Product: Lightbulb
Backup Filament Light Bulb   (+5, -3)  [vote for, against]
Don't get left in the dark when the bulb blows

A quick admission this is not my idea.*

Manufacture a light bulb with two filaments** in parallel (primary and backup). The backup filament is fitted in series with a resistor making that filament glow dimmer and last longer.

When the primary filament blows the backup stays on so that you can still see to find your way around.


*This idea was originally posted as two independent annotations in 'The Backup Bulb' (annotation by PotatoStew) and 'Blink bulb' (annotation by StarChaser). I think that this is a bakable, saleable idea so I thought I'd give it its own space.

**Before anybody points out (actually UnaBubba already did in 'Blink bulb') that the idea of putting two filaments in the same light bulb is baked in car headlights note that these filaments are operated separately and perform different functions. One is not a backup for the other.
-- st3f, Dec 15 2001

The Backup Bulb http://www.halfbake...The_20Backup_20Bulb
"At first read I thought this was to be a second filament in a single bulb, rather than an entirely separate bulb." - PotatoStew [st3f, Dec 15 2001, last modified Oct 05 2004]

Blink bulb http://www.halfbake...m/idea/Blink_20bulb
"Should think it shouldn't be too difficult to include a high-resistance emergency filament in the things..." - StarChaser [st3f, Dec 15 2001, last modified Oct 05 2004]

Three-way bulbs.
Originally posted by PeterSealy but I deleted all his annotations as he was trolling with an argumentative call of 'baked'. The man would call a telepathic cutting tool baked just because he had sharp fingernails. Harumph. [st3f, Dec 15 2001, last modified Oct 05 2004]

UB: I'm not going to develop this - I just want to see it happen. If any halfbakers do want to do something about it, drop me an email. If you convince me that you're serious I'll delete the idea.

If not this can stay up so that some passing entrepreneur with less imagination than a halfbaker can take it and run. They won't get a patent, though.
-- st3f, Dec 15 2001

The reason I didn't bother is that while it's a good idea, it's unlikely to sell. The bulbs will be more expensive, no less prone to failure and won't last any longer, there just won't be total darkness until it's replaced.

If someone wants to make a big deal out of it, go ahead; and if you do get some money, a bit of it wouldn't go amiss. Or a couple cases of really good beer.

Ok, what the hell. I'll email GE and Sylvania in a moment.

<grumbles at companies that make it impossible to get hold of them through email. What the heck is the point of a website, otherwise?>
-- StarChaser, Dec 15 2001

How many halfbakers does it take to change a lightbulb?
-- thumbwax, Dec 15 2001

I figured the second filament would be dimmer because it'd be heavier than the original, to keep the resistance up. I dunno...
-- StarChaser, Dec 17 2001

ok, I have thught about this idea of having a second filament inside a bulb. what happens when a bulb burns out is that a filiment gets disconnected or broken. the problem that I could see in this idea would be that the first filament will bounce onto the secondary filamint causing sparks and lowering resistance of the circuit. the only way I can see this idea working is if the filaments are made shorter and kept a distance apart where the will not meet if one is broken. this may also create a need to make the filaments shorter which will also make the bulbs dimmer.
-- vrjake, Jun 01 2002

When they break, the filaments generally spring upwards. Would be easy enough to put the backup below, rather than above.

And if it did end up shorting, it wouldn't really matter; a filament is a filament. It will run current through itself, thus glowing and working. You won't end up with two non-glowing filaments <or one and a half> because they're still high resistance.

Never did hear back from GE or Sylvania.
-- StarChaser, Jun 01 2002

I really, really admire your patience, Star. :)
-- po, Jun 01 2002

Slightly baked in several Xmas tree light string designs - if the filament breaks in a bulb in a series string, the circuit is still completed by an element (probably of similar resistance, but heat generating only.) Not sure what happens if they all burn up = maybe you end up with an Xmas tree heater ;)

-- csea, Jun 17 2004

random, halfbakery