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Today my 8-year-old son comes home from school telling me he learned about lightning rods, and he says, "What if we could capture the electricity from lightning and use it to power stuff?" I'm aware of the limitations of capturing actual lightning, but I thought an at-home experiment could be fun. I'd like to help him create something at home that could generate a small electrical spark, and then something else that could capture the energy from that spark. Problem is, I'm not an electrical engineer and don't know how to design either of these things. There's a store here in town that sells things like circuit boards and capacitors, and I could borrow a soldering iron from work. I think if I could just get a materials list of what I will need, I could figure it out from there.

Can anyone give me some direction for how to accomplish this?

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  • \$\begingroup\$ A piezo igniter comes to mind. As in a lighter that has an electric igniter instead of a flint wheel. You may be better off showing him a hand cranked motor producing electricity. \$\endgroup\$ – Passerby Mar 16 '16 at 1:27
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    \$\begingroup\$ Since neither you or your son are well versed in electronics, something like a Jacobs Ladder or a Telsa coil are right out. \$\endgroup\$ – Passerby Mar 16 '16 at 1:34
  • \$\begingroup\$ But hey, a Van De Graff generator would be right up your alley. It's a static shock/cling generator. makezine.com/projects/make-28/simple-van-de-graaff-generator \$\endgroup\$ – Passerby Mar 16 '16 at 1:35
  • \$\begingroup\$ A Van de Graaff generator is exactly what came to mind when I was first thinking of this! I just couldn't remember what it was called. Thanks! That gives me some good direction. \$\endgroup\$ – ewoods Mar 16 '16 at 1:47
  • \$\begingroup\$ So the next question is, can I take the spark created by a Van de Graaff generator and store it in a capacitor (either store bought or homemade)? And then use that to power something like a small LED? \$\endgroup\$ – ewoods Mar 16 '16 at 2:03
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I would suggest you try building and using a Wimshurst machine

  1. It generates sparks (2 or 3 cm spark length easily reached)
  2. It can light a fluorescent light bulb (just hold nearby while cranking)
  3. Usually includes capacitors to demonstrate storing energy
  4. Is not electrically complicated
  5. Demonstrates generation of static electricity without direct friction
  6. Is mechanically simpler than a Van de Graff generator.

There are kits and finished machines avaliable, but you can build a Wimshurst machine in your garage workshop from parts you can get from a hardware store. I found I needed a drill press for some of the parts - hand drilled holes aren't straight enough for longer holes.

The difficulties in building Wimshurst machine are mostly mechanical.

You need some kind of bearings for the disks to run on, and you need to cut circles out of a plexiglas sheet. I used some plastic wheels with bearings for my disks to run on because I could get them cheap. One of the links below explains how to cut the disks.

Electrically, you do have to watch for sharp corners on the conductors - the charge "leaks" off through sharp corners, so smooth and sand everything round and use rods for connections as much as possible instead of flat metal.

You would have the same difficulties when building a Van de Graff generator, and more mechanical problems besides - most Van de Graff generators have a large dome for the charge collector, which can be difficult to make. The belt for the charge transport is also a problem.

Electrically, the Van de Graff is even trickier - the voltage can be so much higher that leakage is a much larger problem.

You also have to deal with powering it. While you could build a hand cranked Van de Graff generator, most information is about motor powered ones - probably because they take more cranking to build up a usable charge.

An alternative would be a Kelvin water dropper. It uses falling water drops to generate a static charge. I've never built one, so I don't know how well it would do for lighting things up.

  1. Link to a guy who built a fairly simple Wimshurst machine with detailed instructions
  2. Link to a Wimshurst related question here on stackexchange

This is my Wimshurst machine:

enter image description here

As you can see, it is mechanically fairly crude, but it does work.

I'll see about making a picture of it flashing a fluorescent lightbulb and post it later.


For something much simpler: Scruff across the carpet wearing sneakers while carrying a fluorescent tube. Walk over to a door and touch one end of the tube to the doorknob and watch the tube flash.
Weee!

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  • \$\begingroup\$ Thank you so much! That looks like the perfect thing to demonstrate the concept for him. I really appreciate the help. \$\endgroup\$ – ewoods Mar 16 '16 at 15:45
  • \$\begingroup\$ If you make an old fashioned Leyden jar to go with it, then you can demonstrate storage of charge - charge the jar on the Wimshurst machine, move the jar across the room, then touch a fluorescent light bulb to the jar contact and it wll flash. \$\endgroup\$ – JRE Mar 16 '16 at 15:57

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