Introduction: Make a Small, But Powerful 30KV Van De Graaff Generator

Picture of Make a Small, But Powerful 30KV Van De Graaff Generator

What is a Van de Graaff generator? you might wonder, well It is an electrostatic machine that builds up an extremely high voltage charge on a metal sphere. It was invented by Robert J. Van de Graaff in 1929.

it works like this: you know how when you scuff your socks on a carpet, and then get that nasty shock by a door knob? Or how rubbing a balloon in your hair will cause the balloon to cling to the wall? Well a Van-De-Graaff generator is a automated version of this effect, known as the “triboelectric” effect. As the belt on the generator come in contact with the bottom roller, depending on the material used, the belt and roller will gather opposite charges. The charge on the belt is then carried up to the top roller, where it is deposited onto the sphere.

in this Instructable, I will show you how to build your own Van De Graaff generator, so you could be a mad scientist too!

Step 1: Step 1: the Parts and Tools

Picture of Step 1: the Parts and Tools

Now lets get building! You will need:

*lots of duct tape and electrical tape,
*a top load,
*a plastic tube about the size of a marker, (and yes, you could use a gutted marker too),
*a wide rubber band,
*a fuse,
*a small motor (preferably with a long shaft),
*a power supply to power the motor
*some paper clips
*some wire
*something soft and insulative to mount everything to. I used a white-board eraser

as for the tools, you will need:
*a soldering iron,
*wire cutters (recommended)
*hot glue gun or rubber cement,
*scissors and a sharp knife
*common sense.

Step 2: Some Dangers:

Picture of Some Dangers:

Even though this is only static electricity, it doesn't play nice with sensitive electronics like computers, phones, hard drives, thumb drives, etc. I highly recommend if you don't want to fry your new $750 computer or your expensive android, that you operate this far enough away from any electronics. for this small one, a few feet should be enough. I will not in any case be held liable for your actions.

Step 3: Building the Generator

Picture of Building the Generator

First, we need to gut the marker. Take a pair of pliers and pull off the ends. After that, make a quarter inch hole close to the bottom of the marker tube. (I did this by melting a hole into the plastic with the iron.) Make sure it is big enough to fit the motors shaft though it. (you might need to drill a hole at the opposite end if the shaft is long enough to go all the way out to the other side).

Next, we need to take our motor, and cut a piece of electrical tape a little wider than the rubber band, and wrap it around the shaft to make the bottom vinyl roller. Solder some wire to the motor contacts, and add some hot glue on the exposed contacts to insulate them and prevent corona.

next, shove the rubber band down into the tube. make sure it is aligned with the two holes. now take your motor and fit it tightly into the bigger hole. make sure the shaft goes though the middle of the rubber band and that the motor shaft is vertical with the tube. (one way to ensure this is to press the motor up against the plastic leaving no space.) now hot glue it into place.

Take the fuse, and touch your hot soldering iron to the end cap. the heat should make the cap fall off after a minute or so (tip: put a  blob of solder in the iron to make this easier) after you have done this to both caps

unbend the paper clip, and then bend a 90-100 degree turn in it almost in the middle. grease up the paper clip near the bend, then take the glass roller and slip it down the clip. carefully, take a pair of pliers and make another bend the same as before, it should be so that you could tape the two ends to the tube. the top roller should look like a \''''/ shape, the ''"" being the glass piece. lastly, bend the very end upwards so corona will shoot towards the top piece, instead of shooting to ground. this will help prevent unwanted arcing and leakage

Almost done!

Slip the other end of the rubber band over the glass roller and secure the two ends of the paper clip brace to the end of the tube furthest away from the motor. I used duct tape, but hot glue should work too. The top roller should be as close to as parallel to the bottom shaft as possible. Test to see how well the rubber band moves around. If it immediately moves one to one side and gets stuck, adjust the paper clip until it stays centered.

Now add the brushes. stripe some wire about a 1/2 an inch (1 cm) off, and separate the bristles out as shown in the picture. Do this to two wires, each about 3 inches long or so. Strip off the other side about a 1/4 inch (6 mm) and put a solder blob on them to prevent sharp edges. Mount the first wire to the top, and have the bristles very close to the rubber belt, but not touching (even though having it touch will increase the output, it wears out on the belt quick. you can see distinct lines in my belt where the wires touched the belt.)

Step 4:

Picture of

Well that's about all. thank you for visiting, and don't forget to rate, comment and subscribe!


mihir.sahu.355 (author)2015-06-21

i don not get a wide rubber band what else can i use

-max- (author)mihir.sahu.3552015-06-22

Rubber mobius strip?

But really, any wide belt or band made out of an insulative material halfway between vinyl and glass on the triboelectric scale. Yeah a rubber band is probably your best bet unless you understand the science well enough to figure out a better and more practical solution.

mrmolamola (author)2014-12-31

Can I use a cardboard tube instead of a plastic tube and does the rubber band have to be tight an does it matter how wide the rubber band is?

-max- (author)mrmolamola2014-12-31

Do not use cardboard as it is not sturdy enough, and it will absorb moisture in the air significantly impacting performance. The rubber band does not have to be very tight, but it cannot have a lot of slack either. The more rubber that comes into contact with the glass tube at the top and the rubber at the bottom, the better the generator will work, so yes, the wider the rubber band is, the better.

mrmolamola (author)-max-2015-01-10

Thank you! but when I got all the materials(I was asking about the cardboard and the rubber bands because I had to do a bunch of improvising) I accidently cracked the fuse. Will it still work? And my motor's spoke was to short so I hot glued a piece of cardboard to the center of my tube so the rubber band won't fall off and it isn't working. The rubber band is touching the cardboard in the middle. Could this be the reason why it isn't working?

sarvesh7 (author)2014-05-16

very nice project. is the upper bristle wire's other end connected to the dome?

sarvesh7 (author)sarvesh72014-05-16

and does the sparking outside stop the motor for a while?

sarvesh7 (author)2014-05-16

nice soldering skills

-max- (author)sarvesh72014-05-16

What soldering? You mean the soldering for the wires? Thanks.

superbotboy (author)2013-12-15

can i use wool instead of wool?

superbotboy (author)2013-09-17

its a great science project. i made it and won in my school science fair too.the problem now is that i cant find a fuse. What can i use instead of a fuse or anything made up of glass. Can i use a pen refill?

-max- (author)superbotboy2013-09-17

I only used a glass fuse because it is made out of glass, and a quick look at a triboelectric chart shows glass as mostly positive (it tends to give up (e-). Anything along the lines of a glass bead or tube can be used, or even another material with a similar triboelectric charge. You can even use a small metal tube of similar dimensions, but I have never tried it, and so I can't guarantee it will work.

What do you mean by pen refill? If it made of plastic, it will probably give bad performance or not work at all. However, if it is made of a material that is in the high in the "positive" region of the chart, it should work.

scristian (author)2013-03-04

well i built it but it doesn't work... can u see it there are any
problems with my bult pls (i used a screw instead of the bottom brush)

-max- (author)scristian2013-03-07

the first thing I noticed was the top brush "points" are supposed to face the band. the charge can easily jump to them and get carried to the dome (coke can). also the top brush is simply too close to the motor. the charge will jump and leak directly to ground. for noticeable voltages, in your config, you need to have the top roller as high as possible. also, the brush needs to be inside the can, otherwise the charge on the outside of the can will repel the charge on the brush. this, as one can imagine, will severely limit the performance of Van De Graaff generators.

after you extend the generator longer and fix the brush design, your output should be very good. to test to see if it is not the can leaking the charge,Take it off and smell the output wire/brush for the unmistakable smell of corona. If you feel a wind or draft coming from it than you know everything is working exempt the top piece

on some days, my generator refuses to work at all for no apparent reason, and other days, it works (almost) flawlessly. it might have to do with humidity, but I don't know for sure.

scristian (author)-max-2013-03-08

thank you, i'm sure i'm not the only one that will be helped by this

-max- (author)scristian2013-03-08

Your welcome. by the way, did you get the generator to throw long sparks? or still working on it?

scristian (author)-max-2013-03-08

yeah.... i kindaw broke the drive shaft so i got to repair it and make it better that before

scristian (author)scristian2013-03-08

and i made it as a test to see if i could actualy built one. Now i got 1 year to built a big one for a school project

scristian (author)2013-03-05

oh it works... it was justrly small. tnx for the instructions

scristian (author)2013-03-04

i also made big rolls or electrical tape around the ruber band on the bottop roller to keep it centered

scristian (author)2013-03-04

can i use a soda can as the top dome?
and where does the ground whire go?

-max- (author)scristian2013-03-04

Absolutely! The only problem is that in needs mounted firmly, otherwise it wobbles around and physically doesn't work well in my particular design. Some modification should allow it to work better.

The ground wire is connected to, well, ground. more specifically to a rod driven into the ground, a copper water pipe, or other metal objects in the house that are electrically connected. I use the negative of the power supply as the ground. The ground can also attach to a discharge "wand" often being myself holding a coke can.

Phil B (author)2013-01-24

Thank you for this. I tried to make a larger Van de Graaff static generator a few years ago, but it never generated a charge and I gave up. We were living in a fairly humid location at the time, so that may have been a factor. My plan had been to get it working and donate it to the science program at an elementary school. I am surprised your generator works so well when assembled quickly with hot glue and tape. Finding a suitable belt, especially for a larger unit is always a challenge. And, I tried to get a dome that is as spherical as possible with as few sharp edges and corners as possible. I had intended to use a metal salad mixing bowl.

-max- (author)Phil B2013-01-24

My first attempt to make a generator was with erector set pieces, and it did not work at all. back then I didn't understand how they worked and though it was by friction and rubbing against another dissimilar material. I look upon that attempt and i see so many thing just completely wrong with it.

On my second attempt (this one) I learned a lot (including the fact that actually do need a top piece), and I myself, am surprised at how well this design works as well as how quiet it is! (20-30 decibels?) only a little louder than the motor itself when it is adjusted properly, otherwise the glass fuse likes to rattle a lot.

to fix sharp edges, tape works well. it covers up and prevents the charge from 'leaking' into the air.

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