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Light bulbs too hot!

  • Kelley
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2 years 5 months ago #18007 by Kelley
Kelley created the topic: Light bulbs too hot!
So I finally got my 3 F 7s back from getting DCCed. Pretty cool as ABA, and they have reversing lights and mars lights. They look really nice but i noticed there was a lot of bleed though the shell and while I was looking at the spots the light went though, I touched the nose and was surprised how really really hot the nose was. Enough were if it were to stay on a while I am sure it would melt/distort it eventually. When I picked them up, i was told there were grain of wheat bulbs used and not LEDs, I am thinking for the headlight i could use LEDs, but Mars light might not work right using them. Anyone with experience with them? Any way to make some kind of heat shield or heat shrink so my engines dont melt? (I went though the melting car thing years and years ago with N) Thanks!

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2 years 5 months ago #18009 by markm
markm replied the topic: Light bulbs too hot!
All the Z scale "drop-in" DCC use LEDs and personally I think that the Mars light with LEDs looks more realistic. If you haven't done a conversion to LEDs before the Digitrax Decoder manual V2.1 (pg. 21) is a good reference. I find that light bleed through is a bigger problem with LEDs. On the "T: style LEDs I use black heat shrink or "spaghetti" insulation to block side illumination.
I can't think of a good heat shell. I've used adhesive aluminum foil on the inside of a shell, but that just distributes the heat .


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2 years 5 months ago - 2 years 5 months ago #18013 by garthah
garthah replied the topic: Light bulbs too hot!
be careful with tinfoil, on split chassis bridging the gap between the two halves of a chassis will create a short. a couple of layers of flat black or engine black paint will usually do a good job of cancelling bleed through.

cheerz Garth

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2 years 4 months ago #18017 by SJ-BAZ-man
SJ-BAZ-man replied the topic: Light bulbs too hot!
If there truly are light bulbs in there, I suspect they are still the MTL originals and if so, the applied voltage from the DCC boards rectified source is ~12 or more volts. Will in some modes, like MARS or Rule 17 (Dim in Reverse or Stopped), the effective voltage from PWM (Pulse Width Modulation) will keep them cooler from lessor full on power.

Yep, LED's would be cooler, just need to insert a resistor, somewhere between maybe 220 to 1000 ohms, 1/8 watt, depending on how many millicandela the LED produce.

The incandescents smooth the steps used for the MARS effect, making them seem more realistic to me. The LED', you can more clearly see the steps used to simulate bright to dim. NOTE: most all decoder manufactures have an LED setting for the light Effects. This is because the normal PWM goes to zero or near 0 duty cycle (i.e. virtually no 'on' time) so the LED"s. being instantaneous, can perfectly go all the way off whereas the incandescents cannot shut off as fast.

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