Re: [DML] LED Center Console Burnout

["Robert Lingo" <rlingo@xxxxxxxxxxxxxxx>]

>Elvis wrote:
> what kind of LED's did you use ?

I bought them off EBay about a year ago. All I know is they came in a static 
proof bag, they are rated at 3.5V, and have a 25000mcd/LED.  I just solder 
them together and go.

> Are those non automotive LED's with integrated current source or
> resistor ?

I have 16 of them installed on my motorcycle (12 volt system).  They have 
been burning true for over a year now with no burnouts.  Running four LEDs 
per series (3.5Vx4)=14V.  No resistors anywhere.


>Then your are breaking one of the basic electronics laws
> that says - always use a resistor to limit the current thru a LED !

Ignorance is bliss.  I tried to learn something about Ohms Law when I 
installed them on my bike.  I didn't learn very much.


> But on a 12V system you
> definitely need the resistor ! A LED is not a bulb, it's a diode !

I didn't think I needed to restrict the Voltage with a resistor because the 
LEDs pull 3.5V resistence on there own.

> LED: if you drive it with let's say 3.3V or 3.4V, the difference can be 
> like
> 1000% !!!!!!!

So if I only had one led connected to the 12V power source, I would then 
need to restrict the voltage by 8.5V with a resistor. So my thinking is 
3.5Vx4 is leaves me with nothing to resist .   I don't know how many laws 
I'm breaking here.  It makes since to me and it seems to work.

> This is why they burn very fast without resistors in series to it.
> (again - only if it hasn't it already integrated !)

That's why I put them in series.  If I ran them in parallel I would then 
need resistors for each circuit.

Lingo #2034 





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