I am not scared of the dark, but I don't like having a bath by candle light after the bulb went. My idea would stop this by having a 24 hour warning flash, prompting the purchase of a new one prior to it running out. Could also annoy my brother. (the flashing thing).-- gizmo, Dec 13 2001 Mentioned in passing. http://www.halfbake...up_20Bulb#996686438I *knew* we'd done some this discussion before. [angel, Dec 14 2001, last modified Oct 04 2004] Backup Filament Light Bulb http://www.halfbake...ment_20Light_20BulbThe idea that appeared as an annotation to 'The Backup Bulb' and 'Blink bulb' distilled as its own idea. [st3f, Dec 15 2001, last modified Oct 04 2004] The Darksucker Conspiracy! http://winn.com/bs/darksuck.htmlThe truth is out there!...WAAY out there... [StarChaser, Dec 16 2001, last modified Oct 04 2004] LED Musueum http://ledmuseum.home.att.netAll manner of LED info [bristolz, Dec 28 2001, last modified Oct 04 2004] Forever Bright™ LED Christmas Lights http://www.foreverbright.com/These'd work . . . If you can ever find them for sale. I looked all over for these in the Seattle area and . . . no luck. [bristolz, Dec 28 2001, last modified Oct 04 2004] how are we going to get this to work giz?-- po, Dec 13 2001 No. I hate it when they flash like that, even if it's just for a few seconds before they go.-- pottedstu, Dec 13 2001 mmmmm....... 24 hours migrane.-- gizmo, Dec 13 2001 Maybe the bulb would just have a spot on it that got dark, say, 20 hours before failure (unless the failure is from physical shock, then all bets are off). Alternatively, it could have a subtle beep. Alternatively, it could unscrew itself and fling itself to the floor. Alternatively, all the lights could be instrumented and networked to a predicted time to failure annunciator mounted on the kitchen wall (or your computer). I don't know exactly what criteria within the bulb would be monitored to estimate a coming failure. Maybe light output begins to either increase or decrease as failure looms and that could be monitored.-- bristolz, Dec 13 2001 po: don't really know exactly, but it usually flashed or goes very bright just before going out, maybe the manufacturers could make this process last a bit longer, or a 24 hour back up bit, powered by batteries, not thought it through properly I know, sorry.-- gizmo, Dec 13 2001 Or all bathroom light fixtures could have two sockets, and you change one of the bulbs when it's only halfway through its life expectancy. Except in the case of physical shock, you only risk a dim bath, not a dark one.-- hello_c, Dec 13 2001 britolZ: you got there first, I like the computer link thing, better than my idea.-- gizmo, Dec 13 2001 We bought two new bulbs for the kitchen (don't think you can but them second hand) and fitted them both at the same time, one went about 3 weeks ago and the other is still going strong - so, "helloC" this might not be a foolproof method, not given reliabiltiy of bulbs and their life span.-- gizmo, Dec 13 2001 speaking lights would be cool, "I'm faadinnnng", "I can't glooww muuch loooonger"-- arora, Dec 13 2001 Riff on hello_c's idea: All bathroom sockets are doubled but only one light is used, upon failure of the primary (first) light an automatic failover to the secondary light takes place.-- bristolz, Dec 13 2001 This idea just won 20 grand didn't it?-- notripe, Dec 13 2001 Bulbs flare just before dying because the filament has broken, and the electricity is arcing. It only lasts as long as the two parts of the filament are close enough together for the arc to work, ie very briefly.
Should think it shouldn't be too difficult to include a high-resistance emergency filament in the things...Electricity takes the path of least resistance; the normal filament would be easier than the emergency, but the emergency would be easier than nothing when the main one breaks.-- StarChaser, Dec 14 2001 ...do people really have bathrooms that only have one light bulb as the light source? odd.....
Why not just keep extra bulbs on hand for a quick replacement?-- Susen, Dec 14 2001 notripe: I haven't seen a penny of it yet!-- gizmo, Dec 14 2001 I think (unless this is baked somewhere) that StarChaser has a genuine, bakeable, saleable idea here.
Light bulbs blow because the filament evaporates (you can see the residue in the dark parches on the inside of an old bulb)
So you construct a light bulb with two filaments. One is made as per normal but the other (made of a material with higher resistivity) is thicker *and* has higher resistance and is mounted in parallel with the first. This ensures that it draws a small current allowing it to glow dimly thus giving you enough light to safely find your way arount the bathroom, but not enough light to read in the bath.
As this filament draws less current it should last longer and still be glowing when the first filament blows. These could be sold as 'critical use' light bulbs for places where there is only one bulb.
<boring_numbers locality="UK" mains_voltage="240"> A 60W light bulb has a resistance of 1000 ohms. It will draw a current of 0.24 amps.
The bulb with a second filament of 10000 ohms resistance will draw 0.26 amps, 0.24 going to the main filament, 0.02 going to the backup filament.
When the main filament blows the backup alone will draw 0.024 amps hopefully (if we've picked our materials and figures correctly) emitting a dim glow. </boring figures>-- st3f, Dec 14 2001 (linky)-- angel, Dec 14 2001 angel: That's for an additional bulb. It's only PotatoStew's annotation that mentions the idea of making bulbs with backup filaments.
Anyone seen of heard of a backup filament in the real world?-- st3f, Dec 14 2001 [st3f]: I agree. Link text modified to say what I meant in the first place.-- angel, Dec 14 2001 Now where did I read about the practice of sending new guys out to the hardware store to buy spare filaments for bulbs?-- neelandan, Dec 14 2001 how often do you have 'new guys' in your bathroom?-- lewisgirl, Dec 14 2001 [st3f] I would be suspicious of that idea's ability to work. Would you be able to find a material that is able to glow, has a higher resistance (remember that filaments have an extremely high resistance already), and will be thicker than your existing filament as well as being able to withstand the temperature. I think that might be asking too much. I may, however be wrong.-- stupop, Dec 14 2001 What if the bulb gave the warning that it was about to die, but when you took it out and put a new one in, you found that there was nothing wrong with it? You might have doubts about the integrity of the warning mechanism - despite the manufacturer's claims that the bulbs are incapable of error - and so you'd put the old one back in until it failed. The bulb could well get mightily annoyed that you doubted it, and lock the bathroom door so that you can't get in there when you need to.
The solution: don't make bulbs that can lipread.-- -alx, Dec 14 2001 Stupop: to save on developing a material for the second filament you could make the it out of a length of the same wire used to make the primary filament and connect a large resistor in series with it to lower the current in that branch.-- st3f, Dec 14 2001 You are talking about filament bulbs, but there are also sodium arc bulbs which don't have a filament. Presumably one could have both in a lightbulb: a tungsten filament which gives white light and is the main source and a backup of sodium which will take over when the filament breaks and gives yellow light. No flashing, just a colour change.-- lubbit, Dec 14 2001 Flourescent* tube lights flicker for hours if not days before they need replacing, as if they're not annoying enough when they're working properly. (Their use is part of a job security measure for maintenance staff -- you can survive with one dead light, but not an evil flicker all day. You need it replaced immediately, no matter what the cost.) Just use flour' tubes instead of filament bulbs, if you don't mind looking even worse than usual in the mirror of a morning.
*In-joke: this used to drive my chemistry teacher insane.-- pottedstu, Dec 14 2001 [lubbit]: You can't use sodium bulbs directly in a domestic application; they need a high-voltage ballast or some such thing, which tend to be daftly expensive.[pottedstu]: I'm with you on fluorescents - I hate the bloody things.-- angel, Dec 14 2001 I don't know about the technical doo-dad stuff, but StarChaser's idea does sound bloody bakeable from a layman's perspective.
Fluorescent lights suck. Far too much light in the blue spectrum, making it feel 'unnatural' and 'cold'.-- Guy Fox, Dec 14 2001 StarChaser: Hey, don't forget about me, when you're a light bulb tycoon.-- gizmo, Dec 14 2001 I've seen warm spectrum flourescents and, when running on a 400Hz ballast, they are dimmable too (and they don't have perceivable flicker). Of course, they are expensive.-- bristolz, Dec 14 2001 At work, lg. I'll try and post you a link.-- neelandan, Dec 15 2001 Added idea 'Backup Filament Light Bulb' as seperate idea. See link.-- st3f, Dec 15 2001 hey giz, don't forget your mate when your rich and famous.-- alexo, Dec 15 2001 I know that some headlight bulbs are dual filament, so are some taillights. The difference as you say is circuitry. What I'm talking about is the normal filament at the top of the support wires in the bulb, and another halfway down, in the same bulb, using the same power supply.
I hate fluorescents, too. They always flicker, and get worse before they blow. <Am I the only person who can see ripples in the light of a bulb going bad?>
Another idea again...since LEDs have become fairly cheap, put several bright blue or green LEDs in such that when the bulb stops conducting electricity when the light is on, the LEDs come on. They won't give a huge amount of light <although it's more than you might think> but you won't be in total darkness, either. Electroluminescent panels might work too.-- StarChaser, Dec 15 2001 [StarChaser] No, you're not. Additionally, I can tell when many traffic lights are going to change because I can see them blink a bit before they do so.
There are light switches that have lamps built in that light when the switch is off (so you can find the switch). And night-lights that come on automatically are very baked.-- phoenix, Dec 15 2001 Perhaps I'm missing something, but my understanding is that incandescent bulbs pretty much only blow out when they're flipped on, as opposed to when they already have current flowing through them. I'm not sure anyone or anything can predict when that will happen.-- snarfyguy, Dec 16 2001 White LEDs are available, though expensive (around 150 times red when I bought one). Run strings of them around your bathroom ceiling and you might not need to change anything as they are reputedly everlasting. (Dunno. Mine went.)-- neelandan, Dec 17 2001 [neelandan] (off-topic-ish about LEDs)I don't know about the high-brightness LEDs, but normal LEDs don't last very long if too high a voltage is applied (in my experience, you can kill them in a few minutes from a 9v battery, or a few seconds from a 12v power supply). They especially don't like being operated in reverse for too long. On the other hand, if properly cared for, they can survive for many years.
I'm not sure that high-brightness white LEDs are a cost-effective way of achieving this aim, though.-- cp, Dec 17 2001 Snarfyguy, they break most often when turned on because the inrush of current overheats a thin area in the worn filament, and it breaks. They do break while in use, I've seen it happen, but very rarely.
White LEDs are really overpriced at the moment, but they'll come down; there are little rubber covers with phosphors that you can put over a cheap blue LED to make it show as white available now. <Unfortunately, I can't find the link that had them anymore. Grumble>-- StarChaser, Dec 17 2001 Snarfguy, I think you might be mistaken about lights blowing only when current is applied, not when current is already flowing through. More than once I've come back from a week away to find that the light I left on (to fool extremely unobservant burglars) has blown.-- lmc9, Dec 17 2001 I wonder if there are any cars that have had the "check engine" light bulb burn out because the engine is such a piece of junk? I can see it now...750 hours of "check engine".-- Amishman35, Dec 28 2001 The higher the temperature of a lightbulb filament, the less reddish the light, the more electrically efficient, and the faster it will burn out.
Having two filaments, one which runs much cooler than the other, would provide an effective means of providing a 'back-up' bulb, but most of the power used by the second filament when the first one was also working would be wasted.-- supercat, Dec 29 2001 random, halfbakery