Some time ago, probably in Model RR magazine they talked about "Constant
Lighting" for locomotives or even passenger cars. Anyone know how to do it?
Is there a kit of some kind or whatever? Even the style were the lights are
one even when not moving or parked.
Also I've noticed in my "B" units there are usually portholes. In normal use
would there have been any light showing from these "window" portholes?
There are a number of answers of varying complexity:
- DCC does the job automatically by applying 15-18 volts AC to the rails full
- A diode bridge in the motor circuit will provide 1.5 volts for head and tail
lights on DC powered locos.
- three extra diodes will provide directional lighting.
- Coaches and unpowered vehicles can have a reasonably simple capacitor and
voltage regulator circuit for (say) 6 volt bulbs.
The problem there is that more amperage has to be supplied to provide the
wattage at the lower voltage and some track voltage must be lost as heat.
- If your controller uses PWM (12 volts chopped to give the effect of lower
voltages) then a diode and capacitor in each vehicle will provide full voltage.
- I use either 12 or 15 volts PWM as above plus a zener and transistor to switch
coach lighting on and off. (12 volts off/15 volts on)
- High frequency AC superimposed on DC traction current.
DC motors have too much impedence to be affected by high frequency AC but light
bulbs don't mind at all.
A choke is required to block the AC from the controller and a capacitor in
series with a bulb will block DC traction current.
Most published circuits are near the top of the audible range, due to the
limitations of older transistors, but frequencies up to 30khz are quite
practical today. (drive the dog/cockroaches crazy!)
I doubt if A or B units would show light from the portholes normally.
The light can be on in the cab, but there is a door between there and the
machine room/engine room. That room, with the portholes, would have lights with
an on/off switch. The driver should have no reason to be in the machine room
while in motion unless he is confronted with an inevitable head-on collision.
There are a number of *very* good reasons to be in the engine room of an
F-unit or other carbody diesels whilst the loco is in motion, none of
them connected with an imminent collision.
As one example, FTs had manually-operated radiator shutters in the
intake ducts, which could only be operated from inside the engine room.
The also had local control panels in the engine rooms, which included
alarms for low lubricating oil pressure, hot engine, wheel slip and hot
journals. These required periodic inspection by the fireman while running.
AFAIK more modern F-units had automatic radiator shutters, but the local
control panels remained much the same. At any rate, it was common
practice on US railroads, and elsewhere, for the fireman to go back and
check on the condition of the units while running.
Also, any carbody diesel with steam generators for train heating would
require the fireman to go into the engine rooms while running to
One other reason to go into the engine room while running - on carbody
units that's where the toilet was.
But since operation could very likely be during night time - lights would be
required anyway. [But I'm just wondering and speculating with my question
Certainly EMD (or others) didn't plan on using the portholes for maintenance
Absolutely. I reckon the portholes were provided to make the interior a
little less claustrophobic by day or night. Our 44 class Alco cab-units
were rather uncomfortable by comparison, having no portholes or any
I wouldn't think so.
Well, yes, they were, but, ornamental or not, if the engine room lights were
on at night, the light would show. Being unnecessary doesn't make them
as windows. During daylight hours enough light would usually come into the area
remove the need to use the lights. Most of us tried to avoid being in the engine
room anyway, unless it was absolutely necessary. Hot, noisy, smelly, nasty.
No, they allowed light inside the otherwise dark carbody. FT's had four
on each side. F2's and phase-1 F3's had three on each side, later models
had only two on the "A" units, but still had three on the "B" units.
In many cases the portholes could be opened for added ventilation. On
the FT units, some had a seventh porthole (4+5) for the hostler to stick
his head out while moving the loco (most FB units had minimal operating
This also addresses one of my pet gripes. Lots of people like the newer
"F" unit models because of their 'see through' side screens. While these
DO allow one to see the carbody structure and sometimes the radiator
sections, one should NOT be able to see clear through the units from
side-to-side as most of the models allow. These screened openings all
had sheet metal ductwork behind them that normally completely closed
them off from the carbody interior. You could NOT usually see through
the units, nor see out of them from inside. This left the interior
almost totally dark, except for the portholes. I've been in a lot of "F"
units and can attest to this. I'm not so familiar with the "E" units
(only been in a few, long ago), but as I recall, and I otherwise
surmise, they were much the same.
There were electric lights inside the carbody. If these were on at
night, you could see light out the portholes. It was NOT a bright light,
however, and pretty dim really.
Sort of true, though routine running maintenance on the mechanism was
possible on the "covered wagon" carbodies, and was not uncommon. Also,
it was not at all uncommon for crew to pass through the units as needed.
On passenger trains the front doors on the "A" units allowed for direct
access to the train.
Thus the interior lights (quite dim) might well be on at times while the
train was moving .. not to mention just fogetting to turn them off.
That sounds rather "hit and miss"!
It's likely to be like the red light on the car dashboard that tells you your
engine has just overheated/run out of oil/stopped generating.
Ok, we didn't get Diesels here in NZ until the 1950s, by which time the
indicator dials and knobs were all extended to the drivers cab. My mistake!
So did the F units have light switches in the engine room for such occassions,
or were they on all the time?
It was on the engineer's side in the rear corner of the unit. E units had the
"hopper" as it was so euphemistically called crammed in among the train boiler
equipment. If you had to "use it" you found another way if you could.
Remember Peteski, the thing was a dry hopper. It was literally nothing but
galvanized steel, sheet metal cone, with the big end up, kinda like a funnel.
was something that was reminiscent of a toilet seat on the top of it, and the
end was a hole in the floor; that's right, just a hole in the floor, nothing more
than an outhouse on wheels. There was no partition, no door, no
You just plonked your butt down on the thing and did the necessary right in
anybody else that might be in there, or come wandering through.
Rather primitive, I always thought. Not only that, but you had better remember to
bring your own "accessories" or you would find yourself up s * * t creek without
paddle, so to speak.
In short, they were miserable and disgusting, and were relegated to use only in
direst of emergencies, which of course only made them even worse.
Road switcher type locomotives had the appliance in the short end, if they had
all, which some did not.
That sounds nasty! Actually, when I used to travel on Polish Railways
in the 70s, those had a slimilar toilets in the pass. cars. When you
"flushed", it opened up and you could see the roadbed moving under you.
Of course, there were signs which stated not to use the facilities
when stopped at the station...
When I used to walk the tracks, I sometimes came upon "gifts" left by
Ah, those were the days...
Maybe I was thinking of the more modern diesels (like F40PH).
For DC power, this (whatever it is/was) must have used a battery to power
the lights, since you have to cut power to the tracks to stop the train.
Of course, with DCC power, what you describe is SOP.
-- Bill McC.
| > Some time ago, probably in Model RR magazine they talked about "Constant
| > Lighting" for locomotives or even passenger cars.
| > lights are one even when not moving or parked.
| For DC power, this (whatever it is/was) must have used a battery to power
| the lights, since you have to cut power to the tracks to stop the train.
Back in the olden days there were circuits typically called "Hi Fi"
lighting. A high frequency AC feed to the rails powered lights. The motors
were filtered to not see that AC feed. The Hi Fi was constant so lights
were always on.
It would also drive furry animals out of the house if it wasn't tuned
| Of course, with DCC power, what you describe is SOP.
Much has changed.