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Using Nichrome Wire

The question comes up most often before the 4th of July (Independence Day) in the USA. People want to set up fireworks or other devices to be launched electrically from a distance (remotely). Most often, these devices are already equipped with fuses so the question is how to ignite the fuses electrically -- what size nichrome wire and what voltage should be used.

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One method is to use a needle, poke a hole through the end of the use and insert a short piece of nichrome wire. Use 1" of 30 gauge nichrome wire. It is best to use a lead acid car, motorcycle, or lawn tractor battery or you could use a 12 volt transformer plugged into a wall outlet. The transformer should be able to handle at least 5 amps. You might also be able to use a 6 volt lantern battery. 6 volts is plenty but you will probably have to put two square ones in parallel to get enough current from them.

The second method is to use about 3" of 30 gauge nichrome wire and make about 5 closely wound wraps around the fuse. Don't let any of the wraps touch each other, though. In this case, as long as you have at least 5 amp capability, 6 volts will still work but will turn the wire red hot but not hot enough to melt it initially. It will be enough to ignite the fuse, though. 12 volts from a lead acid battery, transformer or power supply is much better. Again, make sure you have at least a 5 amp capability. This means a 50 VA 12V transformer will do it because it is a very short duration application. It wouldn't handle it for continuous use. a 100 VA 12V transformer would be better.

If using a battery, you can use heavy lamp cord (12 gauge preferably), put a couple of large spring loaded clamps on one side and small alligator clips on the other end. Clip the alligator clips to the ends of the nichrome wire. Connect one of the large clamps to one terminal of the battery. Touch the other clamp to the other terminal to ignite the fuse. You could also put a push button in the circuit so you could attach both clamps to the battery (or transformer or power supply) and use the button to complete the circuit and ignite the fuse.