They sorta don't like reverse voltage, at least the white ones, even with a good sized limiting resistor. Two LEDs back to back, or, if you only need 1 LED, connect a regular dioade to it reverse-parallel (anode of LED to cathode of diode, cathod of LED to anode of LED. This will limite the LED reverse voltage to 1 diode drop, about .7 volt. Lot cheaper than a bridge rectifier, too.
--Randy
Modeling the Reading Railroad in the 1950's
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I agree with Randy on keeping your DCC power for trains only. There's no particular reason not use separate power for signals or bumper lights, other than running the wires a bit further. Lighted track bumpers aren't particularly prototypical anyway.
As for bridge rectifiers, you probably don't need them. The D in LED stands for Diode, after all, so if you're giving it a square wave like a DCC signal, the LED will become a half-wave rectifier by itself. I've had no trouble with LEDs placed in passenger cars without rectifiers.
It takes an iron man to play with a toy iron horse.
Thanks Randy,
The application wasn't structures and I agree for that a seperate PS should be used. I plan on powering LED dwarfs and track bumpers only.
Bruce
It won't cause a problem with the DCC signal. But if you have a lot of lights to run, you might want to consider that the DCC power is relatively 'expensive' compared to just getting a simple power supply to drive all the structure lights. A DCC booster costs a lot more than a simple transformer witht he same output level.
I am thinking about powering various lights (actually LEDs) around the layout using track power via rectifiers. Is there a downside to this line of thinking in terms of affecting the DCC signal?
Looking back on the Walthers DCC passenger car lighting kit, I'm thing that it would operate pretty much the same way. I don't own any so I can't tell from experience.