120w LED array, Resistor issues

RyanS

Dec 4, 2010
1
Joined
Dec 4, 2010
Messages
1
Hey, I'm having a few issues wiring up my 120w led array. The LED is rated at 34 volts and 3.6 amps. My power supply is rated at 40v 3.75a without fan and 40v 5a with fan. I'm not running a fan so I used ohm's law and figured i needed a 1.1 ohm resistor. So I put a 1 watt 1 ohm resistor in and fried it within seconds. I'm fairly new to electronics and I'm having a pretty tough time with this one. Any suggestions on where im going wrong???
 

LTX71CM

May 23, 2010
182
Joined
May 23, 2010
Messages
182
You likely used a 1/4 watt resistor, way too small. The resister for your LED would need to be 1.8 OHMs and at a very minimum 24 watt (mathematically) . Not a reasonable option really. You're better off using a circuit designed to drive high powered LEDs instead of using a simple dropping resistor.
 
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