Although the basic concept of electrostatic attraction has been known since ancient times, it was only in the 17th century that scientists began to systematically investigate electrostatics. One of the first to explore this new field was Otto von Guericke, who constructed an electrostatic generator to help with his experiments. [Markus Bindhammer] has reconstructed this machine, which formed the basis for later work by the likes of Wimshurst and Van de Graaff. [Markus] kept his machine in an almost period-correct fashion.
Von Guericke’s machine consists of a sulfur ball mounted on a spindle that allows it to be rotated and rubbed against a piece of cloth. By doing so, the ball gains a charge that can be used to attract small pieces of material. [Markus] built a neat wooden frame with faux-antique carved legs and installed a handle, a spindle, and a belt-drive system to rotate whatever’s mounted on the spindle at high speed.
All of this is beautifully documented in [Markus]’s video, but by far the most interesting part of his project is the process of manufacturing the sulfur ball. If you’ve always wanted one, here’s how to make one: first, melt some pieces of pure sulfur in a round-bottom flask using an oil bath. Then, turn on your vacuum pump to remove any air or water vapor trapped inside the liquid. Once the liquid is nice and clear, let it cool down and solidify very slowly; the sulfur ball can then be released from its container by breaking the glass with a hammer.
The Van de Graaff generator is a staple of science museums, to the point that even if the average person might not know its name, there’s an excellent chance they’ll be familiar with the “metal ball that makes your hair stand up” description. That’s partly because they’re a fairly safe way to show off high voltages, but also because they’re surprisingly cheap and easy to build.
In his latest Plasma Channel video [Jay Bowles] builds a large Van de Graaff generator that wouldn’t look out of place in a museum or university, which he estimates is producing up to 500,000 volts. It can easily throw impressive looking (and sounding) sparks 10 inches or more, and as you can see in the video below, is more than capable of pulling off those classic science museum tricks.
It’s really quite amazing to see just how little it takes to generate these kinds of voltages with a Van de Graaff. In fact there’s nothing inside that you’d immediately equate with high voltage, the only electronic component in the generator’s base beyond the battery pack is a motor speed controller. While everything else might look suspiciously like magic, our own [Steven Dufresne] wrote up a properly scientific explanation of how it all works.
In this particular case, the motor spins a nylon pulley in the base of the generator, which is connected to a Teflon pulley in the top by way of a neoprene rubber belt. Combs made from fine metal mesh placed close to the belt at the top and bottom allow the Van de Graaff to build up a static charge in the sphere. Incidentally, it sounds like sourcing the large metal sphere was the most difficult part of this whole build, as it took [Jay] several hours to modify the garden gazing ball to fit atop the acrylic tube that serves as the machine’s core.
We use electricity to move things with the help of motors and magnets all the time. But if you have enough voltage, you can move things with voltage alone. As [James] found out, though, it works best if your objects — ping pong balls, in his case — are conductive.
He wanted to add a Van de Graaff generator to add to his “great ball machine” which already has some cool ways to move ping pong balls. However, to get the electrostatic motion, [James] had to resort to spraying the balls with RF shielding spray.
There probably comes a point in every female technical journalist’s career at which she covers her first make-up story and wonders aloud whether this is what her life has come to. But this make-up story involves some physics, and follows a series of viral videos in the TikTok community in which specialist cosmetics vloggers were surprised to see lip gloss apparently levitating — defying gravity — from the ends of its applicators. This caught the attention of [Steve Mould], who followed up on his hunch that static electricity might be responsible. What follows in the video below the break are a variety of attempts to recreate and characterise the phenomenon.
The tried-and-trusted approach of rubbing feet on the carpet failing to cause any movement in the damp atmosphere of a British January, he’s off to try a Van de Graaff generator Even the hefty electrostatic charge from that failed to produce more than a tiny blip, but did at least give a suggestion that the effect might be electrostatic.
Finally he was able to replicate the beauty vloggers’ results using the FunFlyStick electrostatic toy, with satisfying threads of lip gloss heading off into the air. The FunFlyStick is an interesting device in its own right, being a Van de Graaff generator in toy form and capable of generating significant quantities of charge. The flying lip gloss is an interesting phenomenon, but speaks further about just how much electrostatic charge can accumulate on mundane objects in a dry climate. Those of in damper climes would do well to take note before we travel.
The device is a simple but effective design. An antenna is used to capture RF signals, and these are then amplified through a single transistor stage. This is connected to a basic transistor flasher circuit, which is biased to only flash when tipped over the edge by an incoming signal. After building the circuit, [Jay] noticed that the device wasn’t just picking up signals from lightning, but also those from many other smaller discharges. The device was able to detect a shock from wearing socks on a wood floor, as well as discharges from a Van de Graff generator and even just from getting out of a chair!
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.
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.
We tend to think of electricity as part of the modern world. However, Thales of Mietus recorded information about static electricity around 585 BC. This Greek philosopher found that rubbing amber with fur would cause the amber to attract lightweight objects like feathers. Interestingly enough, a few hundred years later, the aeolipile — a crude steam engine sometimes called Hero’s engine — appeared. If the ancients had put the two ideas together, they could have invented the topic of this post: electrostatic generators. As far as we know, they didn’t.
It would be 1663 before Otto von Guericke experimented with a sulfur globe rubbed by hand. This led to Isaac Newton suggesting glass globes and a host of other improvements from other contributors ranging from a woolen pad to a collector electrode. By 1746, William Watson had a machine consisting of multiple glass globes, a sword, and a gun barrel. Continue reading “Hair-Raising Tales Of Electrostatic Generators”→