SMD LED's

[MikeyChris]

I am quite familiar with using "through hole" LEDs, but haven't used SMD LEDs yet. So I was wondering what the consensus is on the various sizes (0602, etc.), brightness and functionality. For example, I am adding interior lighting to some cabeese. I did all the prep work with the wheels, wipers, wiring, etc., and breadboarded a constant current driver with capacitor circuit that keeps the LED brightness pretty constant even with changes in track voltage (I run convention DC) and dirty wheels/track. Then I noticed that even difused LEDs are pretty directional (they work great for headlights, not so much as interior lights). So I thought maybe 3 or 4 SMD LEDs, mounted on the ceiling of the car would give a fairly nice look. I plan on spraying the "window glass" with dullcote because there will be no interior detail. Has anyone got any experience doing this? Again, I'm running straight DC, but that doesn't really matter as long as I can power the LEDs, right? I have that covered, but not sure of the best way to get optimum interior lighting. Any tips on using those passenger car interior LED strips? Thanx.

[rrinker]

 SMD LEDs tend to be very efficient - so where a 1K resistor might give a nice glow qwith a 3mm through hole LED at 12V, an SMD LED may look like the center of a nuclear reactor. So you may have to use more (4-5x more) resistence than you would for an otherwise similarly rated through hole LED.

 Not really practical for DC, but I plan to fit at least some of my cabooses with a DCC decoder to control the lights. In my era, the conductor still used an oil lamp for light, but the markers were battery powered (no generator/battery on the caboose yet). So a nice steady on to light the markers, and perhaps the firebox flicker effect for an interior light, mounted at one end where the conductor's desk would be. Perhaps witht he decoder configured for incandescnt bulbs - that usually gives a less than desireably effect with an LED, but firebox flicker is a bit too much for the lights the conductor is supposed to be using for paperwork, so a more subtle flicker where the light never actually blinks off.

                            --Randy

 

[RR_Mel]

I’ve used all sizes of LEDs and personally I would go with 3mm wide angle LEDs for your caboose and or passenger cars.  I use multiple wide angle LEDs at very low current closer together for more realistic lighting.  Most are drawing less then 2ma.

 

 

The only thing I use the tiny 602s for are mainly for lanterns.

 

 

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.