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Led chip appropriate resistor

Mikeham98

Apr 12, 2022
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Apr 12, 2022
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I am trying to wire up some led Chips as headlights for an rc car my power supply is 4 AA batterys so total of 6 volts the led chips have a max of 3.6v at 1 watt I need help figuring out the best way to drop down the voltage
 

kellys_eye

Jun 25, 2010
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Jun 25, 2010
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The LED will be quite a drain on simple AA batteries however if you use a 12 to 22 ohm resistor you will still have VERY bright lights but at lower current. You will need a 1W resistor (minumum - best use 2W).
 

dave9

Mar 5, 2017
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How much space do you have available? A single series resistor (better two, one for each headlight LED) may be the smallest in volume, but far more efficient would be a current regulating LED driver (with minimum value balancing resistors in series to each LED), or two current regulating LED drivers.

I'm not aware of all the modules out there these days, nor how much available space you have in the car housing, but I might get something like this "260mA No Pin" style:

https://www.aliexpress.com/item/400...%3B-1%40salePrice%3BUSD%3Brecommend-recommend

There are more versatile drivers but their size grows above this tiny module above, fairly quickly.

Then there's drivers meant for flashlights, but those already set for as low as 1W (opposed to hacking it to get there) are somewhat rarer these days, but you could use either a buck regulator to power the two LEDs in parallel, or a boost regulator to power them in series. Any of these options would give better efficiency than using resistors, though as someone already mentioned, 2 x 1W headlights seems like a disproportionate load on an R/C vehicle that only uses a mere 4 x AA cell battery to power it.
 
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