| Author | Message | ||
     Anonymous |
Now I am using a Van de Graff generator for part of my school project, and the desgin you have puts out about 12,500 volts, and I need between 25,000 - 30,000. Now since I don't have a large conductive metal sphere, is it possible to somehow hook up two Van de Graff (of your design) together to double the voltage that something would receive? | ||
| Simon Quellen Field (Sfield) |
You might try looking at a beverage store for large barrel shaped aluminum beer cans. A gallon or two might make a nice top conductor. If you are not old enough to purchase the contents, I am sure a clerk will be happy to empty one for you if you pay full price for the empty can. I suppose you could try making two generators of opposite polarity (switching the materials on one so that the pulley and the belt are from opposite ends of the table on the web site). But I am not convinced that will work as well as you are hoping. The VDG is one of the harder projects to get working, because humid air, dirt, and grease are all good conductors at those voltages, and kids are not known for keeping things clean and dry. | ||
| Anonymous |
thanks.. so like you said, if I were to use the beer can or small keg, I could test the voltage by measuring how far the spark jumps from the can? | ||
| Simon Quellen Field (Sfield) |
That's definitely the cheapest and easiest way to measure high voltage. | ||
| Anonymous |
now I have a beer keg of the "bubba" size.. but it isnt completey smooth around the sides and has a rubber or plastic (cant tell) plug at the top... would that make a difference? Also... would an empty paint cant work if I cut a whole in the lid? | ||
| Simon Quellen Field (Sfield) |
The plug should not make a difference. The reason I suggested aluminum is that they don't have seams and are thus smoother in shape. The rounder the better. One little sharp point and that is where the electrons will concentrate, causing corona losses. | ||
| Anonymous |
Wow... thanks for all the help,, I cant think of anybody (or any site) that could of helped me so quick and on such short notice,,,, It means alot | ||
| Anonymous |
Now I have the materials but before I build it I was wondering is it totally safe, like to the touch, I only ask this because my parents have become a little worried so I thought I'd double check with you, thanks. | ||
| De Graff dude Unregistered guest |
Yes it is completely safe. Completely, except if yu maybe PUT YOUR EYE TO THE SPHERE. Otherwise, it is perectly fine. I HAVE A QUETSTION THOUGH. I MADE A VDG YESTERDAY, AND IT WAS OFF A WEBSITE-THE SITE SHOWED IT CLEARLY WORKS. I mad eit, and not a single volt. I could put my brainstem to the cables/sphere. NOTHING is created once it is turtned on. It is also supposed to created 12,500 volts WHY?! I am using rubber, glass, and copper for the cables My popcan has its actualy top cut off, and then flipped upside down, and one cable attatched loosly to the inside of the can. IS IT POSSIBLE THE SHARP EDGE CHERE I CUT THE TOP OFF IS MAKING ALL THE STATIC TO BE LOST???????? | ||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 143 Registered: 12-2004 |
Many things that you would not think of as conductors are actually pretty good at conducting high voltages. Paper, for example. If you are using a paper cup instead of styrofoam, you may be getting losses that exceed the gains. Keep everything very clean. Dirty surfaces conduct. Try different rubber bands -- many rubber bands conduct electricity at high voltages. Make sure that the brushes never touch the rubber -- a thin film of copper rubs off onto the rubber and makes it conductive. Make sure there are no sharp points anywhere but inside the can. That means don't cut the can top off -- cut out the inside of the top so the smooth ring is still there. | ||
| De Graff Dude Unregistered guest |
I am now on my fourth generaotr, all other three haven broken one way or another. I now understand the triboelectric series is for belt and roller material. I INTERPRETED IT AS THE TWO ROLLERS Also, I thought the farther from the center you get you have more of a charge, but then discovered it is for belt and roller materials. >>>>>My new generator is a beast, and the botton roller is pure nylon, and the top is pure teflon(tape). I am using any type of belt I can(it looks like fertilizer bags at this point) Saying all this, will my generator be more powerful than one with just aluminum and plastic rollers I REALLY HOPE YOU UNDERSTAND WHAT I MEAN. I just hit a crisis, and I dont know what to do. Should i leave my new generator with its teflon (tape) and nylon rollers, or change them to simple 'plastic and metal' or 'fur and plastic' Oh god, I hope you know what I mean- I dont know how to explain it any farther. | ||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 181 Registered: 12-2004 |
The bottom roller can be made of anything. Since you have a teflon top roller, you might want to try a nylon belt, but a rubber belt should do fine. To generate more current, run the motor faster. To generate higher voltages, use a bigger dome on top, the more sperical the better, although a donut shaped top collector will also do nicely. | ||
| De Graff dude Unregistered guest |
ohh ohh ohh, i always make a generator with a top AND bottom brush. Does this mean the lower wire can be connected to another sphere? You sure the bottom roller can be made of ANYTHING? i mean, wont Nylon, positive, and teflon, negative closely cancel out the static? My motor is..I think a .5 hp one-thus a beast. I wired a variable current knob to it, so the speed wont be a problem i have the motor glued to a board, then a black round belt running up, to turn a wheel, 7 times more in circumference. So it makes the *new* spindle9one with wheel on it), spin 7 times slower, but also be 7 times stronger | ||
| De Graff Dude Unregistered guest |
NYLON BELT???? HOW...WHAT THE....HUH???? WHERE! | ||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 183 Registered: 12-2004 |
Read the "How does it do that?" section again. The bottom roller is next to the ground brush. Any charge it has will go to ground. To make a nylon belt, cut a nylon tube, or glue or melt the ends of a nylon sheet together. | ||
| joel Unregistered guest |
To DE GRAFF DUDE I used some saran wrap about a strip 1 inch wide. first i made a form out of wood dowel and a 1x6 i put the dowel the right length apart for mine then i cut a peice of the saran wrap roll off and snugly wraped the saran arond the dowels about 5-6 times then i took the whole form put it in the oven with the saran on it and turned on the oven to about 400F then rotated the belt in the oven on the form until the belt got hot and started to stick together then take it out of the oven, let it cool and try it out. GOOD LUCK mine works exelent. Im only 14 | ||
| joel Unregistered guest |
nylon belt?(to complicated) | ||
| joel Unregistered guest |
I also used a old blender it spins very fast and works fine | ||
| khushboo Unregistered guest |
i am khushboo shrivastava, an engineering student.i want to suggest an idea for the working of vande graff generator. as i raed in booksthat it hasa metalic comb in the bottom ,from where it is connected to abattery. my idea is that whather we can supply charge through the combby chargecoming from thundering in the sky,aithough the charge coming is very high but we can use capacitors .SO you can give me advice my path becomes easy in creating this device. you can reach me atmy connectno.(5201379)indore$my email is shrikhushboo@yahoo.com | ||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 197 Registered: 12-2004 |
The charge comes from pulling the rubber belt away from the glass roller. The bottom brushes are simply connected to ground. The top brushes are connected to the spherical collector. The energy comes from moving the belt. | ||
| De Graff dude Unregistered guest |
I need some MASSIVE HELP! I made that one beastly generator earlier mentioned, and the belt and rollers work fine, but get this: -Corona discharge on both ends of top and bottom spindles(steel)(end of pulleys) -Random shocking INSIDE the ABS support column near bottom. -leakage everywhere else? The thing, with a belt of 3" wide theraband, and 3 feet tall, with a rotation speed of bottom spindle at about 2000-3000rpm, CREATES A 3/4 " (18,750 V.)SPARK AT MOST, DUE TO SO MUCH CORONA DISCHARGE! I AM SURE IT COULD EASILY CREATE HALF FOOT TO ONE FOOT SPARKS WITH NO LEAKAGE ANYONE AND EVERYONE PLEASE, LIST AS MANY REASONS AS YOU CAN TO GET MY GENERATOR TO STOP PLAYING POSSUM one thing though, I also fitted the top brush and sphere together very roughly, using fine stell mesh to collect static. ONE MORE THING THAT MIGHT HELP YOUR CONCLUSIONS: I have NO bottom brush, in any way, shape, or form. is that why the sparks are being generated inside ABS, near bottom?) PLEASE HELP ME, AND ANSWER AS MANY OF MY QUESTIONS AS POSSIBLE ASAP. I HAVE SPENT MY LAST 2 WEKKS ON IT, AND NOW IT BARELY WORKS. S.O.S. | ||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 204 Registered: 12-2004 |
Use a bottom brush, connected to ground. Make sure everything is clean and smooth. Use "corona dope" to coat places where you think there is leakage. Use a larger sphere at the top. | ||
| De graff dude Unregistered guest |
Get this-i made my 5th generator, now the third out of 5 to work. It is my best. Its more simple, easy to repair, more powerful (up to 50,000), is quieter, and smaller/more portable. I LOVE IT, except one thing. I actually had to splice the belt this time. It is not thick enough to splice it by thickness, and is about .75 inches wide. I currently use plain electrical tape to connect the ends, and it works quite well. THAT ONE THIS IS: I can never get the belt to stay connected for more than 10 mins, unless it is running(makes it stay together somehow..) HOW CAN I MAKE THIS TINY BELT STAYTOGETHER, WITHOUT MAKING A HUGE MESS??? It is cut at a ....45 to 50 degree angle. help | ||
| Anonymous |
Try sewing it together? | ||
| De graff dude Unregistered guest |
any more ideas(as i write this im about to sew it) more the better(ideas) | ||
| Degraff dude Unregistered guest |
anymore ideas? the sewing worked , and held for about 3-5 days, then broke SHOULD I JUST MELT THE BELT ENDS TOGETHER, SOMEHOW??? | ||
| Anonymous |
If you do melt the ends, you could try a soldering iron. | ||
| Cool dude Unregistered guest |
this van de graff is awesome!!!!!! I think it is really cool to have sparks come to your hand!!!!!!!!!!!!!! | ||
| lysdexia Unregistered guest |
You can do that without a van de Graaff generator. | ||
| Peta Miller-Daraz Unregistered guest |
My son has to build a sound device that makes noise to warn the people in the room next door of a storm that is approaching. He can only use string, paper clips, tin cans, margerine containers, foil plates, straws,paper, masking tape, paper cups, card board and alfoil.Can anyone offer any advice on what to build and how to build it as they have put a limit on the resources to be used. Oh and it is due on the 21st of March 2005. Many Thanks. | ||
| adam (phazei) New member Username: phazei Post Number: 1 Registered: 5-2005 |
A suggestion for the sphere... if you do a google search for steel mirror ball there are a lot of places you can get 16" mirror balls for about $70. They are perfectly spherical and can hold a good charge. I'm posting becuase I made the first half of a vdg a long time ago but i could never get the belt and rollers right. Does anyone have some suggestions on how to make the rollers? Once i have rollers i can just coat them with leather and teflon easily enough. And a belt that won't slip off the rollers, made of a good neutral material. I haven't found anything suitable and I just found this board so I thought I'd ask. Thanks, Adam | ||
| MadScientist (madscientist) Intermediate Member Username: madscientist Post Number: 44 Registered: 4-2005 |
One thing that is commonly overlooked when mechanical problems with the rollers arise, is their shape. Make sure they are slightly convex, so that they will tend to keep the belt on them. Unfortunately, if you are making them from scratch, this is a little easier said than done. | ||
| Jess Salure (Unregistered Guest) Unregistered guest Posted From: 71.7.93.5 |
hey i am building a VDG,its my first but i worked on it for a long time and it is huge, do you have any tips for presenting the VDG to like i know how it works but i couldnt figure out a problem for it and im havin trouble with the aplication? this will help alot thnx so much~jes | ||
| Spark Lover (Unregistered Guest) Unregistered guest Posted From: 74.13.214.126 |
Hey friends, Here are some ideas for materials for VDG that I've tested with success: - Rollers: an old belt sander has some very nice rollers, with the ideal crowning to keep the belt centered, and mounted on good ball bearings! - Belt: Try this: super cheap, high performance and durable: Polyethylene sheet (also called polythene, or painter's drop sheet in hardware stores.) overlap the ends 2 inches and join with clear plastic tape, the kind used to close cardboard boxes. That makes a non-elastic belt, so you have to keep its tension by making a moveable roller. I like to make a ridgid assembly with the lower roller, bearings and the motor, then mount the assembly on plywood board with a door hinge so it can move a couple inches up and down. The weight of the assembly keeps the tension on the belt, there is no need for a spring. -Sphere: IKEA sells stainless steel salad bowls nearly perfect half-sphere, 10'' diameter for $10 ea. Can be assembled together with aluminum tape. - Belt Charging: I admire all your efforts for using friction-charging, but frankly I prefer to use an old flyback HV supply from a broken TV. Much more power and works whatever humidity or not... but requires some electronics knowledge. Possibly could also use HV supply from a bug zapper, or ion air purifier. Just be darn careful if you use anything plugged in AC outlet... or even better, stick to something battery-powered. - Sphere: I have tried to build a virtual sphere by soldering rings of copper wire to make like a big mesh surface... (That was for a 66cm sphere) but it never worked. :o( maybe was better for me after all... any sphere over 27cm diameter can store a dangerous shock -Charge doubler: use a metal top roller. make a first top comb (belt hits it first) connected to the roller. Roller insulated from sphere. Make a second top comb connected to sphere. Roller should become charged polarity same as belt, repelling belt's charge and causing it to lose 2x more charge when it meets the 2nd comb, and leave the sphere with a charge reverse of when it came. This way the charge current is doubled. More charge, more sparks... | ||
| toby bishop (Tsb2225) New member Username: Tsb2225 Post Number: 1 Registered: 4-2008 |
Hi all I've just built a VDG generator from a drink can, rubber band and Lego. I used the Lego plastic for the bottom roller and the same but wrapped firmly in aluminium foil for the top roller. I'm getting 1 inch sparks to a second grounded can, which I think gives about 85,000 volts. I used splayed out multi strand copper wire to make the pickup combs. It worls really well, so it seems that these great machines can be built quite easily with a bit of care. Happy sparking.   | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1891 Registered: 12-2004 |
Very nice! Best use of a Heineken can I've seen yet. ;-) | ||
| Joshua Lim (Vdg) Junior Member Username: Vdg Post Number: 6 Registered: 4-2008 |
Mr. Field, would sticking scotch tape on the rubber band make the performance of the generator better as scotch tape is negative? | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1892 Registered: 12-2004 |
Try it and see. | ||
| Joshua Lim (Vdg) Junior Member Username: Vdg Post Number: 7 Registered: 4-2008 |
Sfield, could baby milk tins generate a large amount of voltage because of their size?(say 50kv) | ||
| Patrick (Firewire) Advanced Member Username: Firewire Post Number: 76 Registered: 12-2007 |
Would a wider rubber band perform better than a thin one? | ||
| toby bishop (Tsb2225) New member Username: Tsb2225 Post Number: 2 Registered: 4-2008 |
Just to let everyone know, our local Asda store (Fareham, UK) are selling 10 inch polished stainless steel spheres as garden ornaments. They are hollow so are light in weight and would make superb top collectors for a VDG. Toby  | ||
| Patrick (Firewire) Advanced Member Username: Firewire Post Number: 77 Registered: 12-2007 |
Hahaha "this is not a toy", maybe not yet...  That's great, round edges would decrease the corona losses made by sharp points. But the photograph doesn't look like a sphere to me, looks more like the underside of a silverware for the kitchen. You could also try to basins welded together to make a nice shperical shape, it has a flat bottom in which you could cut-off, round the sides of the hole with a file or sand paper. you could use that hole to join it with the pipe. I made a a VDG once, but instead of a sphere, I used it to charge a leyden jar instead... | ||
| Jack Faulkner (Unregistered Guest) Unregistered guest Posted From: 81.129.143.207 |
help!!! why do painted aluminum balls stay in the air when placed in avdg generator? school mproject | ||
| Theresa Simmons (Theresa) Senior Member Username: Theresa Post Number: 139 Registered: 1-2008 |
Here's a nice video of the VDG: "http://www.encyclopedia.com/video/mfUMSMKZzZ4-homemade-van-de-graaff-generator.aspx" |
