Re: [Amc-list] Blue LED tamed

[Keleigh Hardie <keleigh3000@xxxxxxxxx>]

I think the problem here is that LEDs use next to no current, so the 
resistor doesn't have anything to work with. I have an LED flashlight, 
it starts at three volts, and down to about two the brightness hardly 
varies maybe only 10-15 percent. I'm not sure changing the voltage to 
your LED within it's operating range would vary the brightness much. The 
only two options I can see are A) pulse width modulation. This basically 
flashes the LED so that it's off 50, 60, 70 etc. percent of the time. It 
would have to be very fast so your eyes perceive it as a dimmer steady 
light. Or 2) find a dimmer blue LED...

Keleigh

Wrambler242@xxxxxxxxxxx wrote:
> OK, I give up!
> :] Since I now have a too bright led with a dead resistor, what do I install to get it as dim as possible and still lite???!!!
> 150 ohms? 15K ohms? Anyone know what the resistance is of say a 194 lamp? Maybe I can use some of those to gauge what resisitor I need?
> I just need a blue glow for a high beam indicator, or I'm going to surrender and use th eleftover red one I have! It ain't broke and is fa dimmer than the blue laser!
> --
> Mark Price
> Morgantown, WV
> 1969 AMC Rambler, 4.0L, EFI, T-5
>
>  -------------- Original message ----------------------
> From: Tom Jennings <tomj@xxxxxxx>
>   
>> On Sun, 4 Mar 2007, Widiker, John D wrote:
>>
>>     
>>> This Blue LED is not a tiny cute one, it's a freaking laser, it's burn
>>> your retinas bright, 200 did absolutely nothing at all. The same one he
>>> has we used 15K on and it was tolerable and hasn't had an issue in 3
>>> weeks of use.
>>>       
>> Maybe you mean 150 ohms?
>>
>> But but... 15K ohms (15,000) means 100 times LESS current than
>> 180 ohms... any LED ever made since 1970, with 15,000 ohms on
>> 12 volts, you won't be able to see it.
>>
>>  	      E
>>         I =  -----
>>                R
>>
>> I is current. E= 12. Bigger resistor R, less current. Less
>> current, less power, less brightness.
>>
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