In the March 2009 issue Carl Swanson had a great article about changing out the old headlight in a loco and installing LEDs. At the time, Train America Studios was the supplier of a neat little board that powered four LEDs. Since Train America Studios is no more, does anyone supply a similar board/LED product? Would it be just as well to wire LEDs together (for dual headlights and ditch lights, etc.)? And if so, what are the specs for the LED that would work with variable voltage AC? Thanks!
Check out Evans design http://www.modeltrainsoftware.com/ I use 3mm Led's. These work on 7-19 volts.
Bill
First LEDs do not work with A.C.. The PIV is close to Forward Voltage. You need to place a rectifier in series and direction you want the led to fire. If you want the led on all the time place inverse LED and diode in parallel.
I will dig up the catalog I have for LEDs and other electronics.
What is most important is the dropping resistor. Take your highest track voltage. Most LEDs run at 30ma max. I always figure for 20 to 25 ma. You lose very little brightness until close to non-fire.
R = E / I
You may want to look at what I posted before you say they don't work on A/C
Reread what you referred to.
" The LED’s are made to run on DC power. If you are running AC, DCC or plan to run DC in reverse (backing up) we recommend our 5-19 Volt Universal LEDs."
I stand by my information.
I know Leds work on dc. I didn't mean you can plug a led in to ac and have it work. But you can buy them just like I said that have the rectification work done. Then they will work on ac.
Thanks for your help. I just ordered 2 of the 3mm Universal LEDs, prewired, from modeltrainsoftware.com. $8.49 with shipping so its definitely worth an experiment! It looks like the perfect solution, even a step-by-step guide for doing a loco. Thanks again.
Five millimeter LEDs are very close to the diameter of the plastic light pipe found on many O-gauge locomotives. A 5-millimeter LED in place of the light pipe will produce much more light and a more realistically narrow beam than simply putting it in place of the incandescent lamp. They can be turned down a little if needed to make them fit. You can also cut off the tip and reshape it to the same domed shape of the original headlights. Polish it with toothpaste.
I strongly recommend using LEDs modified to imitate the color temperature of incandescent lamps. One source of these is Richmond Controls: http://www.richmondcontrols.com/
For anyone wiring his own LEDs rather than buying a ready-made assembly, calculating the ballast resistance and its power rating is not straightforward. My article in the September, 2008, CTT however includes tables that I hope can simplify the process for you.
Bob Nelson
Be very careful if you are replacing Locomotive headlights with LEDs. I just learned a lesson the hard way. I used Evan Designs and the LEDs are great, good color, very bright, and include a postage-stamp sized (smaller really) pc board inline that I believe is the resistor/rectifier (hey, I don't know electricity!). But when I attached them to the pc board contacts on my locomotive, they did not light. I later discovered that I had cooked that part of my PC board so now even the old lights don't light. There went the directional lighting! Too bad, that was a switcher! The rest of the PC board's functions were not affected, and I wired the the LEDs directly to track power. Now the front and rear lights are just on all the time. I don't blame Evan Designs, but I was told the LEDs drew too much power for the board to supply. I thought LEDs use less power???
An LED uses much less power to produce the same amount of light as an incandescent lamp. LEDs and incandescents vary quite a bit among themselves in efficacy (light per unit power). But what makes a bigger difference is that an LED is almost always used with a ballast resistor to control the current; and the resistor consumes much more power than the LED itself, especially when designed for the variable voltage of a toy train. You can do it without the resistor; but it's complicated and expensive and usually not worth the trouble unless you're trying to illuminate a room with an LED array.
About the easiest way to get directional lighting with LEDs is to wire two of them in anti-parallel (anode to cathode, cathode to anode), with a single ballast resistor, connected to the can-motor terminals.
What Lionelsoni says works. I've converted a Williams GP9 to LED headlights by placing them, in anti-parallel, and the balast resistor across the can motor terminals.
If there are resistors on the motors, does there need to also be resistors on the LED wires as well?
Watch my videos on-line at https://www.youtube.com/user/AndrewNeilFalconer
I can't imagine why there would be resistors on the motors; but the anti-parallel pair of LEDs needs to be in series with a suitable ballast resistor. Then that series-parallel combination is connected across the motor terminals. Look up my CTT article to see how to select the proper resistor.
What you think are resistors across the motor are probability capasitors to elimiate electrical motor noise.
Norminally a capasitor is placed between the brush contacts and one each from the brush contact to the case/jacket of the motor.
Putting a resistor in line or around the motor makes no sense.
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