Atlas N scale GP-7's & white LED's

Discussion in 'N / Z Scale Model Trains' started by Blake, Jun 15, 2003.

  1. Blake

    Blake Member

    I had allot of trouble getting these white LED's to work in my Atlas GP-7. I just replaced the old ones in my Kato F-3's and RS-2's with no problem. I found that most (or all??) of the white LED's are rated at 3.3 vdc .030 amps. The Atlas led's are 1.5 vdc. The problem is, by the time you go fast enough to get the lights to come on your at Mach 1!! I tried all kinds of resistors and found that you can replace their LED with a white one, and replace their resistor with a piece of wire. Just be sure not to really crank up the power or you may burn them out. I know that the problem lies in the Atlas motor, but spending another $20 just to get the lights to work is a bit much. Has anyone got a better or different solution.
  2. Clerk

    Clerk Active Member

    Take the old resistor to Radio Shack and check the value. Then get a resister at 1/2 the value and connect it in series with the LED.
  3. ezdays

    ezdays Out AZ way

    Shorting out the resistor is not a good ideal considering the price of white LEDs. You should always have a current limiting resistor in series with an LED, even if you are running at their rated voltage. Any change above their rating will cause it to draw more current. LEDs will burn out if they draw too much current above thier maximum rating. Normal LEDs take a bit over 2 volts so the rest of the voltage has to be dropped across a resistor. If the Atas LEDs are rated at 1.5 volts, and the replacement one is 3.3 volts, then you can just take a same size resistor and solder it across the existing one, and that will effectively cut the value in half. If you cannot read or measure the value, read the color stripes starting with the stripe closest to one side, post them here and we can tell you the value. I'm guessing it's somewhere around 600 to 800 ohms and is a 1/4 watt.

  4. leghome

    leghome Member

    Jim Hinds at Richmond Controls has come up with Golden White led that really looks more natural. It is bright like the while leds but does not have that bluish cast to them. they look fantastic IMHO. Here is an early message I received opn one of my e-mail lists

    "Some of you who have considered purchasing the golden-white LEDs but haven't seen them yet might want to have a look at a photo that Peter Vanvliet made. There is a link to it on the Richmond Controls website (Thanks, Peter!) if you click on Golden-White LEDs in the left column, then find the link and click on it. Peter shows the golden white LED in his PRR E8, next to an E8 with a bluish-white LED and another E8 with a dim yellow LED headlight.

    When people order the golden-white LEDs I include a sheet of recommendations for using them without destroying them. The same information applies to those of you who may have bought other white LEDs and are in the process of retrofitting your locomotives. My recommendations on the care and feeding of white LEDs are in the form of a WORD document on the website that you are welcome to print and use if you are uncertain about using white LEDs. The advice applies to the golden-white ones, the bluish ones, the stark white ones, etc.

    It has previously been reported here and elsewhere that people substituting white LEDs for yellow LEDs in locomotives find that they die rather quickly in some circumstances. Even with the price down to $1.50 each, that's still a lot of money to be throwing away. I hope the suggestions will keep more LEDs from being destroyed."

    Jim Hinds

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