<VV> Re: LED taillights

JVHRoberts at aol.com JVHRoberts at aol.com
Mon Jan 30 17:50:55 EST 2006


 
Yeah, I know about the diode. My mistake. Sorry about that.. <G> 
 
The numbers you're quoting are for there Luxeon ls. The parts I listed are  
Luxeon llls. The Luxeon IIIs are rated at full power at 1400 mA. You won't cook 
 anything. But the resistors will get quite warm, so, make sure they aren't  
against anything that can get melted. 
 You need a fair bit of difference in brightness to be noticeable from  tail 
to stop function. With my circuit, you should have about a 6:1 difference,  
which is what commercial LED taillights run. 60 ohms on tail, 10 ohms on break.  
That works out to about 1100 mA on brake, and something just under 200mA on  
tail. 
The calculations are correct for Luxeon IIIs. 
Wait a few months, and the new Luxeon K2s will be out. These are nearly 8  
watts, and are over 4 times as bright as the Luxeon IIIs!! But are harder to  
mount, etc... <G>
 
 
In a message dated 1/30/2006 3:52:09 P.M. Eastern Standard Time,  
Bucketboss at aol.com writes:

>>>SNIP

There really should be another diode on the  tail light side to prevent  
back driving the light  circuit.
>>>>SNIP

...what he said... and the LED as well  as that poor 10 ohm,  10 watt 
resistor 
is going to take a beating  when the brakes are on @ 1.1 amp  
draw.....momentarily.

Those  are some wicked looking LEDs (on the website). Check me if I'm wrong,  
 
but from what I gather,  the designed MAXIMUM current for the   LXHL-LD3C 
star 
is 350ma. nominal and 385ma. peak. 

With the brakes  on,  that 1.1 AMPs would/should cook the resistor and  LED.  
Shouldn't it be say 33 ohms minimum STOP/TURN (brightest) to ground   and say 
another 33 ohms to the tail circuit. You still need a  resistor  wattage (for 
the 
grounded one) in the heating element  range.


Dave Fierek 






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