Manufacturer: Thorn EMI Lighting Limited
Model: Low Voltage Display Lamp 12v 50w
Application: Display Lighting
Wattage: 50W
Diameter (max): 65mm
Length: 85mm
Tube Length: N/A
Bulb/Tube material: Clear glass, smooth aluminised reflector
Colour Temperature: Approx 3000K
Peak output wavelength: Broadband Emission
Total light output: Unknown
Rated lifetime: Unknown
Cap: E27
Operating voltage: 12V
Operating current: 4.17A (Calculated)
Warmup/restrike time: None
Cost (original): Unknown
Value (now): Unknown
Place of manufacture: Great Britain
Date of manufacture: Unknown - Code B4M Present on cap
Lamp Status: Working

At first glance, not a particularly unusual lamp.  Until you look a bit closer anyway.  Instead of a long mains voltage C shaped filament, there's a tightly coiled 12V filament mounted above a small heat reflective disc.

The downside of the filament being mounted in this way is that combined with the smooth mirror-like reflector, is a very blotchy beam pattern compared to what it would be possible to create using an axial filament.

Also of interest in this lamp is the method that the filament is actually fastened to the support posts, in that rather than the usual crimp arrangement, the filament has actually been welded to the posts, as is the metal disc, being connected to one of the electrical connections to the filament.  This must have been quite an expensive and time consuming assembly to put together compared to more conventional lamp structures.

Another point which makes me think this must be one of Thorn's slightly more upmarket lamps is the highly elaborate cardboard cradle which the lamp is packed in within its carton.


Click Thumbnails for full size images.






This lamp added to the Virtual Display Shelf on the 25th September 2007 at 21:34.

References: None.

Acknowledgements: Many thanks to the website reader who donated this lamp (amongst many, many others) for display.


26th January 2021: Minor changes to page formatting to improve readability on mobile devices.

28th April 2023: Revised Statcounter code to allow for HTTPS operation.

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