View Full Version : OT: light bulb

08-01-2006, 01:35 AM
Okay, how has this light bulb been running 105 years?



08-01-2006, 01:47 AM
OK, maybe 3 things.....
a) Might be an exagerration of it's age. However I don't understand how the evacuation or gas fill (argon or ?) could last that long, unless it was very good.
b) Contributing factors might be a very heavy tungsten filament and a low operating voltage. (Eg. the old outdoor rural lighting trick of using 240 V rated lamps on 120 V; not very bright, but they last a looong time.)
c) Low thermal stresses due to never or rarely ever being turned off ?

Just my random thoughts.

08-01-2006, 02:49 AM
That's an old Edison bulb. He used a carbon filament in a vacuum. It will last as long as the vacuum does. Carbon doesn't outgas atoms like tungsten does. My dad had a set of edison bulb christmas lights, big hand blown bulbs. They had been handed down from his father and were many years old, complete with braided cloth insulation on the wires. They all worked. They aren't very bright.

Doc Nickel
08-01-2006, 05:18 AM
If the age has been exaggerated, it's only by a year or two.

As Evan noted, it's probably a carbon filament, and obviously run at fairly low power. If you run a modern bulb at low power, they last an astonishingly long time. I suspect it's also run on DC. The bulb is undoubtedly considerably thicker glass than modern bulbs, and the filament probably quite a bit coarser.

Last, note that while it does say "continuously", they acknowledge that it's been out with various power failures over the years, as well as being moved three times.


08-01-2006, 10:54 AM
Another interesting item to add re light bulbs. In my dealing with CSA (Canadian Standards Association) on approving various Klixon thermostats, one of the tests was for an incandescent rating. The inrush current is about 9x rated for a split second and naturally the test at CSA involved the use of banks of light bulbs ranging from huge to ones we buy (used to) for household use.

The bulbs at the test house were being continuously switched on and off (about 6x a minute) by the action of the thermostat being tested. I once went to the test room to verify that the setup was correct for a particular approval and was amazed at the huge array of bulbs on the wall mounted rig. I mentioned to the technician there that he must have a full time job changing bulbs. He replied that he had not replaced one in over 20 years! He figured that the short on-time (about 3-4 seconds) never allowed the bulbs to get really hot. So I learned something that day.



08-01-2006, 11:12 AM
The Henry Ford Museum has quite a display of lightbulb making, including an automated lightbulb glass blowing machine.

They could make bulbs that lasted forever then, and I have no doubt they can now. The only problem is that they would only sell one per application, while now they sell one every thousand hours of use in that application.

08-01-2006, 11:57 AM
We can make bulbs that last forever now, no problem. It helps to like deep yellow to red light.

Frank Ford
08-01-2006, 12:22 PM
Sure - it's no problem to make light bulbs last - just drop the voltage. I have some exterior floods (just standard bulbs) that have been working nightly since 1980. There are six mounted on the parapet wall of my house, and none has burned out. All I did was put a dimmer in line with them. Same for the sconces in my hallway. They are cheap candelabra bulbs, but they've been online for 15 years with the same arrangement.

I don't like changing bulbs, so for years I've used 130 volt standard bulbs in lamps and fixtures. McMaster has 'em, along with everything else.

Lately, I've been switching over to those twisty fluorescent replacements where I want good light and less heat. Speaking of "good" light, take a look a the three way bulb switch on my favorite old (1940s) floor lamp:


08-02-2006, 02:45 PM
Connect 2 bulbs in series and each will get only 1/2 the voltage and should last close to eternity. For many bulbs at 1/2 power, put a large diode in one of the line wires. The diode will only let 1/2 of the ac wave through thus running the lights at 1/2 power.

Optics Curmudgeon
08-02-2006, 03:06 PM
You can buy a button like device that you put in the bottom of the socket that has a diode in it, just for that purpose. I've visited the bulb in question (It's in the city where I live), it's only a 3 or 4 watt carbon filament bulb, glowing relatively faintly. It even looks like it would burn forever. Other than Max Baer, it's the only famous thing we can claim. Oh, and Randy Johnson, almost forgot.

08-02-2006, 04:11 PM
Heh. I grew up halfway between Danville and Walnut Creek. I don't think I ever actually went to Livermore for anything except just driving through. The only thing of interest to me there is the Lawrence National Lab and I don't have a clearance for that one. My dad does (or used to).

Your Old Dog
08-02-2006, 08:02 PM
They'll last much longer if they're not turned on and off. I've noticed the dramatic change in bulb life since I've added several variable/slider type switches to hallway, bathroom and dining room lights. One bathroom in the older house the 8 bulbs on the vanity lasted over 4 years and never needed replaced.

There is a firehouse in buffalo new york with an outside bulb similar to the one pictured. They also claim it's been on some ridicules amount of time but it's never turned off.

Paul Alciatore
08-03-2006, 01:41 AM
Yes, we can and do make long life bulbs. As stated above, they are simply designed for a lower light output by using a heavier filament. This is exactly the same idea as using two bulbs in series so that each one has only half voltage across it since the heavier filament would glow at full brightness at a higher voltage. And they can last 2, 3, 5, or more times as long as standard bulbs. But the light is very red and a bulb of equal Wattage would make even more heat than a standard bulb. They have been advertised as money savers because of their long life, but in reality they are more expensive to operate for the same amount of light produced because more bulbs or higher Wattage bulbs are needed.

The truth of the matter is that the standard bulb is optimized for the greatest economy when the cost of the electricity needed to produce a given amount of light is factored into the equation.

If you have several 60 or 100 Watt bulbs in an area that would be OK with less light, it would be more economical to install lower Wattage STANDARD bulbs instead of using equal Wattage long life bulbs. Both would give you less light. But, the lower Wattage standard bulbs will save money in your electric bill and that savings would more than offset the higher price of replacing them (the standard bulbs) several times over the longer life span of the long life bulb.

Sylvania, GE, and the other bulb makers actually do know what they are doing!!!!!

Of course, even the least efficient fluorescent bulb will be more economical than any of the incasadent bulbs. And the high efficiency ones will be far, far more economical. Again, this is for the same amount of light.

The latest long life "bulb" design uses multiple LEDs. The LEDs have a very long life expectancy and can be considered permanent in most applications. But at present they are as expensive as the ****ens and only run on DC. I have saved a lot of time and my company's money by switching to LED versions of the miniature bulbs used in illuminated push button switches. In a TV facility there are hundreds, if not thousands, of these bulbs and they used to be a constant maintenance item. That translates into man hours and dollars. I haven't changed one in over four years now. So they are very economical in this application in spite of their high cost.

Paul A.

A.K. Boomer
08-03-2006, 10:44 AM
Are bulb companies in ka-hoots with the power companies or what,,, how come i have to pay over double the price for 25 watt bulbs as compaired to 60's or 100's?