Home made igniters

I want to know if the filament material used in 500w halogen lamps would make a good igniter for RMS engines. I have seen others mention nichrome wire. The wire used in the filament is made of tungsten alloy (I believe...).

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Not really. The problem is not in its ability to take heat, but in the amount of current you would have to pump through it. A 12V battery does not have the juice to get it NEARLY as hot as it is designed to take. It really is irrelevant how big of a 12v battery you have, as the resistence of the filament is constant, and so the 12v will always pump about 1/10 the current through it that the 110V would that it is usually used with. You will essentially get FAR too little current to heat it up enough.

Get some nichrome. It's cheap.

Originally posted by cjl
Not really. The problem is not in its ability to take heat, but in the amount of current you would have to pump through it. A 12V battery does not have the juice to get it NEARLY as hot as it is designed to take. It really is irrelevant how big of a 12v battery you have, as the resistence of the filament is constant, and so the 12v will always pump about 1/10 the current through it that the 110V would that it is usually used with. You will essentially get FAR too little current to heat it up enough.

Click to expand...

That's true only if he used the full length of the filament. If the bridge between the igniter leads is a tenth of the length of the filament, then the resistance of that portion is also a tenth of the resistance of the entire length. 12V will push the same number of amps through the small bridge as 120V will through a full-length filament (ignoring for the purpose of this discussion the difference between DC and AC current.)

If it was up to me, I'd use nichrome wire; it's cheaper than halogen bulbs.


Bill

Guys I tried to manipulate the filament in a halogen bulb and it proved to be too brittle. I guess the tungsten alloy is just too hard. Oh well.