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Bob Nelson
QUOTE: Originally posted by lionelsoni I haven't seen the OGR article; but replacing headlights by LEDs is not hard. I have done several, both modern and postwar. The golden-white LEDs are much better. It also helps a lot to put a capacitor across the LED. They turn on and off instantly otherwise and look unrealistic compared to incandescents. The value is not critical--a few hundred microfarads. You probably can't find a capacitor with too low a voltage rating. Then drive that parallel combination through a resistor, with a diode in series (e.g., 1N4148) if you're using AC. (AC will damage LEDs. They can't stand much reverse voltage at all.) The white LEDs are so bright that you don't need much current, just a few milliamperes. You can actually turn down an 8-millimeter LED to fit into a Lionel headlight hole. And you can flatten the tip and polish it with toothpaste. Just don't cut into the chip inside. I had an article a while back in CTT about adding directional lighting to postwar locomotives. Instead of connecting the lamp between the frame and the pickup, as lionel did, you reconnect it between the frame and one of the motor brushes. The incandescent lamp does come on, but very dimly, in reverse, since incandescents are very sensitive to voltage. This will also work with LEDs, but you will probably have to put extra diodes in series to soak up the voltage that is still present in reverse. Using LEDs, I feel no need for regulating the brightness of headlights, as I would with incandescents. The brightness does vary with voltage, but not nearly as much. But, beyond that, the color remains exactly the same at different voltages, so that clue to voltage changes is absent: They look fully lit over a wide range of voltage.
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