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previous: MBSetzer Remember when light bulbs used to l... -- 1/25/2001 3:40 PM

Re: Lightbulbs(testing the limits of "Open" forum)

1/25/2001 5:37 PM
Doc	Re: Lightbulbs(testing the limits of "Open" forum) Another thing I noticed relates to the bulb's mechanical construction. Old general purpose bulbs always had extra filament supports. Now, you have to pay more for a super heavy duty industrial grade to get bulbs with minimal filament supports. The properly supported filament is mandatory for use in drop lamps that mechanics use, but you'd be surprised how much vibration gets transmitted into home lamp fixtures from walking across the floor, etc. Another thing which probably helps light bulbs burn out faster (but I haven't proven it) is the poor control over tungsten wire purity, external finish, and cross sectional area. The filament has local weak spots just waiting for a bit of overstress to cause a failure. I tend to agree that the internal atmosphere inside present day bulbs is probably less than inert. The bulb is supposed to be evacuated, then filled with a mixture of argon & nitrogen under low pressure. If the evacuation process is compromised to reduce production time or for built in obsolescence, you get short life bulbs. What's all that black smoke deposited on the glass? I don't remember it being so prevalent on failed bulbs years ago. Another interesting point: R.G. had posted some information about incandescent filaments, how their temperature rises exponentially with small percentages of voltage increase, and mentioned how the bulb's useful life goes down drastically for a few volts above rating. My normal line voltage is now 124vac. I can buy 120v bulbs which are name brand but burn out quickly, or I can sometimes find 130v bulbs in discount stores made in some 3rd world country that don't put out much light and don't last much longer because their build quality is low.

1/25/2001 5:37 PM

Doc

Re: Lightbulbs(testing the limits of "Open" forum)

Another thing I noticed relates to the bulb's mechanical construction. Old general purpose bulbs always had extra filament supports. Now, you have to pay more for a super heavy duty industrial grade to get bulbs with minimal filament supports. The properly supported filament is mandatory for use in drop lamps that mechanics use, but you'd be surprised how much vibration gets transmitted into home lamp fixtures from walking across the floor, etc.

Another thing which probably helps light bulbs burn out faster (but I haven't proven it) is the poor control over tungsten wire purity, external finish, and cross sectional area. The filament has local weak spots just waiting for a bit of overstress to cause a failure.

I tend to agree that the internal atmosphere inside present day bulbs is probably less than inert. The bulb is supposed to be evacuated, then filled with a mixture of argon & nitrogen under low pressure. If the evacuation process is compromised to reduce production time or for built in obsolescence, you get short life bulbs. What's all that black smoke deposited on the glass? I don't remember it being so prevalent on failed bulbs years ago.

Another interesting point: R.G. had posted some information about incandescent filaments, how their temperature rises exponentially with small percentages of voltage increase, and mentioned how the bulb's useful life goes down drastically for a few volts above rating. My normal line voltage is now 124vac. I can buy 120v bulbs which are name brand but burn out quickly, or I can sometimes find 130v bulbs in discount stores made in some 3rd world country that don't put out much light and don't last much longer because their build quality is low.

Replies:

MBSetzer Yup Doc, the *extra* filament suppo... -- 1/26/2001 3:33 AM