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:
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.
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.
Next up a parts list......
Step 1: Parts List (give or take a few items...)
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
Super Glue medium thickness for the belt
Vinyl covered fabric for belt (shower curtain or cheap strap)
Step 2: Belt Material and were to get it!
What you need is 18 oz. Vinyl Coated Polyester
A very tough mesh fabric that is coated with vinyl making it waterproof with a high resistance to dirt, mildew, oil, salt, chemicals and UV. Outstanding strength. Made of top quality materials, will not tear, stretch, crack, rot or mildew. May be sewn or glued with HH-66 vinyl cement.
Were you can get it!!!
They have a 42 oz. version but I have not tried it.
I got mine in white, almost all the black materials I tested didn't do so well.
Step 3: Tools needed (give or take again...)
Table saw or equivalent (skill saw)
Torch(optional but makes it work better)
screw driver for what ever screws you use...
Hole saw or jigsaw
soldering iron w/solder
Step 4: Building the base Step 1
The top piece is 12" square with the hole centered in it. I recommend laying the two pieces on top of each other and drilling the four support bolt holes at the same time so they line up perfectly.
Step 5: Base step 2
After it dries, fit it threw the hole in the top piece of plywood and glue the bottom ring on to hold it in place.
Get it as tight as you can and it wont slip on you.
Step 6: Base, step 3
The reason I made it this was was so that you can adjust the belt tension and level the top roller to the bottom roller. You dont have to bolt the top on permanently just yet, you need to add the motor and and comb.
Step 7: Base step 4
A note on the combs both of them the top and bottom ones are nothing more than stick pins soldered in sheet copper. about 1/4" apart. the sharper the better. the bottom one is wired directly to ground.
the top one is touching a spring that contacts the sphere.
Step 8: Base step 5
Step 10: Base step 5 pic
The belt and matching pulleys came from the sewing machine.
The aluminum box I mounted the bottom pulley to is just a spacer, you don't have to build yours that way.
I made my motor clamp out of a couple of bolts and a scrap piece of metal with two holes drilled in it.
Step 11: Base (comb and bottom roller)
Note that the roller will be turning counter clock wise and that the pins are just above were the belt will leave the roller.
Step 12: Base step 6
I had a left over modem case that I put my power switch in, you can use whatever you like as long as you shield it.
Note: after operation, if you dont discharge the sphere you can get a shock from the power switch.
Step 13: Time for the top 1
I put to 4/40 bolts in the top of the machine for this assembly to sit on, this is a very loose design, just get it close without touching the belt and it will grab a great charge.
Step 14: Assemble The Belt
I recommend cutting the belt as pictured below, then gluing a patch over it. I put mine on some wax paper so I could use allot of glue and not stick it to my table. The patch I made was "V" shaped and about 3/4" wider than the seam. See pic in step 15 as well.
Step 15: Top roller
Step 16: Top roller another view and belt construction.
After you have cut and glued the belt, you can put it on, you simply use the four support bolts to tighten it up, don't go to far you just want it tight enough to spin, and not slap the side of the column when its up to speed, this will kill your charge. If your belt does not track right you can fix that by moving one side of the supports up a little at a time, go slow and make the belt center in the rollers. You can also "crown" one of your rollers, that is to make it "keg" shaped. The downside to this is that you lose a little surface contact and in turn a little recharge power.
Optional: you can make the top roller adjustable as well to help center the belt.
Step 17: Sphere
Take your time and cut slowly, the woven carbide disks worked best.
The first time I fired mine up it worked but had allot of sparks jumping from the bottom of the sphere, to solve or help this problem I fitted a copper ring for the sphere to sit on. This will fold the charge back up to it. If you dont have a pipe bender tape one end of the pipe shut, fill it with water and freeze it that way you wont kink it wile hand bending it.
After I got the copper ring bent in a circle I cut it and clamped it, so it could be soldered with the torch
I also cut several more 1/2 inch tall rings off the coupler and put them on the column, this keeps the voltage from creeping down.
Also make the sphere sit as high on the column as you can without losing contact with the comb inside, my sphere is around 4" down the column.
Step 18: Diagram
2= collector comb
3= top teflon roller
4=upward side of belt positive charge
5-downward side of belt, negative charge
6=bottom nylon roller
Step 19: Time to play
You will also get a great effect on a humid summer night out side in total darkness, you can view the plasma coming from you and the sphere.
Also once its running good, tape a thumb tack with the point out to the top of the sphere, watch the plasma jet from it.
take five pie pans and stack them on top of the sphere and turn it on, one by one they will float up and fly off the machine.
Hold a florecent tube in your hand near it, it will glow! (you will get a few sparks to you doing this be ready and dont drop the bulb)
I would build a discharge wand to, or stick with a metal ball on the end that's grounded to the machine. You can use a large tin foil ball and a good insulated wire.
You can take it a step further with a leyden jar like the one here:
Leyden jar of DOOM!
Just be careful with any leyden jar they let you store enough current to cause you serious harm.
Also it will hold a charge for sometime after you turn it off. So discharge it before your curious cat looks at his reflection and gets popped in the nose like mine.....
Step 20: In action
See it and other photos that I have taken here:
Nickademusss Photo Stream
Most of the best visuals with a Van De Graaff are in a dark room, the light is subtle.
Enjoy email with questions :)