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In this brief video, MAKE contributing editor Bill Gurstelle demonstrates a simple arc light (a precursor to the incandescent bulb) using a length of carbon rod, a knife switch, some ceramic insulators, Nichrome wire, and an 18-volt power tool battery.

How to Make an Arc Light

Gareth Branwyn

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor for Boing Boing and WINK Books. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.


  • justDIY

    I remember making these with my father twenty some years ago, rip apart a dead carbon zinc battery, put the rod in the pencil sharpener to give it a nice tip. we used automotive jumper cables to hold the rod and some nails in a board to position them. no ballast resistor was used, just hook the cables straight to a car battery and BAM let there be light! I do recall it was incredibly bright and filled the basement with smoke.

  • Canine

    If you try making one of these then it should be pretty obvious, but worth stating – Don’t stare at the arc, it’s not going to be good for your retina.

    Not that you can really stare at it anyway, since arc lights get very intense and your blink reflex kicks in, but worth reiterating.

    Also, there’s likely to be a rehash of the old ‘Swan/Edison invented the incandescent lamp first’ argument, but I’ll leave that one well alone :)

  • Curious G.

    I see how the basic set up works, but how does the wire fit into this, and where does it attach? What’s it for? I don’t understand.

  • https://me.yahoo.com/a/1V_DvTl2kM7h.qn5TtG28I4yF5VCiiU-#9227b

    When I was in high school, I was the projectionist at an older theater that still used dual arc-light projectors. After switching over for each 20 minute reel of the film, we had to check, and replace if necessary, the carbon rods inside the projector. There were motorized feeders that fed the rods together and the rods were clamped in water-cooled copper holders. There were also knobs outside the projector to adjust the position of the rods. After changing the rods, you would turn on the power and “strike” the rods together to start the light (you watched the arc through a welder’s glass tinted window). A large front surface parabolic mirror focused the light through the film.

    The projectors were extremely hot, so in the summer the temperature in the projection booth could be very high even with air conditioning. If the air conditioning went out, it would be well over 100 degrees.

    If you opened the projector shell without letting it cool down a bit, the big expensive mirrors would crack (happened to another projectionist). If you let the carbon rods burn down too short, they would melt the copper holders and the water from the water cooling rig would spray out and cause all kinds of problems (including shattering the mirror). Never saw that happen, but I heard out it.

    BTW, many (if not all) big spotlights still use arc lamps.

  • Simon

    There is a good illustration of a mechanical sounding arc lamp striking in the opening credits of the old TV programme called Connections with James Burke. It is available on YouTube and well worth watching. I think curious Makers would find it interesting.

  • MadSciMatt

    Well thank you for making this video; nice to know this can be achieved in a home work space. However, the reason I came to make.com and took the time to watch (I’m old-school, preferring text instructions whenever possible), is that I would like to MAKE an arc lamp, myself. To that end, I have a suggestion for your videos: please include sometajhby him