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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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8th May 2011, 9:10 pm | #41 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
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Re: Pip top bulbs and adulterations etc ?
Amazing! One thing is for sure. You think you have seen everything in the electrical trade and then somebody plops a twin filament light bulb on the counter.. J.
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9th May 2011, 11:51 am | #42 |
Nonode
Join Date: May 2006
Location: St Albans, Herts, UK.
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Re: Pip top bulbs and adulterations etc ?
What an interesting lamp! Great selling point eh?
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9th May 2011, 3:00 pm | #43 |
Pentode
Join Date: Feb 2008
Location: Belfast, Northern Ireland, UK.
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Re: Pip top bulbs and adulterations etc ?
Yes the Light bulb with two lives
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9th May 2011, 4:15 pm | #44 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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Re: Pip top bulbs and adulterations etc ?
Presumably these dual filament bulbs would have required a special holder, though? A standard light bulb base has 2nd order spin symmetry ..... i.e., if you turn the bulb through 180°, the contacts end up in exactly the same places. Any long-term saving on lamps would be swallowed up by the extra up-front cost of the special holders, not to mention the uncertainty associated with a product only being available from a single supplier.
I do know that Edison made dual filament bulbs with a base on each end, which led to the discovery of thermionic emission .....
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9th May 2011, 4:36 pm | #45 |
Pentode
Join Date: Feb 2008
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Re: Pip top bulbs and adulterations etc ?
This bulb is in a standard socket it has a mechanism on the base and three contacts the bulb when turned round clicks into place. As you can see in the pics the two seperate pieces of the base.
Scott |
9th May 2011, 5:26 pm | #46 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
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Re: Pip top bulbs and adulterations etc ?
Unbelievable!
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9th May 2011, 5:35 pm | #47 |
Dekatron
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Re: Pip top bulbs and adulterations etc ?
I too was wondering how it dealt with the rotational symmetry of a BC fitting. Now I understand - that the bulb rotates with respect to the locating lugs.
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9th May 2011, 7:57 pm | #48 |
Pentode
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Location: London, UK.
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Re: Pip top bulbs and adulterations etc ?
As I understand it, it was (is?) quite common in the USA to have a dual filament lamp, with an ES base having concentric contacts. The filaments would be of 2 different sizes, and the lampholder would have switching to select one or the other or both to allow 3 different output levels. This was quite common on USA standard or table lapms before compact electronic dimmers were widely available, I have no idea if they are still common, perhaps someone 'across the pond' could errr.... enlighten (sorry) us?
Also, I recall some Strand TV studio lanterns we had at college being fitted with twin filament 4 pin halogen lamps and switchgear so that the output could be reduced without the colour temperaure being affected, rather than using a dimmer which would lower the colour temperature as well as the light output.
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"Broken we can fix, cr*p is a design issue" Last edited by robin0577; 9th May 2011 at 8:06 pm. Reason: Addition |
10th May 2011, 10:32 am | #49 |
Octode
Join Date: Sep 2005
Location: Welshpool, Powys, Wales
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Re: Pip top bulbs and adulterations etc ?
That is pretty amazing
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10th May 2011, 8:16 pm | #50 |
Dekatron
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Location: Warnham, West Sussex. 10 miles south of DORKING.
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Re: Pip top bulbs and adulterations etc ?
Philips produced a lamp with two filaments 100w + 60w in the 60's with a special adaptor.
I have one somewhere. This gave either 60W, 100w or 160w. I'll have a search later in the week. J. |
11th May 2011, 9:49 am | #51 | |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
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Re: Pip top bulbs and adulterations etc ?
Quote:
The other reason that this lamp type is favoured, is that the light output is equal in all directions around the horizon. Some modern compact filaments are suprisingly directional, giving a lot more light in some directions than others. Another reason is that older navigation lamps would have used an oil flame, not an electric lamp. The large filament is of a somwhat similar size to an oil flame and should therefore work better in fittings designed for oil. |
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11th May 2011, 2:08 pm | #52 | |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
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Re: Pip top bulbs and adulterations etc ?
Quote:
Sometimes otherwise standard lamps had a 3 pin base to discourage theft. Some low voltage twin filament lamps have a 3 pin base, these are still used today for railway signaling. 12 volt, one 16 watt filament and one 24 watt filament. The metal shell of the lamp cap was the common connection, with each filament being connected to one of the solder pads. 3 pin bayonet lamp caps are still used today, MEM make a CFL with a 3 pin BC base. This prevents standard incandescent lamps being used. |
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11th May 2011, 2:10 pm | #53 |
Moderator
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Re: Pip top bulbs and adulterations etc ?
Some energy saving bulbs have three spigots. This is to prevent normal bulbs being used in the associated bulb holder. New build houses tend to have these.
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12th May 2011, 11:41 am | #54 | |
Tetrode
Join Date: Apr 2003
Location: Wantage, Oxfordshire, UK.
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Re: Pip top bulbs and adulterations etc ?
Quote:
As I recall it even has a little rhyme on the box which goes something like "We are the original DoTwo twins, when one leaves off the other begins" The bulb itself is neither frosted nor clear, instead the glass is of a dimpled pattern, quite unlike anything else I've ever come across. Regards Philip |
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4th Aug 2012, 3:09 pm | #55 |
Pentode
Join Date: Oct 2010
Location: London, UK.
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Re: Pip top bulbs and adulterations etc ?
Not sure if I should have started a new thread for this?
Here's on I found in a backstage storage cupboard in a theatre I was working on a few days back, 240v, 1000w, GES cap. Looks unused but handled. Would have been used in a 1950s theatre floodlight like this http://www.strandarchive.co.uk/lanterns/p49.html http://i937.photobucket.com/albums/a...IvorBiggun.jpg
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4th Aug 2012, 4:38 pm | #56 |
Heptode
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Re: Pip top bulbs and adulterations etc ?
Very nice find there! Used to have a 500W example by Crompton of a similar design, sadly it fell prey to dreaded gravity during a house move - larger lamps like this are always tricker to store safely because of their size and fragility. Theatres seem often to be a treasure trove of old tech like this. One I was in a few years ago (sadly now gone I believe) still had most of the lighting in the lesser travelled (the main bits had been upgraded) by old BC fluorescent fittings. If I remember rightly though the whole place is gone now.
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4th Aug 2012, 5:55 pm | #57 |
Pentode
Join Date: Oct 2010
Location: London, UK.
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Re: Pip top bulbs and adulterations etc ?
They also had several 500w examples of that design, but they still have and still use the floodlights that fit them.
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"Broken we can fix, cr*p is a design issue" |
4th Aug 2012, 7:13 pm | #58 |
Nonode
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
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Re: Pip top bulbs and adulterations etc?
Hi,
I spotted this old bulb when I was viewing a house I was interested in, I've never seen one with the filament arranged like this. Unfortunately I left it there! The house was empty and practically falling down! It did look like a normal bulb on the outside, so it may be a fairly recent one, but I thought I'd put it here to see what others think Regards, Lloyd |
4th Aug 2012, 7:46 pm | #59 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
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Re: Pip top bulbs and adulterations etc?
Definately an old one Lloyd. I used to carry a box of new lamps in the back of my service van. It was incredible how many old bulbs were still in daily use in customers houses. It took only moments to swap them over! John.
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4th Aug 2012, 8:16 pm | #60 |
Dekatron
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Location: Leominster, Herefordshire, UK.
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Re: Pip top bulbs and adulterations etc?
Looks like it was left because it didn't work!
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