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Registered Member #3165
Joined: Sat Sept 04 2010, 03:24PM
Location:
Posts: 13
Hi guys! I've now pretty much given up on building a tesla coil, since it's so hard to get hold of an NST in this country. I've decided to have a go at a van der graaf generator though, since this doesn't use an external power source as such. At the moment i have a cotton reel covered in PTFE thread seal tape ,(teflon), for the top roller, and a pyrex test tube ,(glass, obviously), cut short and filled with a shaft bound in tape. The belt will be a strip of material from a pair of tights (i believe you yanks call them pantyhose). Not sure what i will use to drive it yet. I have a motor from an RC car, but it's a bit fast when run straight from the shaft. I might try to get something more slow and steady like a wiper motor. I haven't ruled out hand power either if i can find an appropriate gearing system. This will all be housed in PVC pipe with a polystyrene ball or similar coated in adhesive zinc on top. Does this sound like it could work?
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
This will all be housed in PVC pipe with a polystyrene ball or similar coated in adhesive zinc on top. Does this sound like it could work?
The zink coating must contact the top belt collector and some machine house the top pulley inside the top dome to do this. I wonder if the zink adhesive is smooth and does not present a series of jagged points from which corona will drain the charge before the dome charges up. How are you going to fashion the (nylon) pantihose into a smooth belt? Wont the knot rattle?
Is your belt speed going to be about 3M/second with that motor?
Tesla Coils can be powered from an auto ignition coil too.
Registered Member #3165
Joined: Sat Sept 04 2010, 03:24PM
Location:
Posts: 13
radiotech wrote ...
This will all be housed in PVC pipe with a polystyrene ball or similar coated in adhesive zinc on top. Does this sound like it could work?
The zink coating must contact the top belt collector and some machine house the top pulley inside the top dome to do this. I wonder if the zink adhesive is smooth and does not present a series of jagged points from which corona will drain the charge before the dome charges up. How are you going to fashion the (nylon) pantihose into a smooth belt? Wont the knot rattle?
Is your belt speed going to be about 3M/second with that motor?
Tesla Coils can be powered from an auto ignition coil too.
I plan to wire the zinc coating to the top comb. Hopefully i can find a way to accommodate the top comb in the ball (or whatever else i find). Otherwise it will have to be just below, which will reduce the efficiency a bit. The zinc should be fairly smooth once i rub it down. If i can find a decent metal object i will use that instead, or aluminium foil. I will try to sew the material into a decent belt so there is almost no visible join. Is 3m/s what i should be aiming for? This isn't going to be huge, so that sounds a bit fast. For that i would need about 2200rpm on the motor, which probably isn't possible. I have no idea what the rating on it is.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
I would go with a whimhurst machine. They're easy to make, and you don't need a huge perfectly smooth hollow steel ball. (~$200 for a 20" one)
And what country do you live in? It's possible to make a tesla coil with a few microwave oven transformers in series under oil. You can limit the current with a 500 watt halogen bulb.
hi, theres some interesting stuff on e.s machines on the net , saw one set up using old VINYL records for the rotors ,those things were always static ,there were heaps of products to combat static ,so thats a good use for old LPs. Martin van Marum in 1785 made a generator that put out 750kv , 24 inch arcs using glass rotors. WICKED
Registered Member #3165
Joined: Sat Sept 04 2010, 03:24PM
Location:
Posts: 13
The glass roller shattered when i tried to cut it to size :( I now have a teflon (cotton reel with PTFE tape) roller, and a card/tape roller with parcel tape on the surface (which unusually is very positive, most tapes are more negative). The ball is two 5.5" bowls taped together. The belt is some rubber (probably latex) for physiotherapy. Haven't started on the stand yet, and at the moment i'm using a cordless drill as a temporary motor, but i was getting sparks over 0.5" which wasn't bad considering i haven't degreased the belt or kept anything moisture free at all. I need to work on adjusting my combs, i'm guessing that is the limiting factor at the moment. Pics soon. I also just have a metal bar rather than a smaller ball for discharges which may be limiting the arc length a bit.
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Van Der Graaf Generator
