| Author | Message | ||
     David S Unregistered guest |
im making the mini Van de Graaff generator im trying to find out what to use for a bottom pully that mounts on the motor im useing a small hair dryer motor on a light dimmer circuit and am useing 1" PVC the problem is that i dont know what plastic item to use for the bottom pulley i want it to be solid so i can drill a hole in the center for the motors' shaft and i also want to cut a notch in the plastic pulley to keet the rubber band in place any ideas on what to get for a plastic pulley | ||
| David S Unregistered guest |
well i jused a piece of wood and covered it with scotch tape the thing worked for about 2 minutes then no more shocks ive been messing with the brushes but still nothing i think ill just upgrade to a really big Van de Graaff i saw a small tabletop one in action and was not happy with the results so im making a 4 foot one any ides on where to get parts? | ||
| David S Unregistered guest |
here is a mod for the small van de graaff i made a plastic pulley and covered it with scotch tape the top pulley is the fuse as in the orgignal plan bugger pipe was used but the pulley was too bug so i had to cut up some 90 bends to make the new motor mount so far i am getting 1 1/2" sparks and the generator charges fast (fast = a shock every 1/2 second) here is a pic of it  | ||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 278 Registered: 12-2004 |
Nice! | ||
| Anonymous |
i am interested in making a small table top van de graaff generator, but have no plans, so if you have any please post them here and i will check back, lots of detail if possible. | ||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 381 Registered: 12-2004 |
The plans are in the "Fun with High Voltage" section. | ||
| Kevin H Unregistered guest |
Ok...here's the deal...i haven't yet assembled my van de graaff, but i was having trouble when I temporarily assembled it to test it...the rubber band kept moving around so I used hot glue to make little rails on the edges of the glass fuse tube...when I upgraded to a wider but smaller rubber band, I found that it rides up on the little rails and wants to stay there...since these are at the edge and not the center, I'm going to melt the original rails and replace them with a central one...but here's the dilemma: I don't know what effect the hot glue will have on the generation of static...will it still generate static even if the rubber band does not touch the glass but rides on the rail? I really want this to work and have already had one disappointment: after I had finally soldered the wires to the motor, I tested it and it didn't work (it had worked the day before)!!!GRRR I took it apart but im just going to replace it with a remote control car motor (i think probably 6 volts [it had a 6 volt battery])which was used for the steering of the front wheels. Its definitly not flimsy as the motor that died on me (which came from a 2 AA battery powered fan), but I want to know whether a 9 volt battery will kill the battery (and approx. how long) b/c the 2 AA's definitly aren't cutting it... Please help!!! | ||
| Kevin H Unregistered guest |
Oh, one more thing... If i place a grounded object near the can (or just the wire that should go to the can) will it make a constant lightning/spark discharge like tesla coils? What about putting the bottom brush near the can instead of grounding it...won't there be sparks jumping from the can to the wire? I just want to be able to see a CONSTANT spark (or lightning-ish thing) b/c I want this to be as visually appealing as possible and being able to see the static power without getting shocked (by touching it)...I know that it will make sparks to a grounded object every so often, but is it possible from a generator this size to achieve the voltage necessary to generate a constant spark? Please respond ASAP...I'm backlogged in work and would like to know exactly what to do come the weekend (or any free time)... | ||
| Kevin H Unregistered guest |
Sorry aobut all these multiple posts...but...Thanks. | ||
| Jonathan Grova (Jonathan8388) New member Username: Jonathan8388 Post Number: 1 Registered: 5-2005 |
i have been using my van de graff generator for a while now and i must say that it is working well(except for the fuses breaking). i am able to get 3/4 inch sparks to my finger at the rate of about 1 spark per second. i was looking at the messageboards on your website yesterday and i came across someone who made a pulley for the motor of the van de graff generator and was able to get 1 1/2 inch sparks at the rade of a 1/2 a second each spark! i then tried to make my own pulley by wrapping multiple layers of scotch tape around the shaft of the motor, and this improved it a little bit and gave me 1 inch sparks at the rate of 1spark per 1/2 a second! my question is: why would making a pulley around the motor shaft improve the performance of my generator? would there be a different material instead of tape that i could use for the pulley to improve the generator more? | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 429 Registered: 12-2004 |
Looking at the triboelectric series in the VDG section, I would say that glass pulleys and a silicone rubber band might get the best performance. You could try making the band by cutting a loop from a nylon stocking and then coating it inside and out with a thick layer of silicone caulking from the hardware store. Or wrap some waxed paper around a jar, and then paint a band of silicone rubber around it, and apply another layer of waxed paper over that, to make both surfaces smooth. When it dries, you have a silicone rubber band. Once you have a silicone rubber or teflon band, you might try nylon pulleys. Then you wont have fuses that break. PVC pulleys and a nylon band might also do well. Or, if you want the same level of performance but without breaking fuses, try a rubber band and PVC pulleys. The triboelectric series is your guide to optimizing the performance. | ||
| Jonathan Grova (Jonathan8388) New member Username: Jonathan8388 Post Number: 2 Registered: 5-2005 |
i have been using my van de graff generator for a while now and i must say that it is working well(except for the fuses breaking). i am able to get 3/4 inch sparks to my finger at the rate of about 1 spark per second. i was looking at the messageboards on your website yesterday and i came across someone who made a pulley for the motor of the van de graff generator and was able to get 1 1/2 inch sparks at the rade of a 1/2 a second each spark! i then tried to make my own pulley by wrapping multiple layers of scotch tape around the shaft of the motor, and this improved the performance of the generator and gave me 1 inch sparks at the rate of 1spark per 1/2 a second! my question is: why would making a pulley around the motor shaft improve the performance of my generator? would there be a different material instead of tape that i could use for the pulley to improve the generator more? | ||
| Jonathan Grova (Jonathan8388) New member Username: Jonathan8388 Post Number: 3 Registered: 5-2005 |
oops, sorry for the double post. i tried to delete it, but it wont let me! my question is would the pulley that i made around the motor be the cause in the better performance of my generator? also, how could i make a nylon pulley? would bigger pulleys give better performance? also what material would you choose as the BEST material for the pulley ON THE MOTOR? sorry fotr all of the questions. answers would be greatly appreciated (Message edited by jonathan8388 on May 21, 2005) | ||
| Anonymous |
Does a Van de Graff generator have any useful purpose besides being a toy? I've heard that they produce high voltage at extremely low current, making the power generated very small (too small to do anything useful with). Is that true? I also read they are viewed as a constant current source if you were to connect them to a load. Is that also true? On a side note, I was thinking... would it be possible to connect a wire with a spark gap to the metal top (in this case a can) and connect the other side of the spark gap to a capacitor. So that when the charge gets to a certain point it discharges into the capacitor and in effect charges the capacitor. Then you could use another spark gap to discharge the capacitor into a load when the capacitor reaches a certain value. This might make the generator more useful. Especially, if instead of using an electric motor, you used a small wind mill or water wheel... Does this seem possible? Thanks | ||
| Bill beaty Unregistered guest Posted From: 128.95.172.173 |
> Does a Van de Graff generator have any useful purpose besides being a toy? The first large VDG built by Robert VandeGraaf was used to power an atom smasher at MIT. Here's a drawing: http://www.mos.org/sln/toe/diagrams/rhcutaway.jpeg Today VDGs are used in physics lab, go search on "Pelletron" http://www.google.com/search?q=pelletron+voltage > I've heard that they produce high voltage at extremely low > current, making the power generated very small (too small to > do anything useful with). Is that true? A commercial VDG such as used in a classroom can put out 250,000 volts at a few millionths of an ampere. Wattage is volts times amps, and 250KV times 10 uA gives 2.5 watts. Two and a half watts would light a dim flashlight bulb, or light a whole bunch of LEDs, or it could operate the electric motor in a toy car. But first you'd have to figure out how to step the voltage down about fifty thousand times! > I also read they are viewed as a constant current source if > you were to connect them to a load. Is that also true? Yes, the current from the VDG is always about the same, but the voltage changes drastically depending on the load. If you put some sharp needles on the top of your VDG, the current will be the same, but the voltage will decrease greatly. | ||
| Justin (Commander_bob) New member Username: Commander_bob Post Number: 3 Registered: 10-2006 |
I just made my VDG and I did it as it said in the High Votage section but it did not work. I was wondering if it mattered it the inside of the can was a little wet or that the rubber band rides on the side of the motor? Thanks | ||
| Justin (Commander_bob) Junior Member Username: Commander_bob Post Number: 4 Registered: 10-2006 |
Also for the bottom pully I used electical tape and a metal screw head so it would not fall off. If this is a problem than what else could I use? Thank You | ||
| Justin (Commander_bob) Junior Member Username: Commander_bob Post Number: 5 Registered: 10-2006 |
I decided to upgrade to a larger VDG after making the desk top one. I get about 2" sparks about two every second. I used PVC 1" attached to the motor and a very large rubber band from office depo I think. For the top roller I used 3 nylon spacers. Two large ones are on each side of a smaller one so the rubber band stays in the middle. For the can I got a lagrge Foster's. The motor I got from a old fan from a gradge sale for 50 cents. Here is a picture.  | ||
| mike (Mike11298) New member Username: Mike11298 Post Number: 1 Registered: 10-2006 |
hi all, just looking for some ideas in finding or making a nylon pulley. Any help is greatly appreciated - Thank you! | ||
| surendra murthy.c (Science_boy) Junior Member Username: Science_boy Post Number: 5 Registered: 6-2007 |
my vdg was a success, but tell me whether the brushes should touch the rubber band or not. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1760 Registered: 12-2004 |
Not. Please don't post the same question in three places. Once is enough. We see them all. | ||
| surendra murthy.c (Science_boy) Junior Member Username: Science_boy Post Number: 7 Registered: 6-2007 |
i am sorry, i needed a quick reply.anyway thanks my vdg works better today.i connected it to the franklin bell as mentioned in the plan but it did not work.what are the possible problems that may be taking place | ||
| surendra murthy.c (Science_boy) Junior Member Username: Science_boy Post Number: 9 Registered: 6-2007 |
will the rotatory high voltage motor work on the vdg? | ||
| Joshua Lim (Vdg) New member Username: Vdg Post Number: 1 Registered: 4-2008 |
Mr. Field, How does a electron gun work? I am thinking of making one at home to collect high voltage. If you concentrate the beam of electrons with some magnets, would you get a spark? | ||
| Joshua Lim (Vdg) New member Username: Vdg Post Number: 2 Registered: 4-2008 |
Sorry for posting in the vdg section, should have posted somewhere else. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1895 Registered: 12-2004 |
"http://www.google.com/search?q=electron+gun". | ||
| Aaron (Sciencenerd) New member Username: Sciencenerd Post Number: 1 Registered: 8-2010 |
could i use pvc rubber as the belt? thanks | ||
| Patrick (Firewire) Senior Member Username: Firewire Post Number: 145 Registered: 12-2007 |
I am using those thick rubber bands used in slingshots, is it has almost the same width of the glass fuse I have. also. Also, the issue about the rubberband moving left or right, or trying to stay at one side is due to a mis-aligned axel for the fuse. |
