heat

[NZRMac]

Hello

Do 1.5volt microbulbs get as hot as 12volt microbulbs?? my loco cab started to melt!!!!![:0]

[cacole]

The voltage rating of a bulb is not as important as the milli-Amp rating. As a general rule, a smaller voltage rated bulb is going to draw more Amperage and burn hotter than a higher voltage bulb in order to put out an equal amount of light.

[NZRMac]

do you know if dcc decoders pulse headlamps on & off rapidly to reduce heat/ current draw?

[cacole]

No, DCC decoders put a constant 12 Volt output on the bulb circuitry (white for the headlight and yellow for the rear light, with blue as the common). Electrical theory states that pulsing the output shortens the life of a bulb. The initial surge of electricity through a cold light bulb filament is higher than what a hot filament draws, and this initial surge through a cold filament weakens it, so putting a pulse onto the filament shortens its life because it cools slightly between pulses. Ask any movie theatre owner with chasing lights on their marquee how many light bulbs they burn out in one month's time. This is because the bulbs are constantly turning off and cooling slightly, and then being given a high Amperage shot of electricity to heat them back up.

[NZRMac]

any sugesstions then on how to mount bulbs in the loco?

[cacole]

My first choice for bulb replacement when installing a DCC decoder is a T-1 (3mm) 14 Volt, 45mA bulb on the end of 10" wire leads, that I purchase in bulk from All Electronics (http://www.allelectronics.com), Van Nuys, California, catalog # LP-6. These bulbs are priced at 2 for $1.00 U.S, or 40 cents each in lots of 100. I use liquid silicone (Goop) or Locktite Clear Household Silicone Adhesive/Sealant to glue the wires to the locomotive, and leave the bulb itself dangling in free air away from plastic. These bulbs do not get nearly as hot as a lesser voltage, higher mA rated bulb.

Another mail order source of bulbs in bulk is Micro-Mark (http://www.micromark.com), which sells a bundle of 100 clear bulbs for $39.95 U.S. These bulbs are 1/8" diameter grain-of-wheat size, rated at 12-14 Volts .075 Amp, with 6" wire leads, catalog # 82590-C. They also have colored bulbs in lots of 100 with 25 each of clear, green, amber, and red for the same price, catalog # 82590-4C.

None of these bulbs require resistors, which also saves space and money.

[NZRMac]

Thanks Cacole I'll see if anything the same is avaliable in New Zealand

Ken

[mcouvillion]

NZRMac,

I'm surprised your 1.5 v bulbs caused the cab to melt. I use 1.5 v lensed micro bulbs directly in the headlight holes on both DC and DCC and have never had this problem. Your bulbs must draw quite a bit of current!

As for mounting the bulbs and wire, I use small pieces of Scotch tape to hold the wires in the corners of the shell or otherwise out of the way. I use a small tweezer or hobby knife to hold the tape as I position it (the tape's adhesive does most of the work) and then press the tape to set it. It is easy enough to remove, and not a mess like stuff that needs to set before you can remove it. The bulb's wires are usually stiff enough to help position the bulb in the proper location. You might consider a 3-wire quick connect to allow you to remove the shell from the chassis easily without having to unsolder anything when you have to work on the engine's prime mover.

Mark C.