Where to find info about resistors to use with 0402 coloured LEDs?

Flashlight Modding and DIY Parts
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I’ll soon be receiving a bare Lume Tri-LED AUX board and I’ll be adding some 0402 coloured LEDs for use in an upcoming FW3A mod project. I’ve not done this before, so I want to try it for myself.

Question is: Which resistor values do I need to use for the different colours?

Does anyone know of an online resource where I can look this up? If there isn’t one, an explanation about how I calculate the resistor values for myself would be much appreciated. Do-it-yourself AUX LEDs are new to me.

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2

Ice blue = 47
Warm white = 10
Pink = 200

https://www.reddit.com/r/flashlight/comments/111mo2m/comment/j9x34xl/

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3

The resistor values also vary based on the MCU.
The standard T85 based driver needs much higher values than the Lume1 which uses a T1634.

I used R=100, G=4K, B=3K on my recent FWAA

4

Thanks.
Is it a matter of trial and error, or is there a way of calculating from the MCU and LED specs?
As I may be trying different colours, it’d be good to know how to work it out myself.

At least I still know V = IR from long ago, but the question is what V I’m looking for and what I is needed.

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5

Typically the GPIO from MCU is based on CMOS technology and has a high level output voltage nearly to MCU’s power supply,For simple calculation you can use the power supply voltage of MCU and calculate the resistor value as R(KΩ)=(Vmcu-Vled)/Iled(mA) For most driver, Vmcu is come from a regulator and will be 3.3V. And Vled is the typical forward voltage of the LED,which can be measured via diode testing mode of a multimeter. And then you can look for datasheet for the LED which you want to use and get how much current you need to archive same lumen across three colors.

Warning: for most MCU, their GPIO ports can only handle about 10mA,so don’t put too much current on a port otherwise you might fried the MCU

6

Great, thank you!

7

For the lume1 driver VCC= 2.5V
Most current emisar/noctigon : 2.8V
common fet drivers : Vbatt-0.2V

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8

Yes, for me at least.

Every color has a different vF and appears different to the eye(example: Green would look way brighter than Red at the same current) so you can’t really go by current.

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