :D
frollard6 years ago
It outputs 9 volts because its trying to force the circuit to draw 350 mA of current. If you put an LED that expects 350mA of current in the circuit (no resistor) -- it will regulate the current for you. It regulates the current by constantly adjusting the voltage according to Ohm's law.