for the electronics people

[greenbaywestern]

hey fellas!
I purchased some micro bulbs 12volts 30ma type from a well known MFG.
these bulbs are marketed as "DCC friendly with no heat generating plastic melting abilities"......well lets just say they lied!! question is what size resistor do I need to make these bulbs not melt the cabs of my units, but still retain some brightness?

thanks guys Paul B

back to LED for me!!!

[m a y o r 79]

If they are rated at 12 volts you dont need a resistor. Resistors are used to drop the voltage off the circuit board (or track power) when your using 1.5 volt bulbs. If you add a resistor to that bulb you'll end up with a really dim light.

Your best bet is probably to use a light tube in the headlight casting and mounting the actual light bulb inside the shell somewhere where the hot bulb wont directly touch the plastic.

[m a y o r 79]

Mark,

Track voltage on DC (or DCC) is 12-15 volts so with a 12 volt bulb there is no need for resistors to drop the voltage. (same bulb and wiring setup in the old athearn blue box locos) Putting a resistor on a 12 volt circuit is going to drop the voltage going thru to the bulb, which is going to make a dimmer bulb.

Your heat calcs are right, but if you want to use a resistor you need to change to a 1.5 volt bulb. Otherwise you'd have to mount a 12 volt bulb away from the plastic and direct the light to the headlight castings.

[greenbaywestern]

thanks for the input guys!!... so what to do with the bulbs that I have now..............hummmmm

[m a y o r 79]

That makes sense Mark, I wasn't following your post correctly.

[diburning]

12volt bulbs run hot enough to melt plastic regardless of the brand. I learned the hard way when I bought a non-DCC ready Kato RS-3 and ran it on analog on a DCC system. The bulb burnt a hole in the hood!