Maker's Name: 
Sylvania GTE
Where made: 
3.6 × 3.6 × 8 cm

This is an incandescent lamp for a home or military film projector. The filament probably operates in an atmosphere of iodine vapour to reduce tungsten evaporation, and operates at a temperature very close to melting point, thus increasing brightness, and whiteness.

An interior spherical reflector ensures that radiation off the back of the filament is also used to add to the brightness.

For long life, the filament should be fed with DC 24V rather than AC. Also a series thermistor will allow slow heat-up time, thus increasing the life of the filament and reducing the initial rush-in current when the filament is cold. This can be 5 to 6 times the fully-lit current.