The Van De Graff generator is a device capable of generating potentially millions of volts of electricity which you can build in an afternoon, probably from parts you’ve got in the junk bin. This is not a fact that’s escaped the notice of hackers for decades, and accordingly we’ve seen several Van De Graaff builds over the years. So has high voltage hacker [Jay Bowles], but he still thought he could bring something new to the table.
The focus of his latest build was to not only produce one of the most polished and professional versions of this venerable piece of high voltage equipment, but also make it accessible for others by keeping the design simple and affordable. The final result is a 40,000 volt Van De Graaff generator that’s powered by two AA batteries and can fit in the palm of your hand.
Put simply, a Van De Graaff generator creates static electricity from the friction of two metal combs rubbing against a moving belt, which is known as the triboelectric effect. The belt is stretched between the two combs and passes through an insulated tube, which serves to “pump” electrons from one side to the other. The end result is that a massive charge builds up on the positive side of the Van De Graaff generator, which is all too willing to send a spark firing off towards whatever negatively charged object gets close enough.
The video after the break guides viewers through the process of turning this principle into a practical device, illustrating how remarkably simple it really is. A common hobby motor is used to get the belt going, in this case just a wide rubber band, and the rest of the components are easily sourced or fabricated. Even for what’s arguably the most intricate element of the build, the combs themselves, [Jay] uses nothing more exotic than aluminum foil tape and a piece of stranded wire splayed out.
Combined with the acrylic base and the purpose-made metal sphere (rather than using a soda can or other upcycled object), the final result not only generates healthy sparks but looks good doing it. Though if the final fit and finish isn’t important, you could always build one out of stuff you found in the trash.
21 thoughts on “Mini Van De Graaff Is A Shocking Desk Toy”
The build up of static ,luckerly is shorted out, The above condition has been naturally generated inside machines since the introdution of plastic on metal parts, This caused machines to overide their circuits and kill people, (UNTRACEABLE)! By the principle of simply running a plastic comb through your hair and picking up bits of paper with the charge build up.The same applies to machinery, with heat or electrical wiring outside insulation IONIZATION of the air takes place, Strangely these like to adher to plastic parts,and ignore normal machine grounding.By running a seperate grounding wire only fitted to plastic parts then connecting to power in earth is all eliminated
Circa demonstrated GAF Corp 1970.
Yes, actually one of the more annoying things about messing around with Van Der Graffs, is the static buildup/feedback along all insulation on the low voltage supply lines, and even to power adapters and back along extension cords.
Van -de- graaf
You’re pumping up ions in the air, they get attracted towards places with the opposite potential – it happens because there’s voltage gradients in the air anyhow.
So what’s happening is, creating these ions in the air is making the air inside the room act like the electrolyte inside a capacitor. The charged up particles make the air conductive and allow current to flow through the building, collecting up against the insulators of ground wrings, while the opposite charges collect against the opposite polarity wherever that is coming from, like the ceiling or the floor.
Even under normal conditions, say you’re sitting at the window of a two-story house, there’s probably a few thousand volts of potential difference between you and the physical ground from natural sources. In a thunderstorm, much more.
Richard Feynman actually discusses this very early on in his lecture series, Volume 2 on electromagnetism in chapter 9. It’s entitled “Electricity in the Atmosphere” and largely deals with electricity and weather, obviously.
You can find it here on CalTech’s site, if you want to read it: https://www.feynmanlectures.caltech.edu/II_09.html
Read the title too fast. Was expecting a theft deterrent for a minivan.
I have thought about that on more than one occasion. The neighborhood I live in has an absurd number of car prowlers that go around at night looking for unlocked vehicles to steal stuff out of. I’ve always thought a Van de Graaff generator hooked up to the bodywork of the car would work well as a deterrent.
EVs might have an advantage.
Not trying to be morbid here, but you’d probably just end up witha ring of dead stray cats around your car.
Static electricity isn’t very dangerous & 15cm doesn’t build up much charge. Even thieves aren’t likely to be deterred.
So you have to place the electrode out of reach of cats, and/or place additional electrodes powered with a normal small electric fence generator in a way, that cats are deterred but not endangered. Cats are just lovely and need to be protected – I would not mind dead car thieves lying around that much :-)
Unless the body is very insulated from the chassis the tires are conductive enough to ground the car. Lightening strikes and low hanging power lines tend to blow tires.
“Science and Mechanics”, May 1961 “Midget Van de Graaff Generator Develops Up to 50,000 Volts”
(Alas, this doesn’t seem to be one of the magazines with an online archive. But: image.tech-domain.com/images/2009-10/midget-van-de-graaff-generator.pdf )
(Built one for an elementary school science fair! (don’t know what happened to it :-( )
I accidentally made a van-de-graaff once when I changed the multigroove-belt in a washing machine. The service manual stated a special type of belt which was three times more expensive than the normal off-the-shelf one and I thought “screw it and stick it to the man”. Bad decision. The controller blew up because of the vicious sparks and the washer was trashed (new controller was more expensive than a new machine).
After that I ran the machine with the cover removed and the lights off and the whole motor, belt and pulleys glowed blue-ish and the typical smell of ozone was released.
That was CORONA!
Actually the combs are the charge injector and pick-up devices; the actual charge ‘sucking’ from ground and charge ‘spitting’ towards the sphere is stimulated by the different materials used for bottom roller vs belt and belt vs top roller. Materials thereof are fundamentals.
Excellent explanation here, it made me make a powerful VDG: http://mark.rehorst.com/Van_de_Graaff/
P.S. I used nylon tape above regular plastic tubing for bottom roller, Teflon tape above regular plastic tube for top roller. Rubber belt was regular rubber band used for stretching. The combs I made out of IDC wire. Enjoy
I thought VDG generators worked properly because of the DISSIMILAR rollers? You might want to change one of them out for a metal roller, might work much better? Can’t remember which is which, but one nylon, one metal, experiment and find out which combination works best. If they’re both nylon, they’re theoretically fighting each other, and I suspect the only reason your generator works is ‘cos one’s accidentally better at triboelectrickiery than the other.
The VDG in this post’s video is using Teflon for the bottom roller and nylon for the top. Teflon is at the negative end of the triboelectric series and nylon is at the positive. Also crucial is that the inner surface of the belt must be a material somewhere in between and far from the roller materials in the series. His belt is rubber, so it all works.
Ah! For some reason I thought both were nylon. I sit corrected! :-D
Please be kind and respectful to help make the comments section excellent. (Comment Policy)