I'm using one set of Aamsco's Ferrowatt
1910 bulbs in Lynchburg 34 at Branford. They
were cataloged and labeled as 120 Volt, 40
Watt, and twice as much Candle Power per
Watt as anything else they listed. I think
they were listed as 32 c.p., everything else
was 8 or 16. On the phone, I was told that
the high efficiency was due to a tungsten
instead of carbon filament. They were used
to replace real 1910 bulbs that we had
acquired from 3rd Ave. Transit System in 1947.
Some had even been made by a predecessor to
Ferrowatt!

We ordered 12 bulbs for this 11 bulb car.
One didn't survive shipping, the glass filament
support broke.

I ran into a problem - the headlight
fixtures take bulbs mounted base down. They
now have modern reflectors which fit A-19 or
21 or 23 size bulbs (like 36 or 56 Watt Street
Railway interior lights). These big
reproductions won't fit. The antiques we had
in the headlights were slightly smaller, from
a different manufacturer. I removed the
reflectors so the reproductions would fit, but
Superintendent Ted was afraid they would get
lost and had me put them back in. He gave me
a pair of 36 Watt, 120 Volt Street Railway
Headlight (clear) bulbs, which are the same
shape and size as interior bulbs. I put one
in and threw the changeover switch to light it.
The rest of the lights in that string burned
brighter than they had when in series with one
of themselves in the other headlight. I
expected them to bun slightly dimmer when put
in series with a bulb of slightly less wattage
and therefore higher resistance. Obviously,
these reproductions must have higher resistance
and therefore less Wattage than a 36 Watt bulb.
Tolbert Prowell of RTY later confirmed by
testing that these are really 30 Watt, 120 Volt
bulbs, and that in an order of 12, one won't
survive shipping. Later, I found a pair of 130
Volt, 36 Watt Street Railway Headlight bulbs
which burn at about 33.23 Watts on 120 Volts,
and are a slightly better match. The car does
look nice and bright all lit up! However, it
has not yet been moved.

Recently, I bought the 1st 14 of the new
60 Watt, 130 Volt, Rough Service 1910
Reproduction bulbs, made in a Swiss watch
factory, to install in Third Ave. Rwy. ex
cable car 220. (It still had some of the bulbs,
or spares for them, that came with the car in
1947. They might even have been installed when
the cable car's gas lights were removed. Since
the car uses 6 bulbs to a string, they last
forever!) The new ones have the same size
problems as the regular reproductions. Since,
on 120 Volts, these should draw about
55.38 Watts, I tried a brand new 56 Watt, 120
Volt Street Railway Headlight (clear) bulb just
bought from Aamsco. (These are P-27 headlight
size and shape, larger than interior trolley
bulbs.) The filament burned orange! Even a
36 Watt, 120 Volt Street Railway bulb burnt dim.
These new things look very nice, and all of them
survived shipping, but they must be 25 or 30
Watts! Aamsco says they will send some to Tod
Prowell for testing, and if not as ordered, will
have the manufacturer make new ones properly!

Does anyone want to compare experiences
with Brooklyn Rapid Transit semi-convertable
trolleys and their weird headlight circuit?

How about 3rd Ave. lightweight homemade
cars and their door and step interlocks?
(629, 631, 678, etc.)

These could be separate threads.


104577.651@compuserve.com

Just a few comments and tech notes:

> I'm using one set of Aamsco's Ferrowatt
> 1910 bulbs in Lynchburg 34 at Branford. They
> were cataloged and labeled as 120 Volt, 40
> Watt, and twice as much Candle Power per
> Watt as anything else they listed. I think
> they were listed as 32 c.p., everything else
> was 8 or 16. On the phone, I was told that
> the high efficiency was due to a tungsten
> instead of carbon filament.

Dr. Coolidge (Nela Park) perfected drawing tungsten around 1913-14, therefore, there were no tungsten bulbs before this. Carbon filaments were typically rated in CP, tungsten in lumens.

> I ran into a problem - the headlight
> fixtures take bulbs mounted base down. They
> now have modern reflectors which fit A-19 or
> 21 or 23 size bulbs (like 36 or 56 Watt
> Street
> Railway interior lights).

A-19 and A-21 are standard headlight sizes, until you start looking at 101 and 250 watt lamps.

> He gave me
> a pair of 36 Watt, 120 Volt Street Railway
> Headlight (clear) bulbs, which are the same
> shape and size as interior bulbs.

These and their 56 watt counterparts have the filament abnormally close to the base so they can be focused in the ESSCo Golden Glow refectors.

>I put one
> in and threw the changeover switch to light
> it.
> The rest of the lights in that string burned
> brighter than they had when in series with
> one
> of themselves in the other headlight. I
> expected them to bun slightly dimmer when
> put
> in series with a bulb of slightly less
> wattage
> and therefore higher resistance.

If there are four interior lamps in series with the headlight, the headlight lamp must be of equal wattage to those in the rest of the series. If there are eight interior lamps, then the healight must be double the wattage.

>Obviously,
> these reproductions must have higher
> resistance
> and therefore less Wattage than a 36 Watt
> bulb.
> Tolbert Prowell of RTY later confirmed by
> testing that these are really 30 Watt, 120
> Volt
> bulbs, and that in an order of 12, one won't
> survive shipping. Later, I found a pair of
> 130
> Volt, 36 Watt Street Railway Headlight bulbs
> which burn at about 33.23 Watts on 120
> Volts,
> and are a slightly better match. The car
> does
> look nice and bright all lit up! However, it
> has not yet been moved.

Try a Philips 30A15/CL 130V (product code 30452-7), which is a 30 W, A-15 bulb. If you need an A-19 envelope, try a Sylvainia 32A19/49 120V (code 10980), which is 32 W. Both of these are clear class C sign lamps, have C-9 filaments, and are rated for 3000 hours.

> Recently, I bought the 1st 14 of the new
> 60 Watt, 130 Volt, Rough Service 1910
> Reproduction bulbs, made in a Swiss watch
> factory, to install in Third Ave. Rwy. ex
> cable car 220. (It still had some of the
> bulbs,
> or spares for them, that came with the car
> in
> 1947. They might even have been installed
> when
> the cable car's gas lights were removed.
> Since
> the car uses 6 bulbs to a string, they last
> forever!) The new ones have the same size
> problems as the regular reproductions.
> Since,
> on 120 Volts, these should draw about
> 55.38 Watts, I tried a brand new 56 Watt,
> 120
> Volt Street Railway Headlight (clear) bulb
> just
> bought from Aamsco. (These are P-27
> headlight
> size and shape, larger than interior trolley
> bulbs.) The filament burned orange! Even a
> 36 Watt, 120 Volt Street Railway bulb burnt
> dim.
> These new things look very nice, and all of
> them
> survived shipping, but they must be 25 or 30
> Watts!

Have you measured one with an ohmmeter?

>Aamsco says they will send some to
> Tod
> Prowell for testing, and if not as ordered,
> will
> have the manufacturer make new ones
> properly!

Don't use lamps with C-17A filaments, in a 600V DC series, they fail almost immediately.

> Have you measured one with an ohmmeter?

How can one measure the lamp's wattage
with an ohm meter? The only true test is
to apply the rated voltage and measure the
current. The cold filament resistance
is much lower than the operating resistance.

webmaster@bera.org

> How can one measure the lamp's wattage
> with an ohm meter? The only true test is
> to apply the rated voltage and measure the
> current. The cold filament resistance
> is much lower than the operating resistance.

It depends on what you're trying to do. Without special equipment, it's a lot easier to measure the cold resistance than the illumination current, particularly in the field.

The thing to do is to build up a database of cold resistances for known lamp wattages. Then if you're trying to identify a lamp which has lost its makings, all you have to do is measure its cold resistance. It does get a little complicated if you're dealing with lamps of different voltages.

On the other hand, if you're trying figure out how to mix carbon and tungsten, then you would have to match the current drawn by the carbon lamp to the tungsten one (and vice versa).

FWIW, I measured a 75W 120V IF house lamp, and found the ratio of hot res/cold res to be about 15/1 (186 ohms hot/12.5 cold). A 36W 120V RYH lamp has a ratio of 5/1 (343 ohms/28 ohms).

Unfortunately, the best manufacturer of carbon lamps, NALCO of St. Louis, went out of business around 1980. They had been in business for decades and had excellent quality control. Even at the end they carried an S-21 32CP 120V lamp.

BTW:
A carbon filament lamp gives a yellower light then that of a tungsten lamp. A carbon filament lamp is close to a kerosene flame, giving a true green color to your "blue-green" marker lenses.

lamontdc@adelphia.net

2 questions for Pete and the rest of you:
> A-19 and A-21 are standard headlight sizes,
> until you start looking at 101 and 250 watt
> lamps.
> These and their 56 watt counterparts have
> the filament abnormally close to the base so
> they can be focused in the ESSCo Golden Glow
> refectors.
Are 56 Watt Street Railway Headlights the same
shape as the 56 and 36 Watt Street Railway
interior bulbs and 36 Watt Street Railway
Headlights? The 56 Watt 120 Volt Headlight bulbs
I just bought from Aamsco were cataloged as
Street Railway, but shaped like Locomotive
Headlights, perhaps P-27. (The invoice was also
written "Locomotive Headlight", but Amsco said
that was a database error.")

> Try a Philips 30A15/CL 130V (product code
> 30452-7), which is a 30 W, A-15 bulb. If you
> need an A-19 envelope, try a Sylvainia
> 32A19/49 120V (code 10980), which is 32 W.
> Both of these are clear class C sign lamps,
> have C-9 filaments, and are rated for 3000
> hours.
Tod Prowell of RTY has publicized the industry
and manufacturer's explainations of why Class C
(gas filled) bulbs must be shorting or "Arc
Resist" when used on 600 Volt D.C. Otherwise,
a Class B (Vacuum) bulb should be used.
The bulbs I bought from Aamsco were supposed
to be Class B.


104577.651@compuserve.com

> 2 questions for Pete and the rest of you:
> Are 56 Watt Street Railway Headlights the
> same
> shape as the 56 and 36 Watt Street Railway
> interior bulbs and 36 Watt Street Railway
> Headlights?

The 36 watt ones, yes. The 56s are slightly larger than an IF 56W bulb. BTW, "A" stands for "arbitrary".

>The 56 Watt 120 Volt Headlight
> bulbs
> I just bought from Aamsco were cataloged as
> Street Railway, but shaped like Locomotive
> Headlights, perhaps P-27.

56RYH bulbs look like more pear shaped or globular that A shaped. Not sure what P stands for, but "PS" is "pear shaped", "G" is "globular", "S" is "straight" [sided], "T" is "tubular", and "R" is "reflectorized"

> (The invoice was also
> written "Locomotive Headlight",
> but Amsco said
> that was a database error.")

Not if they are clear and have a C-5 filament down in the lower quarter of the bulb by the base. These used to be sold under the designation of 56A21RYH. If the bulb is clear and the filament is a C-9 up in the same location as a frosted 56 watt bulb, then it is a database error.

> Tod Prowell of RTY has publicized the
> industry
> and manufacturer's explainations of why
> Class C
> (gas filled) bulbs must be shorting or
> "Arc
> Resist" when used on 600 Volt D.C.
> Otherwise,
> a Class B (Vacuum) bulb should be used.
> The bulbs I bought from Aamsco were supposed
> to be Class B.

Break one and see if there is a loud pop when compared to breaking a standard house lamp. An evacuated bulb will have a pronounced pop.

The explosions caused by class "C" bulbs burning out on DC was mainly a result of the early practise of using nitrogen to fill the bulb. Modern C bulbs use mixtures of inert gases like argon and aren't as prone to exploding (or blackening). My Osram catalogue (unfortunately 9 years old) lists 56 and 36 watt lamps as being type B. I've used C types in 600 volt series over the years and not had many problems with them exploding. However "arc resisting" helps, and you should never leave an artifact (streetcar, interurban, etc.) sit unattended with the lights. I have seen 36W, 56W, and 1.6A30V bulbs explode many times.

BTW, a Philps 33A19/GR/CL 130V bulb is an type B bulb with a C-9 filament.

> Without special equipment, it's a lot easier
> to measure the cold resistance than the
> illumination current, particularly in the
> field.

OK, admittedly if one is literally "in the field"
with just a handheld DMM, cold resistance is
the only option.

> FWIW, I measured a 75W 120V IF house lamp,
> and found the ratio of hot res/cold res to
> be about 15/1 (186 ohms hot/12.5 cold). A
> 36W 120V RYH lamp has a ratio of 5/1 (343
> ohms/28 ohms).

The V^2/R on the former works out to 77W, pretty
close, but the latter 41W. How are these bulbs
characterized? Isn't the wattage current times
voltage at the rated voltage?

Here's an even more obscure question posed once
by Mr. Boylan, for which I don't have a good
solution: How can one determine, without
destroying it, the rating of an umarked fuse?



webmaster@bera.org

> OK, admittedly if one is literally "in
> the field"
> with just a handheld DMM, cold resistance is
> the only option.

> The V^2/R on the former works out to 77W,
> pretty
> close, but the latter 41W. How are these
> bulbs
> characterized?

The 75 watt bulb has a life of 800 hours, the 36, 2000. This means there is less demand on the filament, so if you were to burn it (the 36 watt bulb) at the same lumens per unit of filament area as the 75 watt one, it probaly works out to being the equivalent of a 41 watt bulb. It would also shorten the bulb life to 800 hours.

The light oubput of any bulb is a balance between life and output (brightness). The longer the life, the dimmer the bulb. A 120 volt photoflood bulb is more or less a 90 volt bulb used on 120 volts (this is a bit of simplification).

Tha famous bulb at the firehouse (Hayward, CA?) which has been "burning for 100 years" is just a 250 or 300 volt bulb being used on 120 volts. It will burn out eventually, and it doesn't give much light. A typical use for 220 volt bulbs on 110 volts is illuminated exit signs, places where you need to see the bulb and not what it illuminates.

> Isn't the wattage current
> times
> voltage at the rated voltage?

P=EI, yes. P=power in watts, E=pressure in volts, I=current in amps.

> Here's an even more obscure question posed
> once
> by Mr. Boylan, for which I don't have a good
> solution: How can one determine, without
> destroying it, the rating of an umarked
> fuse?

What kind of fuse? If you can get to the fuse wire with a set of vernier calipers, it's easy.

> The light oubput of any bulb is a balance
> between life and output (brightness).
> A typical use for 220 volt bulbs on 110
> volts is illuminated exit signs.
I just bought tubular fire exit sign bulbs
for the Railroad Office Building. They are
labeled 145 Volts!

> What kind of fuse? If you can get to the
> fuse wire with a set of vernier calipers,
"Cartridge", metal caps crimped on a
"cardboard" tube. I guess I sacrifice one
to see what's inside.

104577.651@compuserve.com