Building a Van de Graaff Generator: Tips and Considerations

[BhutJolokia]

I am building one. Not for school but for personal reasons. Is anyone here familiar or has built one before? I have some questions such as can the collector be any size? The maxium voltage of the collector is generally .8(70000r) with r being the radius of the collector. I was wondering if I could use a 24 to 30 inch collector with a 15kv power supply, or do I need to bump it up?

Scatterd post I apologize.

 

[DrZoidberg]

You can build a VDG any size you want. The voltage depends on the size of the dome but it also depends on the distance between the dome and other nearby conductors. It needs to be high enough above ground. If you want to use a power supply to spray the charge onto the belt the voltage you need is independant of the size of the VDG. 15 kV is more than enough. It should be able to supply a few ten µA.

 

[BhutJolokia]

Thanks man. I'm still looking for a dome but the one I am looking at will provide 750,000 volts. This is, of course, provided it is tall enough. I plan to make it roughly 6 feet tall, so I believe that is tall enough to get a high voltage. I may not reach the 750kv but I will get plenty regardless.

I was told if you increase the current from the power supply to 1mA it helps, even though (with leakage accounted for) you will not need anything near that. That's still to be determined.

Thanks for the reply man, I just wanted to make sure that even with a large enough collector 15kv would be enough to power this thing. (In reality, after the resistor and rectifier it comes out to about 10.5 kv.