900,000 volt Van de Graaff Generator Using Cheap Parts

Lets build a 900,000+ volt Van de Graaff generator!!

I built this one in about a week, using scrap parts from a sewing machine and materials ordered from http://www.grainger.com/Grainger/wwg/start.shtml

I have seen the larger machines in operation at my local science museum and this one does just as well. I have made hair stand on end and even pie pans float up and off the machine.

For an explanation of operation go to Wikipedia:

http://en.wikipedia.org/wiki/Van_de_Graaff_generator

ALSO, note that this machine can generate enough static to stop a pacemaker and any other digital device, keep people with heart problems away. Also if you dont wont to blow up you sensitive electronic devices make sure you either use the machine on a separate circuit or unplug everything you want to keep. I have also stopped watches and killed cell phones with it. The current is low around 27micro amps but that's a thousand times whats needed to kill say your flat screen TV or pc/laptop.

Well if your know anything about Van de Graaffs you know that the bigger and smoother the sphere or collector the bigger the charge. Any bump or lip on the sphere and all the charge will run to it and bleed off.

You see the voltage is determined by how much you can store on the surface of the dome, sphere, collector. I used a 12" stainless steel garden gazing ball. I bought it from a garden supply center for $40.00. it throws faint sparks around 12" and strong bright ones at 8" to a grounded door knob. That's 883,920 volts by the calculator or 4350 volts per millimeter.

The recharge rate or time it takes to build up a charge high enough to jump from the sphere is determined by belt speed and width.

I used an art program to generate some diagrams and several pics of the completed unit, its a simple mechanism and you could upscale it for a larger machine easily topping 1,000,000 volts. all you need to do it increase the sphere size and belt width.

This one is an upscale version that I used to test equipment at work and I used the little one to determine the best belt material.
I tried plastic tape, rubber, fabrics, and the hands down best was a plastic coated fabric used in hotel shower curtains. Its easy to cut and glue and lasts for a long time. The charge it carries was easily 50% better than everything I tried.

Also to get the most of your machine you will need to get your hands on some Teflon and some nylon to make the rollers out of. I ordered mine from Granger (links in parts list) I used the Teflon for the top and nylon for the bottom or drive roller. You can also get the Teflon from stacking little half inch thick disks cut with a 2" diameter hole saw from cutting boards. You could also make the top and bottom roller out of the same material and coat the top roller with Teflon tape.

Also if you want to boost your storage and spark a bit build this:
Leyden jar of DOOM!

I will try to list as many tips threw this process as I can. Its been several years since I built the machine and its worked well so far.

Enjoy,
Zachary M.
Clinton, TN

Next up a parts list......

Step 1 Parts List (give or take a few items...)

Sphere-- Garden gazing ball, stainless (glass or plastic will not work)
4" PVC sewer pipe 24" long
4" PVC sewer pipe coupling
2" Diameter 2.75" long Teflon roller Grainger Item # 2NJA2 http://www.grainger.com/Grainger/items/2NJA2
2" Diameter 2.75" long Nylon roller Grainger Item # 1UTY5 http://www.grainger.com
12" x 12" plywood 3/4" thick
12" x 18" plywood 3/4" thick
1/2" all thread (threaded rod) you will need enough to make four pieces 9" long.
1/2" nuts for the all thread, you will need 16 of them also 16 washers
4/40 by 1" bolts I used about 10 of them
Power switch, 120v 5amp
Sheet of copper, I got mine at the hobby store 9 or copper roof flashing at a hardware store.
box of stick pins
3/4 inch copper pipe around 14" long (I would get at least two feet so you have leverage to bend it)
120volt power cord
120volt sewing machine motor with drive pulley and belt. (mine was from a Brother) Or Usehttp://www.grainger.com/Grainger/items/2M033 and Small pulley Granger PN 1X459
12" x 12" PVC sheet 1/4" thick (thick plexi glass will work just as well, and look cool to!)
Axel for top and bottom rollers (whatever you can find, I pulled mine from the sewing machine)
120v panel light, optional
PVC glue
Super Glue medium thickness for the belt
Vinyl covered fabric for belt (shower curtain or cheap strap)

Comments

[methoxypropyl]

Your instructions are nicely done. The adjustment of the brushes could be made if you use a spacer like paper of various thickness to make positioning easier and more parallel. I haven't started yet but I assume the belt will have a tendency to centrifugally move towards the brushes if they are above the tangent point off the rollers? You say to move them just above where the belt is starting to loose contact with the roller. Are you saying that is very important or can the brushes be at the tangent of belt and roll? If so, then the likelihood of scraping is reduced.

[nickademuss]

If you use the right kind of belt it doesn't flair out very much.

You will find out that running the belt really fast doesn't help much because of leakage at the sphere to the air.

[methoxypropyl]

I have found that you can make rings or coils very nicely by first filling the tube/pipe with sand. You must make sure there are no cavities otherwise the walls will collapse in very small diameter rings or coils. This has been an extremely effective way to make cooling coils for the technology I work in. Also make sure the sand is contained to prevent it falling out. Moonshine anyone?

[toxicfrazzles]

I think it would be a good idea to swap the rollers over as the negative charge on the dome i have heard can attract radioactive residues but any way great design you came up with

[stpierre473]

We ended up just using a motor from an old singer sewing machine that does not have a ground. Could we use one of the metal threaded rods for a ground for the bottom Comb?

[nickademuss]

Yes, use the ground on a three prong plug and you should be fine

[tbogomolny]

So, I was hoping to build one of these for my science fair at school, and I was just wondering if there are certain safety problems. For example, if you were to touch this would it really hurt or kill you or wipe out your computer or something? This is very cool and I don't know too much about them so any help would be super appreciated.

[nickademuss]

Read the instructable, it describes issues I have had...

It wont kill you, (unless you have a pacemaker or other heart problems)
It does sting a bit when it shocks you....

I have stopped a watch with it, killed a cell phone, knocked a wired network out....so electronics and this VDG dont mix!

[dooleyfive]

NICKADEMUSS Your instructions say to use nylon on the bottom roller and teflon on the top. Another site tell us to use nylon on top and teflon on the bottom does it really matter? also the needles with the copper tails on the top and bottom rollers that connect to the motor and the sphere do they have to isolated from touching anything else ?

[nickademuss]

D O O L E Y F I V E !

caps means your screaming in typed messages.

The rollers need to be opposites on the triboelectric chart:

http://www.esdsystems.com/whitepapers/wp_tribocharging.html

swapping them changes the polarity of the VDG.

THe lower brush as stated in the instructions is grounded, and because its mounted to plastic is isolated. The upper brush is in contact with the sphere and the sphere being up on a plastic pipe is isolated.

[Higgs Boson]

would wrapping the bottom roller in nylon thread have the same affect as having the actual nylon roller? Do you need to readjust the brushes a lot on this vdg? would any insulator work for the belt (like rubber, vinyl,)?

[nickademuss]

THe bottom roller needs to be nylon and smooth, the brushes once set dont need much adjustment, I tested several belts and the vinyl coated fabric was the best.

[Higgs Boson]

Okay. Thanks. One last thing. the rings that appear on the generator which you said "keeps the voltage from creeping down" would those just be corona rings?

[nickademuss]

yup

[bluetrilobite]

i followed this guy's instructions :) http://mark.rehorst.com/Van_de_Graaff/index.html

like he said ( and i tried it) it is sufficient to have a thin layer of the right material over each roller. He suggested teflon tape for the top roller and alluminium tape for the bottom. I did this and mine worked nicely until the homemade rubberbelt snapped :P
for the belt i think rubber/latex works well. I used for the first try a piece of bicycle tyre tube. he said that for him the tire tube didn't work but for me it did fine.

[Higgs Boson]

I was actually planning on using a belt made from bicycle inner tube, but because it is black in color, I realized it is likely to contain carbon and become conductive at high voltages, which would not work in a vdg. I have yet to finish one yet, so I haven't tried it yet.

[bluetrilobite]

i made a small vdg with a sphere 4" in diam.(11 cm) and by using the bicycle inner tube as belt i managed to get over 1 inch sparks (3 cm).
to be honest though i had to spin it quite fast... ...and then it broke :P

but i think that if you can find/make a rubber belt that isn't black (eg. tyre tube) its probably better.

[paperjack]

I don't understand, does the copper tail have to touch the sides of the sphere or it has to stay in the middle of the sphere without touching anything?

[nickademuss]

IT touches the sphere as close to the top center as possible.
So it can transfer electrons to the sphere.

[paperjack]

Can the sphere be far away from the comb? As in, not covering it.

[nickademuss]

It can but wont develop much of a charge.

[bluetrilobite]

hi. on the same note, i was thinking instead of cutting a big hole in the sphere so that the belt, comb, and roller can fit inside, would it be possible to run an insulated wire from the top comb ( which would be next to the top roller, just underneath the sphere) through a small hole, having it connect to the inside of sphere?
ty

[nickademuss]

Static dissipates so easily, it would work, but would be 1/2 the voltage....or less.

the best VDG's are enclosed this way.

[bluetrilobite]

hi.
I was thinking instead of cutting a big hole in the sphere so that the belt, comb, and roller can fit inside, would it be possible to run an insulated wire from the top comb ( which would be next to the top roller, just underneath the sphere) through a small hole, having it connect to the inside of sphere?
if no one knows i myght just try it anyway. if it doesnt work i can always make the hole bigger ;)
ty

[homeopathicfox]

Hi, I am Richard Fox and I appreciate all you have presented. I decided to make a bigger version of this and I am only getting a 1 inch spark. I have done something really wrong. I used an 8 inch green water pipe and 6 inch rollers It waould be great to talk to you in person. could you email me your telephone No. or could you call me at 510 590-1033. I would appreciate it. I think in a few minutes you could tell me your answer.

Thanks Dr. Richard Fox

[nickademuss]

Richard, send pics of your set up to my email [e-mail]

[homeopathicfox]

Hi, I forgot to add my email address. It is [e-mail]

Thanks Dr. Fox

[art.z]

Hi, very nice instructable.
I've been wanting to make a VDG myself but I have some questions:

What gives greater voltage and current?
The size of the gazing ball?
The materials of the rollers and belt?
Or the speed of the belt?

Plus, how do I measure the current and the voltage after it's done?


Thank You

[ultraVDG]

1. The size of the gazing ball is proportional to the achievable voltage - bigger ball leads to higher voltage.

2. The material combination of the rollers and the belt determine how many charge per area is on your vdg´s belt for transportation. But remember there is a limit (~ 26µC/m²). You can get around this limit (higher air pressure, SF6 instead of air, ...) but it´s difficult for "hobby scientists".

3. The speed of the belt is proportional to the current - more speed more current.

4. Because of corona loss you need enough current to get the ideal reachable voltage.

Measurement:
short circuit current: get an analog instrument (http://www.elv-downloads.de/bilder/artikel/Produkte/9/949/94971/Internet//normalneu/94971_w01_messmodul.jpg) you need 0-50µA or 0-100µA.
A digital meter will usually be destroyed without proper precaution.

voltage: spark lenght gives a rough estimate - there are tables. A calibrated field mill will do the job (http://en.wikipedia.org/wiki/Field_mill). An electric charge meter (http://www.elektor.com/magazines/2003/november/electric-charge-meter.55404.lynkx) can also be abused to determine voltages.

hope i can help,
ultravdg

[nickademuss]

couldnt of said it better myself :)

[mmboyajian]

I couldn't find any copper roof flashing. Can I use Aluminum roof flashing?

[nickademuss]

try your hobby store for copper sheet, aluminum would work but is very hard to solder to...

[stpierre473]

We are thinking about using a bigger motor one used for farm equipment with an adjustable dial. with two industrial mixing bowls welded together and and ground down on the edges then buffed. do you think that should give us more spark?

[nickademuss]

the motor should be fine, the important part is that you get the largest sphere without edges of any kind, it may be easier to get a garden gazing ball.

[seansippo]

do i want the bottom comb touching, or like the top one where it is close as possible without touching the belt?

[nickademuss]

as close as possible to the belt without touching

[checker5]

out of curriosity were did you get the Nylon and Teflon rollers

[nickademuss]

cole parmer for the nylon and teflon

[nickademuss]

also granger has it.... you can also use nylon bed rollers...

[bungalowdan]

To Author: I joined instructables to build your VDG. THANKS FOR THE PLANS. I plan to upsize to a larger ball and wider belt. One question: I don't want to fry any of my computers or other electronics. Since the charge is electrostatic, is the main concern the proximity of the VDG to electronic devices? Did you ever fry anything besides your computer speakers?