Hamfest! and Jacob's Ladder

So, I went to the hamfest again this year. (Big surprise, eh?) Lots of neat stuff, but most of it not stuff I'm willing to buy; I generally go more to look at the old stuff than to buy it. But this year, something caught my eye...

A 15KV 450VA neon sign transformer, set up as a Jacob's Ladder! I've always been a bit fascinated by high voltage, so I bought the thing. And it's been fun to play with!

Here are some time exposures of it in action. The exposures range from one second to about four seconds. What basically happens in a Jacob's ladder, is you have two wires, one on each output of the transformer, arranged in a V so that the wires are very close at the bottom and farther apart at the top. When power is applied, an arc forms at the bottom, where the wires are closest, then the hot air in the arc moves up, carrying the arc with it until the distance is too far and the arc breaks, starting the cycle anew.

It is mesmerizing to watch, and makes a really cool bzzzzzz sound as well. By adjusting the position of the wires you can get different effects, too.

In the time exposures, the arc leaves a trail that looks like a big flame. You'll notice horizontal striping; this is due to the AC waveform; the arc extinguishes and restrikes 120 times per second as the 60Hz AC waveform varies the voltage. Jacob's ladders that use DC are even more impressive, because the arc is continuous and much brighter.

I also had some fun subjecting a few random materials to 15kV to see how they'd react. Paper is no match for this much voltage, the arc goes right through and quickly ignites it. Neither is plastic from a CD case; instant ignition there as well. My favorite so far is an anti-static bag of the type used to package computer equipment. I put it across the two electrodes at the top and applied power; it immediately lit up with blue streaks and ignited in an impressive display of mindless electrical destruction. I'm glad I was doing this outside. Electricity is fun!

I'm thinking of someday building a Tesla coil with the thing. The hardest part to find will likely be a high voltage capacitor, but it'd be worth it!

Anyway, that was my adventure for this year's hamfest; I might go back on Sunday to see if there's anything else cool.