Van De Graaff Electrostatic High Voltage Generator




Introduction: Van De Graaff Electrostatic High Voltage Generator

About: Im a bit of a geek of all trades. Of late most of my free energy has going into Making sure our hacker/makerspace is awesome! Come check us out!

Step 1: The Parts for the VDG

The only parts in this that you are not likely to find at your local hardware store are the wheels.   I used bed frame wheels. their choice sorta dictated the size of Van De Graaff (Henceforth called VDG for short.)  More about the wheels later.

These are the parts used.
1 Lightbulb socket (I pried out the bottom most contact, to give less surface area to bleed off static charges.
1 Large globe lightbulb
1 1.50"" to 2" pvc adapter (lightbulb socket fits in here nicely, and gives space to mount the brushes)
1 2" to 3" pvc adapter
1 3" to 3" PVC Coupler
1 5" threaded rod and assorted washers and nuts,  I think it was 5/32"
1 6" threaded bolt, and washers, small enough for the wheel to glide on)
2 slightly curved plastic bedframe rollers. (was going to use skateboard wheels sanded down on my drillpress, but my dad had these in his shop)
1 3"x3"x1.50" PVC Tee
1 length of pvc (Ihad to use ABS which is not as good due to its carbon content, but it was all I could find in precut lengths, and didnt want to buy 9 more feet of pipe.
1 1.50" to 0.25" pvc adapter
2 sets of skateboard wheel bearings,
Some copper wire both to make a ground wire, and a spark wand wire, but also to make the brushes.
1 outlet plug (this is only connected to the ground pin
1 can of cold galvanizing spraypaint
1 can of copper metallic spraypaint
1 drill socket adapter. (to turn the bottom wheel)
1 drill, (optional speed controller)
1 sheet of latex exercise banding
1 tube of bike tire patch glue.
Teflon pipe tape,
copper foil tape
Other misc Stuff, A board to screw it down to and some long screws. and A binding post for the charge wand, some wire, a old junk drawer nob pull for the wand, some plastic tubing for the shaft of the wand.

Step 2: The Globe

From that other VDG instructable I mentioned in the first page, i got the idea to use a lightbulb,  but i knew the foil covering they used was inefficient, (too many bumps and corners)

I went with a large 8" decorative bulb.    And then I set about trying  make the glass (an insulator) conductive on the surface.  This involved trying to find out what spray paint was static conductive.

Sadly most is not!  after trying various paints on glass jars, i finally settled on a very high zinc content "Cold Galvanizing" Spray, from Rustoleum  this makes for a nicely conductive but ugly. globe

In my experiments Rustolium decoratives Metallic Copper spray was also fairly conductive. so i sprayed a topcote with that to make it more touchable and pretty.  (tested with and without both worked pretty well.

*I tried also making a rig to electro plate copper onto the zinc, and while i had soem success, the chemicals involved in the paint kept corrupting my plating solution,  im going to try again with conductive plating paint. someday! And probably do a new instructable about making copper spheres out of lightbulbs.

Step 3: Upper Wheel

As indicated in the graphics on the parts page, 

Saw two notches in the 3" down to the center line on the PVC Coupler,  verify your threaded rod can fit down in it nice and level. 

Assemble one of the wheels  onto the 6"bolt , and put washers and nuts on both sides.  slide it down into the notches. and finger tighten the nuts on the outside of the fitting.  (you will need to slide this out of the notches when putting the belt on. 

Using a few drops of superglue, glue some pvc Teflon tape to the upper wheel and cover it in about 2 layers of Teflon, superglue down the remaining tail

also go ahead and assemble the other parts,  the lightbulb socket, and the 1.50" adapter and the 2-3" adapter,  install loops of bare stranded copper wire around the single screw left in the light socket,  once affixed, snip open the loops to make lots of copper brush bristles,   bend/shape them to just glide over the wheel/belt to pickup the static charge and transfer it to the socket/and eventually to the lightbulb/globe

Step 4: Lower Wheel Assembly.

For the lower shaft,  its only supported on one side, (to aid with installing the belt later)

You need to press the skate barrings into the 1/2" to 1" adapter this will serve as support for the bottom wheel., i used some wood and my vice to squeeze them in, one after the other.

You also need to figure out where you want the wheel to ride in the PVC Tee adapter  best is about center,  mark the threaded rod and place your wheel where it needs to go, (you need about 1" or more rod to stick out through the bearings to power it with.

Now tighten on lock washers and nuts on either side of the wheel sandwiching it and making it turn when the threaded rod is turned

wrap the lower wheel in copper foil tape and insert into tee and out through the fitting with the bearings.  snap it into place.

Now make and install your brushes,  We made some loops of stripped stranded wire, and wrapped them around a screw and put them into the bottom of the tee fitting and snipped the loops to make lots of little broom bristle like brush points just grazing the side of the bottom wheel

Step 5: Starting the Assembly.

Step 6: Continued Assembly

For stability and ease of use,  I screwed it down to a square chunk of plywood.  just drilled some holes in the lip of the OVC tee, and installed long screws into the wood.

At this time we also drilled a hole for a ground wire to go tho the brushes, and also to the charge wand.  Both were run to a binding post we mounted on the board.

At this point you are about all ready to go,  you are going to need atleast one other person for the next step.

Step 7: Assembly

Prepare by removing the top roller by just sliding the axle up the sawed out notches. and set it aside,

you will also need a long semi rigid wire to fish the belt up the tube with,  (a untwisted metal coat hanger would work well, I used some stiff copper wire. 

make a hook out of your coathanger,

Put the top coupler on the top of the pipe,  and insert the coathanger  hook down the pipe.

place the belt (still using gloves) around the lower wheel, now hook the belt with the coathanger hook, and while standing up the PVC pipe, keep tension,  upping the belt up through the top fitting,  look down to make sure there is no twist or roll in the band.  Have your friend hold the coathanger up while you thread the upper wheel/axle through the band and let it carefully down into the notches.  when done it should look like a big conveyor belt.  tighten the upper bolts and give the lower shaft a quick spin with your fingers.

The curved (domed) shape of the wheels should keep the belt centered. but you might have to pre-center it a little bit.   make sure it does not keep wandering too far to one side or the other. this may indicate your shafts are not parallel and you will have to shim or fix, that.

Step 8: Done!

Lots of folks played with it during our big February event at our Hackerspace Quelab.  

If you are ever in Albuquerque!  Look us up!

Thanks and Enjoy!

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    68 Discussions

    do you happen to remember what kind of voltage output you got from this design?

    1.How do you make a discharge wand nobody online has a guide on how to make one.
    2. I fired up my generator and it worked fine when it didn't go to ground, but when I finally got my ground(the plug in I wasn't getting anything, why is that?

    Killbox another question please: My output sphere is 2 salad bowls taped together it stands at about 11 1/2" tall and 9" width in the middle. Also it is an oval shape. Will this still work? And what can I do about the numbers on the bowl?

    3 replies

    sure, the best collector would be a sphere, but you dont need the best possible, should be fine. as for the lumbers, im assuming those are measures? probably dont need to do anything, but if you really want some time with sandpaper or a dremmel with a grinder attachment could probably remove it, but it will probably always show.

    thanks hopefully, I will restart construction this weekend. I hope it will work . This project will de termine if I pass or fail the class.

    thanks hopefully, I will restart construction this weekend. I hope it will work . This project will de termine if I pass or fail the class.

    kill box: 1.does it matter which one of the rollers is on top (like if the copper was on top and the teflon was on bottom)
    2. I saw that on my steel bowls there are measuring numbers theres only 3 and I think they are only 1/4" big. Will they effect my charge output. If so how can I fix that (the numbers are dented on the inside and kind of pop out on the oustide if that makes sense)

    1 reply

    1: yes! i think thats the one thing that would matter the most, you want the copper one at the bottom feeding it electrons, and the teflon one above breaking them free and transferring them to the collector.
    2: bigger would be better, but mine using the lightbulb was not very huge and it worked. may limit your maximum spark

    killbox I have a few concerns:
    1. I was thinking about putting nuts on the outside of my top roller to keep it stable. Will this effect the ability to discharge when I have my roller and wire on the inside of the sphere?
    2. I also need some tips on creating something my sphere can sit on as support big does the hole in the sphere have to be?
    4. I got some dust on my copper roller. What is a good way to get it clean?

    1 reply

    1: if you can use nylon nuts or small sections of tubing i think that would be best, that way charge wont want to leave the top wheel that way. although if it did i dont think its the end of the world, as the static builds on the axle it will eventually saturate
    2: not sure, but if you make your hole in the sphere big enough to just barely go over your pipe at the top (i think you said you were not using a coupler on the top) you could go down atleast to the axle bolt. if you make it tight no mounting would be needed, if its a little loose a few wraps of electrical tape on the pipe would fatten it up.
    3: i think i answered that above, alot of the professional vandegraffs just put the support tube up into the sphere.
    4:Dunno, maybe a can of compressed air duster? probably wont hurt anything.

    Oh ok killbox. Heres what I am thinking about doing:
    I bring the wire from a hole in the tee a bit a above the bottom roller. I then pull the wire downwards, then I bend the wire a bit upwards then make an "L" shape at the bottom of the roller where the tips of the of the brush are a bit below the bottom. Will this also work?

    1 reply

    yes, i think so! its just a electron source so pretty much anything that can supply the belt with electrons, should work.

    So killbox to get this straight... from the hole on the bottom tee you brought the wire straight down from the hole, then you extended the wire down a bit past the roller , then you bent your bottom brush tips was they were pointing up toward the bottom roller not running parallel (that’s flat) with the bottom roller.
    1. DO I HAVE IT RIGHT? 2. Did you do the same thing with the top roller?
    3. Also if my wire extends more than ½” will it still work?
    4. And how did get your wire to stay put? every time I move just a little bit, the brushes move!
    5. I have seen people put there roller and brushes inside of the sphere. I don’t. I thought I would have my roller on the PVC, and brush wire attched to the coupling above the roller, then I have the sphere on the coupling. will it still be work?
    6. On a final note would it help if I send you pictures? If so how do I go about doing that?

    1 reply

    Sadly i cant provide pictures, since i have already sold this build at one of our yardsales but i did draw a very crude drawing, (warning im pretty bad with drawing in gimp, and this was a very rush job!) added it to the pictures in the step about the copper wrapped wheel.

    #3, sure, you only want it to lightly sweep the belt, but really it can be whatever length will work for you,
    #4 maybe you need a little stiffer of wire? not sure without photos of your brushes what may be going on, but once i got mine in place and fanned out and trimmed flat they were really no trouble.
    #5 yes the roller and the brushes inside would work a little better, less loss less bleedoff and such, but i was surprised to see how well it could work. using the socket and lightbulb (which would be impossible)

    killbox I have a couple more questions about the brushes
    1. When I do my bottom brush I drilled a hole a bit above the roller, had it coming straight down on the inside of the pipe, holding it together with a plastic loop, when I get to where I want the brush I bend the wire up and snake it to the roller. Will this still work?
    2. I got it when you said the brushes go with the direction of the roller when it’s rolling, but I am a bit confused about the tips of the brushes. Do they go along the wheel (basically flat) where the tips are a bit after the wheel, or are they before the roller, or in the middle of the roller? Or do they point upward towards the roller?

    1 reply

    mine poked into the side kinda even with the roller, but there is like a 1/2" clearence there so then they were bent upward in about a 45 degree angle to just barely have the tips touching the belt probably 1/2" above the roller, on the side where the belt would be going in an upward dirrection.

    Oh I forgot to add one more thing, my pipe in 16in long (giggity, giggity, goo) and i am cutting(2) 2 1/2 in slits for the top roller. is this to tall?

    1 reply

    I dont know if there is much of a maximum/minimum distance. My gut instinct is it will scale fine. ive seen 1' tall ones and 4' tall ones. although the on in the instructable was my first and sofar only one ive made.

    Thank killbox.
    1. I have heard people wrap electrical tape around there rollers to make a barrel shape then they put a thin layer of their copper or Teflon around it. Does this actually work?
    2. And was thinking about putting the screw below the roller, wrapping it up and try and get the brushes to glide on would this also work?
    3. I put my dome together by bonding the lids with epoxy and wrapped 4 layers of electrical tape on the outside, the rims are still on the bowls. Will this work?
    4. And I put 1 layer of electrical tape on the bottom where I cut a hole to reduce the corona charge (I think it’s called this). Do I need more layers?

    1 reply

    1, I dont know, mine were already barrell shaped, i cant see why it would not work.
    2, i think as long as your pretty much on or near the roller you will be fine.
    3, the lips of the bowls may cause some discharge but no i suspect you will be fine.
    5, static is a bit of a different creature than most electricity we are useto. a single layer of electrical tape can stop sparks from flying in the 1-800v range, but as voltage goes up it does need to be thicker, i can only say try it out, and then maybe try it with more to see if you see any difference. it will probably be fine.