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Old January 14th 19, 08:12 AM posted to uk.d-i-y
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Default What's this lightbulb?

I bought a lightbulb (and a ceramic holder and rotary lightswitch) in a
second-hand shop yesterday. They had many beautiful items taken from an
old electronics teaching laboratory - all brass, steel, ceramic and
wood.

The lightbulb:
https://www.dropbox.com/s/qw0vnqdtvemf0ld/lightbulb.jpg?dl=0.

It's about 10cm tall, and has an Edison screw. The filament loops up and
down the bulb in six lengths. It's made by Osram, but there are o other
readable markings on it.

Any idea what the purpose of a lightbulb like this might be?

I'm tempted to run it at low voltage to see what it looks like
illuminated, but I'd hate to damage the filament.

Daniele

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Old January 14th 19, 08:19 AM posted to uk.d-i-y
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Default What's this lightbulb?

On Monday, 14 January 2019 07:12:58 UTC, D.M. Procida wrote:
I bought a lightbulb (and a ceramic holder and rotary lightswitch) in a
second-hand shop yesterday. They had many beautiful items taken from an
old electronics teaching laboratory - all brass, steel, ceramic and
wood.

The lightbulb:
https://www.dropbox.com/s/qw0vnqdtvemf0ld/lightbulb.jpg?dl=0.

It's about 10cm tall, and has an Edison screw. The filament loops up and
down the bulb in six lengths. It's made by Osram, but there are o other
readable markings on it.

Any idea what the purpose of a lightbulb like this might be?

I'm tempted to run it at low voltage to see what it looks like
illuminated, but I'd hate to damage the filament.

Daniele


It's just old. Intended to go in a floodlight.
In days of yore they couldn't make reliable thin tungsten filaments so they had to be long.
It IS interesting.
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Old January 14th 19, 08:45 AM posted to uk.d-i-y
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Default What's this lightbulb?

On 14/01/2019 07:12, D.M. Procida wrote:
I bought a lightbulb (and a ceramic holder and rotary lightswitch) in a
second-hand shop yesterday. They had many beautiful items taken from an
old electronics teaching laboratory - all brass, steel, ceramic and
wood.

The lightbulb:
https://www.dropbox.com/s/qw0vnqdtvemf0ld/lightbulb.jpg?dl=0.

It's about 10cm tall, and has an Edison screw. The filament loops up and
down the bulb in six lengths. It's made by Osram, but there are o other
readable markings on it.

Any idea what the purpose of a lightbulb like this might be?


"Let There Be Light"

Looks to be an old cylinder filament bulb - c.f. modern versions such as

https://www.hollowaysofludlow.com/sh..._filament_bulb


I'm tempted to run it at low voltage to see what it looks like
illuminated, but I'd hate to damage the filament.



--
Robin
reply-to address is (intended to be) valid
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Old January 14th 19, 10:12 AM posted to uk.d-i-y
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Default What's this lightbulb?

In article ,
(D.M. Procida) writes:
I bought a lightbulb (and a ceramic holder and rotary lightswitch) in a
second-hand shop yesterday. They had many beautiful items taken from an
old electronics teaching laboratory - all brass, steel, ceramic and
wood.

The lightbulb:
https://www.dropbox.com/s/qw0vnqdtvemf0ld/lightbulb.jpg?dl=0.

It's about 10cm tall, and has an Edison screw. The filament loops up and
down the bulb in six lengths. It's made by Osram, but there are o other
readable markings on it.

Any idea what the purpose of a lightbulb like this might be?

I'm tempted to run it at low voltage to see what it looks like
illuminated, but I'd hate to damage the filament.


It was a standard physics laboratory supplies lamp, used to make
an image of the filament in things like pin-hole viewers/cameras.

It might not be mains voltage. If it's an uncoiled filament, it
isn't long enough. If it's a single coiled filament, it might be.

Measure the filament resistance with a test meter.
V^2/(resistance * 15) will give you the approx power rating
assuming a tungsten filament. (The times 15 is to correct for the
temperature change when running, although it may be too high a
factor for such a stretched filament lamp.)

It is sort of mimicing the original squirrel cage filament lamps,
but those were far too fragile to be used in a lab where they
would likely be moved around.

The other type of lamp used for this were carbon filament lamps,
but the filament in yours is far too long and floppy to be a
carbon filament lamp. (They are usually 2 - 4 loops, unsupported.)

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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Old January 14th 19, 10:22 AM posted to uk.d-i-y
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Default What's this lightbulb?

Even today they don't make reliable filaments either, long or not. I have a
couple of display cabinets with the filament strip lights behind a baton.
although the filaments are supported every inch or so along the tube they
used to fail very fast. I now run two in series which I'm told gives off a
nice golden light which makes the crystal sparkle better.
Brian

--
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Blind user, so no pictures please
Note this Signature is meaningless.!
"harry" wrote in message
...
On Monday, 14 January 2019 07:12:58 UTC, D.M. Procida wrote:
I bought a lightbulb (and a ceramic holder and rotary lightswitch) in a
second-hand shop yesterday. They had many beautiful items taken from an
old electronics teaching laboratory - all brass, steel, ceramic and
wood.

The lightbulb:
https://www.dropbox.com/s/qw0vnqdtvemf0ld/lightbulb.jpg?dl=0.

It's about 10cm tall, and has an Edison screw. The filament loops up and
down the bulb in six lengths. It's made by Osram, but there are o other
readable markings on it.

Any idea what the purpose of a lightbulb like this might be?

I'm tempted to run it at low voltage to see what it looks like
illuminated, but I'd hate to damage the filament.

Daniele


It's just old. Intended to go in a floodlight.
In days of yore they couldn't make reliable thin tungsten filaments so
they had to be long.
It IS interesting.





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Old January 14th 19, 10:31 AM posted to uk.d-i-y
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Posts: 500
Default What's this lightbulb?

harry wrote:

On Monday, 14 January 2019 07:12:58 UTC, D.M. Procida wrote:
I bought a lightbulb (and a ceramic holder and rotary lightswitch) in a
second-hand shop yesterday. They had many beautiful items taken from an
old electronics teaching laboratory - all brass, steel, ceramic and
wood.

The lightbulb:
https://www.dropbox.com/s/qw0vnqdtvemf0ld/lightbulb.jpg?dl=0.

It's about 10cm tall, and has an Edison screw. The filament loops up and
down the bulb in six lengths. It's made by Osram, but there are o other
readable markings on it.

Any idea what the purpose of a lightbulb like this might be?

I'm tempted to run it at low voltage to see what it looks like
illuminated, but I'd hate to damage the filament.


It's just old. Intended to go in a floodlight. n days of yore they
Icouldn't make reliable thin tungsten filaments so they had to be long.
It IS interesting.


So likely to be a high-powered, standard mains voltage bulb?

I assume it would not come to any harm run at a lower voltage, though I
know that some lamps can darken as the result of deposits on the inside
of the glass when run dimmed.

Daniele
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Old January 14th 19, 10:33 AM posted to uk.d-i-y
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Default What's this lightbulb?

On 14/01/2019 09:12, Andrew Gabriel wrote:
In article ,
(D.M. Procida) writes:
I bought a lightbulb (and a ceramic holder and rotary lightswitch) in a
second-hand shop yesterday. They had many beautiful items taken from an
old electronics teaching laboratory - all brass, steel, ceramic and
wood.

The lightbulb:
https://www.dropbox.com/s/qw0vnqdtvemf0ld/lightbulb.jpg?dl=0.

It's about 10cm tall, and has an Edison screw. The filament loops up and
down the bulb in six lengths. It's made by Osram, but there are o other
readable markings on it.

Any idea what the purpose of a lightbulb like this might be?

I'm tempted to run it at low voltage to see what it looks like
illuminated, but I'd hate to damage the filament.


It was a standard physics laboratory supplies lamp, used to make
an image of the filament in things like pin-hole viewers/cameras.

It might not be mains voltage. If it's an uncoiled filament, it
isn't long enough. If it's a single coiled filament, it might be.


I thought hairpin style filaments weren't coiled - hence the tubular
design (up to at least 8 inches long IIRC) to make them long enough.


Measure the filament resistance with a test meter.
V^2/(resistance * 15) will give you the approx power rating
assuming a tungsten filament. (The times 15 is to correct for the
temperature change when running, although it may be too high a
factor for such a stretched filament lamp.)

It is sort of mimicing the original squirrel cage filament lamps,
but those were far too fragile to be used in a lab where they
would likely be moved around.

The other type of lamp used for this were carbon filament lamps,
but the filament in yours is far too long and floppy to be a
carbon filament lamp. (They are usually 2 - 4 loops, unsupported.)



--
Robin
reply-to address is (intended to be) valid
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Old January 14th 19, 10:45 AM posted to uk.d-i-y
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Posts: 320
Default What's this lightbulb?

On 14/01/2019 09:31, D.M. Procida wrote:

snip

So likely to be a high-powered, standard mains voltage bulb?


If it is mains, there probably wasn't a 'standard' supply voltage when
it was made.

I assume it would not come to any harm run at a lower voltage, though I
know that some lamps can darken as the result of deposits on the inside
of the glass when run dimmed.

Daniele


Cheers
--
Clive
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