Van der graaf generator and tesla coil

[mark68]

Hello peoples.
Im attempting to build a van der graaf generator and a small tesla coil. Hopefully I have come to the right place for help.
Firstly I'll start with van der graaf generator. I am going to use pvc lower roller (negative charge) and nylon upper roller (positive). any suggestions on better materials for rollers for better results.? also i was wondering if a woven polyester strap as used for tie down straps on trucks etc will work as a belt?
I am trying my hardest not to buy anything for generator build and would love to make it from found / scavanged items , re the strap question.
Thanks

 

[Archosaur]

Sorry if I underestimate your current knowledge. I'm going to explain things fairly simply.

When looking for materials to make a van der graaf generator out of, there are two main things to consider:

The first is "electron affinity".

"Electron affinity" is a property of a material that is basically how much it "likes" electrons.
Rubber has a higher electron affinity than your hair, so, when you rub a (neutrally charged) rubber balloon on your (neuterally charged) head, the balloon takes electrons from your hair. There is now a charge "separated" between the balloon and your head. The balloon has a negative charge and your hair has an equal positive charge. Rubbing two materials together to separate a charge is called the "triboelectric effect". The greater the difference in electron affinities of two materials, the easier it will be to separate a charge by rubbing them. If material A "really likes electrons" and another "kinda likes electrons", you will be able to separate a charge between them by rubbing them, but not as easily as you would with material A and a material that "frackin' hates electrons".

A van der graaf generators work because of the "triboelectric effect".
A triboelectric series is a list of materials in order of their electron affinities. So, the further apart materials are on the list, the easier it is to separate a charge by rubbing them, so the better they will be for a van der graaf generator.

Here is a triboelectric series:

http://simcostaticcontroljournal.com/RFID/figure%202.jpg

See how far apart human hair and rubber are? That's why rubbing a balloon on your head is so effective at separating a charge.

The second thing to consider is "conductivity" which is a property of a material that describes how easy it is for electrons to flow through it.

A van der graff generator has three main parts: a ball for collecting charge, a ground to "harvest" the charge, and a belt to take the charge from the ground to the ball.
If the belt is too good a conductor, the charge won't stay on the ball, it will just escape through the belt and into the ground.
If the ball is to poor a conductor, the charge won't arc to your finger, which is what I assume you are doing this for :)

Anyway, good luck with your building!

 

[astrokreng]

Hello! It's great to hear that you are interested in building a van der graaf generator and a small tesla coil. Both of these devices use high voltage electricity to create interesting effects and are commonly used in science demonstrations and experiments.

As for your question about materials for the rollers of the van der graaf generator, PVC and nylon are commonly used and should work well. However, you may also want to consider using materials with better insulating properties, such as acrylic or glass, to minimize any potential leakage of charge. As for the belt, a woven polyester strap may work, but it may also create friction and wear out quickly. It's worth experimenting with, but if possible, it may be better to use a rubber or silicone belt specifically designed for this purpose.

It's admirable that you are trying to build these devices using found or scavenged materials. Just be sure to take proper safety precautions and carefully test and monitor your devices as you build them. Good luck with your projects!