What Resistor do i need for 10W 5V 1050mA led

X-360

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What Resistor do i need for 10W IR 850nm Infra-red Round High Power LED Chip Bead bulb Lamp 5V 1050mA
 

Alexander47

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Depends on your supply voltage.
If the supply Voltage is 12V
12V - 5V(voltage of the LED) = 7V
7V / 1.05A = 6.6 Ohm
Resistor has to be rated 7V*1.05A= 7.35W minimum.

-> use a LED Driver, either buck or boost depending on your application.
A resistor is not a good option for high power LEDs.
 

Dave_H

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What supply voltage are you using? Agreed, driver is probably best, at 12v you will be losing
almost half the power into heat.

Is this the one?


Dave
 

X-360

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What supply voltage are you using? Agreed, driver is probably best, at 12v you will be losing
almost half the power into heat.

Is this the one?


Dave
Yes that's it Trying to make it as small possible 3V button Cell maybe if it could work or hook it up to a USB power bank somehow
 

X-360

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Depends on your supply voltage.
If the supply Voltage is 12V
12V - 5V(voltage of the LED) = 7V
7V / 1.05A = 6.6 Ohm
Resistor has to be rated 7V*1.05A= 7.35W minimum.

-> use a LED Driver, either buck or boost depending on your application.
A resistor is not a good option for high power LEDs.
How bout using a capacitor?
 

JimmyM

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An LED's resistance drops as it warms up. Using a fixed resistor will cause it to start drawing more current as it runs. Then it gets warmer, then draws more current, etc. You need a fixed current regulator. You can find these pretty cheap AND small. Look for MR16 LED driver or bi-pin LED driver. Stuff like that. They have little resistors on board that you can swap out to adjust current.
Here's a link to where I used these to drive LED conversions in my camper.

https://www.popupportal.com/threads/camper-led-conversion-how-to.90098/
 

Dave_H

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A 3v coin cell (I assume you mean) has nowhere near the capacity, and insufficient voltage to drive the LED, scratch that.

A USB li-ion pack of sufficient capacity could supply 5v at say 2A which could drive the LED, depending on expected run-time, but it's still problematic. LED still requires current regulation, but its forward voltage may be too close to 5v to do it with a resistor. Even electronic regulation needs some overhead.You might find a driver which does this, but easier to use one with higher input voltage, say 12v as suggested (if that's workable).

Possible specs for driver:

- input 12v (or whatever range you can use, but higher than 5v).
- output voltage includes LED's Vf 4.5v-5v range.
- driver constant current output 2A (for 10W), or lower depending on your needs; possibly
settable.

Dave
Yes that's it Trying to make it as small possible 3V button Cell maybe if it could work or hook it up to a USB power bank somehow
 
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