Irrelevant Cheetah

So. As is probably self-evident, lately I’ve been doing all sort of non-bloggy things and then, well, not blogging about them. And it’s not like I planned it that way, it’s just the way things have worked out.

I plan to remedy that, however. One of the things I’ve always wanted to build is a Van de Graaf generator. This, for those of you not in the know, is that funny-looking machine with a metal sphere on top that shocks you when you get too close, and which will cause your hair to stand on end if you hold on to it for any appreciable length of time.

Now that I have some (too much?) time on my hands, I finally decided to build the damn thing. I took stock of my extensive inventory of electronic odds and ends and came up with a layout similar to this:

There is surprisingly little information on how to build one of these on the internets. There’s a lot of kits, and info about how they work, and even some “Here’s the one that I built but I’m not going to tell you how,” but not a lot of instructions. So I was going a bit blind, and there was a lot of guesswork and fumbling and flat-out mistakes.

The first result, which I didn’t picture, was pretty disappointing. It barely built up any voltage, and I quickly realized that the motor was too slow. This meant that I needed a motor with more power. I also needed a more uniform, smoother sphere, because if it’s not perfectly smooth, charge can “bleed off” rather than collecting on the surface of the sphere. My original design of two metal salad bowls soldered together was bunk. I finally managed to find a smooth metal globe in a garden supply shop, and I cannibalized a small automotive vacuum cleaner for the motor.

And you may feast your eyes on the final result:

Don’t these things just look awesome when they’re done?

It came out pretty well. As far as I can tell, it builds up a potential of more than 100,000 volts, which translates to a pretty decent shock. You can see the spark jump from the sphere to your finger across about 1/2″ of space. I haven’t been able to make my hair stand on end yet, merely because it turns out that this is really loud when it runs, and I don’t have the patience to listen to it long enough to let a big charge build up.

Perhaps the most amusing thing about this is that I’m not sure what to do with it, now that I’ve built it. If I decide to improve it, my next step might be finding a quieter motor. I would really like to make my hair stand on end, and the Offspring would like the same thing.

On the other hand, I have some more projects in the works, all of which are bloggable. I’ll have to see.