As a lifetime rail historian and the president, project manager, and chief visionary of the restoration of Alaska Railroad 557, Pat Durand has done everything in his power to make the restoration a success. With the locomotive nearing operation we only had 3 of the old Amsco 250 watt 32 volt incandescent headlight bulbs. They are no longer manufactured and a wide search found that there were no remaining stocks nor was there a suitable replacement.

Pat has arranged for a special production run with the Specialty division of Bulbtronics, Inc. for 250-Watt 32-volt bulbs for the PYLE National and other locomotive headlights with parabolic reflectors and has formed a company to procure a supply of these bulbs for Alaska Railroad 557 and to also make them available to the railroad preservation community. The photos show the prototype bulb and the bulb under test.

If you are a serious purchaser of at least 60 bulbs, ordering details are in the classified section. If you are not prepared to make a bulk purchase, please wait until retail suppliers to the hobby make them available in retail quantities.

Note that this a personal project by Pat for the good of Alaska Railroad 557 and the broader preservation movement and the Engine 557 Restoration Company is not formally involved in this enterprise.

Lightbulb
https://www.bulbamerica.com/products/ev ... UAQAvD_BwE

Screw to g6.35 adapter

https://www.ledlight.com/e27-to-gx5-3_g ... erter.aspx

Then just wire in a 1 ohm 100w resistor

The 'new' correct bulbs are only $20 each. I'd have concerns that halogen lamp would not stand up to vibration. Projector bulbs were always fragile, a good bump while running would often blow them out. Remember running the cooling fan for 5 minutes after turning the lamp off?

That being said, I hope the new lamps are of high quality, so they not only last in use, but in storage. My experience with vaccum tube radios is that some of the new tubes leaked gas inside, and died early, when NOS tubes never had an issue even after decades in storage.

The vibration concern may be magnified by the conversion mounting, especially if the bi-pin socket is horizongal when fully screwed in. I don't know if there is a counterpart to 'rough service' filaments for halogen bulbs. I might consider 'soft start' capability (where a high variable resistance keeps the voltage and current to the bulb low until the filament has heated, then steps up to full brightness (and steps down with the headlight switched to dim, or turned off).

Another thing to remember about these bulbs is that they can be INSANELY sensitive to fingerprints, dust, or oil residue on the quartz 'envelope'. Don't touch them with your fingers at all during the entire process of R&R, or when cleaning the reflector or inside glass. The dust problem could be addressed by carefully sealing the headlight enclosure... but then the bulb may tend to overheat, so you may need to do some careful tinkering with HEPA-grade filter material for the vents.

Halogen bulbs were the standard for 20-30 years in transportation headlamps before all the HID and LED lamps took over, so they can be made plenty tough for whatever service. I assume projector lamps lack any supports on the filaments because they would cause shadows. In many headlamps the orientation of the lamp is specific for the reflector and the reflector is designed to even out the lighting.

Just a friendly reminder that the bulb and reflector work as a system. Before we start suggesting kluged alternatives (again), keep in mind that the position and emittance of the filament in relation to the parabolic reflector is what makes it work correctly as a headlight. Use a different light source, you need a different reflector.

The halogen bulbs in my 2004 Chevy Malibu drew so much wattage that they shorted across the elements on the plug that goes into the bulb inside of the plastic housing of the headlight, melting away the plastic until the bulb quits working because there is nothing to hold the metal elements in place. I'm lucky I didn't burn up the car. I had replaced those plugs several times by crawling through junkyards to find them, apparently it is a common problem with cars of that model (including the Saturn Ion). Last summer I replaced the halogen bulbs with LED bulbs I found on Amazon, $21 for a pair, and haven't had the problem since. So I wouldn't use halogen on a steamer headlight.

The simple, if not entirely 'serious preservationist', answer is that simply moving the socket fore and aft to position the filament correctly is all that's needed for a kludge. The reflector is parabolic: it will perform correctly as long as the majority of the filament is at the optical focus of the concave mirror.

I am more interested in practical 'screw-in' LED replacements that are sized, and 'heat-sinked', for the ~310,000 candlepower that good steam-era headlights were supposed to provide, with phosphors chosen for a correct color (e.g. 'Golden Glow' when we can't use uranium glass in a reflector).

And watch that resistor go up in smoke. Standard design practices call for at least twice the total load of the entire circuit or 500 watts. That's why the 3.15 ohm dimming resistors are so big.


And still end up with a kluge.

After looking over the linked items it appears the halogen lamp would have to be moved forward into the reflector 1 full inch for the light center to be in the same position as the G-25 bulb. Does your headlight have that range of adjustability? Another challenge may be that with the filament orientation across the bulb in the halogen rather than along the length as in the G-25, placing the halogen at the focal point of the parabola may well be quite touchy.

My suggestion (worth what you've paid for it) is to be that "serious preservationist" and honor the effort put forth by this selfless individual and purchase the proper lamps. If not now then from the distributors who will be making this order possible. You not only help yourself but the entire preservation world.

Rant Off ....................mld

Your math is a little off. Assuming perfect 24 volt 250 watt bulb in exactly 32 volt circuit...

250 watts / 24 volts= 10.4 amps
You gotta waste some, 10.4 amps / 8 volts = 1.3 ohm 'ideal' resistor
10.4 amps times 8 volts is 83 watts dissipated in the resistor
you typically double the wattage when sizing a resistor, so 83x2 watts is a 166 watt resistor needed.
500w is OK but serious overkill.

Then why do steam locomotives use 500 watt resistors? One current manufacturer lists their 500 w ceramic resistors as 1 5/8" outside diameter by 10.5" length. Their 240 watt are 1 1/8" diameter by 6.5" in length. The 500w dimensions almost perfectly match the dimming resistors used on a locomotive I am working on.
I said size for total load of the entire circuit. That 100 watt resistor even dissipating 83 watts will not last long & I think we can agree there. Even a 200w resistor will get quite hot at 83w. The point I'm aiming at is double the entire circuit, not just what you're trying to waste in heat.............mld

Could you cite the source / datasheet for this 500W number with the 1-5/8 x 10-1/2 " resistor?

Those dimensions sound more like an industry-standard 250W resistor such as Ohmite, Dale, Milwaukee, etc.

Resistor ratings are tricky. The nominal rating is for a certain temperature rise (without looking it up, I think it is about 400 degrees F) over 25C ambient. Significant derating if resistors are clustered together or if ambient is elevated. Likewise, significant capacity increase with low duty cycles.

I've never heard of sizing a power resistor based on the total power consumed in the entire circuit. You may be applying a factor safety by doubling the size, but that is still based on what the resistor itself dissipates. The power being consumed in the bulb is not making the resistor hot, unless they are in the same sealed compartment.

High power DC-DC inverters have been available for several years. Far more efficient than dropping resistors. Just sayin'...

Patrick Durand asked me to post this update -

Good news on the Heritage headlight bulbs. To date 16 railroad operators have committed to stocking orders for the Part #BT250P2532V bulbs. The special order is going forward.

If you want to participate in this special order see the classifieds at viewtopic.php?f=2&t=48493

(I'll be posting some slightly updated information in the classified announcement above later today.)

557 Pyle Enterprises has announced that the heritage locomotive headlight bulbs have been manufactured and are now stocked in Chattanooga, TN. They are being shipped to those who pre-ordered. They can also be ordered by those who missed out on the pre-orders. See the classifieds for details.

Credit for this effort goes to Patrick Durand, Project Manager for the Engine 557 Restoration Company. Having only a couple of new bulbs in stock for 557's use and finding that there was no longer a source for old school locomotive headlight bulbs he personally established 557 Pyle Enterprises for the sole purpose of having bulbs manufactured and available for 557 and the rest of the heritage rail world. Having met that goal and ensuring a long-term supply for the rail heritage community, he is now able to personally retire from the light bulb business.