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Hi! I changed the leds from my instrument cluster, but the light is to bright. I want to change the resistors, but I dont't know which are and how many ohms to be...
Some help? Thanks
 

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I've seen write-ups on this subject, however it looks like a fair amount of work to get to the LEDs. If there are individual resistors for each LED, these should be un-soldered and replaced with higher resistance ones. The new LEDs will have a specification for the Voltage drop across them when lit, as well as a recommended current. For a rough example, if the supply voltage is 12 Volts, and the LED's operating voltage is 2 Volts, then 10 Volts must be "dropped" across a resistor. Supposing that the intended current is 0.01 Amp, then use Ohm's law to find the resistance needed: R=Volts/Current, or 10V / .01A = 1,000 Ohms.

You can also just measure the resistance of one of the removed resistors, and try doubling the value to see if the brightness reduces enough.
 

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ylwagon's advice still holds but now the resistor is sized based on the drop across all 3 LED's. For example, 12V supply, 6V voltage drop across all 3 LED's, intended current = 0.01 A (10 mA).

Use Ohm's law again R = 12-6 V / 0.01 A = 600 ohms.
 
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