Carbon arc lamp

[brianl703]

I read about these when I was a kid, always wanted to try making one.

Well, I finally did it.

First I took two AA batteries (of the el-cheapo "General Purpose" type) and removed the carbon rods from them by prying up the + cap and peeling the metal away with pliers. This, by the way, was very easy. Batteries used to be a lot harder to disassemble...

Then I took two lengths 14 awg solid copper wire and wrapped each length around a carbon rod. (You could probably use alligator clips instead).

I took 3 12V 7 amp-hour UPS batteries and connected them in series for 36V.

I connected each of the 14 awg wires (with a carbon rod at the other end) and connected them to the 36V source.

Then I touched the carbon rods together, drew them apart and I got a nice bright arc! I was careful to avoid looking directly at it because it is VERY bright and has a UV component.

I'm not sure if 36V is required, 24V may work but 12V definitely is not enough to strike an arc.

 

[Colt45ws]

hahaha, thats pretty cool. Wonder what the power consumption is.

 

[river_rat]

Awesome!
I love to tinker/experiment too...may have to try that myself.
Maybe you could make it handheld with a reflector.

 

[mechtech2]

That's all the power it needed?
No kidding.
How about an AC household power test, while you are at it?

BTW, you probably won't want to carry these test parts on your next airline flight!

 

[brianl703]

That's it. 36V is all it took.

It probably would have worked better with some sort of current regulation--the carbon rods were getting excessively eroded just from the short time they were arcing, so I suspect the current through them was too high.

(I didn't think to hook up my clamp-on DC ammeter and take a reading!)

I think AC power will make the rods erode even quicker and probably trip a breaker. Current regulation would definitely be needed there. I suppose one could maybe use a welding power supply, those are typically current-regulated aren't they?

To make this work in production I think you'd need (1) current regulation and (2) some sort of mechanism to adjust the arc gap as the carbon rods erode.

 

[mechtech2]

With DC did only one side erode?

 

[brianl703]

They were both eroding. One might have eroded more than the other, I didn't measure them when I was done.