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Is there a way to get rid of fast flashing with LED bulbs outside of wiring a resistor in? i found splicing in the resistor works fine...till the resistor dies. i welcome any opinions...and yes i know the simple solution would be putting factory signal bulbs back in.
 

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Better quality resistors. They really shouldn't be failing if they were designed for that purpose. Do keep in mind they'll get hot when they are on and plan accordingly. Make sure what they are around and touching can handle the heat. As well as there's a way for them to get rid of the heat.
 

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It sounds as though you're exceeding the power rating of the resistor. The power that must be dissipated by the resistor is:

P = V^2 / R ("V-squared divided by R")

or

P = I^2 * R ("I-squared multipled by R")


P is the power (in Watts)
V is the voltage across the resistor (in volts)
R is the resistance (in ohms)
I is the current through the resistor (in amps)


I'm assuming the LED is on continuously. If so, the resistor must continuously dissipate the power calculated by either of the above equations.

For example, if the resistor is rated at 1/2 watt and it's being asked to dissipate 2 watts, it won't last very long!


- Joe
 

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Yeah, and the voltage in a working car isn't "12", but can be closer to 15. A 300 ohm resistor will dissipate a little under half a watt at 12V, but it climbs to 3/4 of a watt at 15!

But I'm assuming you're buying resistors designed for this task and not just picking up something at Radio Shack. Nothing wrong with the Radio Shack resistors, but you do have to do some more engineering to make sure you're not abusing them. And you never really want to run the full rating all the time. If you're getting close to the rating, bump it up to the next level.
 

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Discussion Starter #6
thanks for the input all. yes i purchased resistors made to stop "fast flashing" with led bulbs. i'll check with the vendor on the specs for the resistor as chevy guy made a good point.
 

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Also keep in mind that the wattage rating of the resistor is based on a specific ambient temperature (most likely 25 deg C) and the resistor not being in an enclosed space (i.e., heat from the resistor is allowed to dissipate freely into the surrounding air). For any other conditions the wattage rating is reduced ("derated").

I agree with ChevyGuy: step up to the next higher wattage rating. You might even want to go to a rating at least twice the calculated wattage.


- Joe
 
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