led too bright

Hello,

Recently had a DEI alarm installed that has a very bright blue LED alarm light in the dash. Unfortunately, when armed the light is super bright (too bright in my opinion). Is there a way to tone down the brightness? If so has anyone done this with success?

I read that putting a resistor in line with the positive wire lead would help too. Any suggestion on what resistor to purchase?

thanks, Jon

You can play with the resistances to get the dimness that you prefer but a 100 ohm resistor should do the trick. :)

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Gary Sather

Typical, for years we asked for brighter LEDs

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

what can I say--i didn't ask for a brighter LED. Original LED in my old car alarm was red and visible if you looked inside the car window. Now this super bright blue LED is much brighter and lights up the interior of the vehicle at night when it flashes. I just want to tone it down a little..

so I guess a 100 ohm resistor should be about right??

thanks,

It is very hard to dim an LED with a single resistor. You had better get an assortment of values to see what works for your LED. I am thinking it will take upwards of 1,000 ohms to even begin to notice a change.

Back when they were Clifford those LEDs were rated at 2.5 volts.
Using one from a 12volts source required 800-1Kohms.
Could I suggest simply substituting the standard LED for a lower output 2.5-3.5 volt LED?

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I used a sharpie and covered the LED. It's much less visible unless you're looking directly at it.

Well I decided to have a little fun and a little science experiment. I purchased a potentiometer and a bunch of different value resistors from the local electronics store. Cut power wire for LED, connected potentiometer and played with different resistor values by turning the knob.

"I am an idiot" post is definitely not an idiot--in fact, he's very accurate. It took upwards of 1.5k ohm resistance to see some dimming. In the end, I decided on approx. 3k ohm as the value I wanted. So, I took out potentiometer and soldered in a 3k ohm resistor. Works great! Instead of the led flasing HEY I'M HERE...it's now more like hey i'm here. Found a good medium between not too bright at night but also somewhat visible during the day.

jonb2] wrote:

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I am an idiot" post is definitely not an idiot--in fact, he's very accurate.

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Yeah - I think I might start legal action... misleading information or something like that.
Then maybe I'll finally get to have his name - or auction it off to others.


This example also demonstrated why "normal" resistive dimmers do not work for LEDs (ie - PWM is the only "near linear" dimmer that also suits other lamps)...
... and how sometimes investment in - or use of - a pot can save much trial and error.

I was going to reply above and suggest a 1k or maybe 2k pot. I'm glad I didn't if you found the solution to be 3k - even I would have expected a 5k pot a bit excessive. (Though I do know how "bright" LEDs can be with very low current, and blue is a strange color to work with at the best of times...)