Problems Building a Van De Graaff Generator

In summary, the conversation is about building a small Van de Graaff generator based on online designs, with the user experiencing difficulties in creating arcs. They have tried various combinations of materials for each part and have measured potential differences between the cups using a multimeter. Suggestions are given for improving the design, such as using a metal sphere for the top and ensuring all surfaces are smooth and clean. The importance of using a good non-conductive material for the column is also mentioned. The user has measured a current of ~100 uA with a cheap commercial machine.
  • #1
AniV
15
1
I have been trying to build a small Van de Graaff generator based on the designs found here: http://rimstar.org/equip/build_make_van_de_graaff.htm

Unfortunately I haven't been having much luck. How can I improve it?
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13692923_587926388052702_8808151424123490542_o.jpg

The body was 3D printed using PLA plastic.
It encloses the rubber band belt completely.
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13735540_587926381386036_2540663988244643720_o.jpg

The bottom motorized roller is made PCV electrical tape and a slice of PVC tubing:
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13698065_587926361386038_7472904692042366737_o.jpg

The top roller is made of nylon thread:
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13680297_587926378052703_6114147970296557842_o.jpg

The rubber band is one of those used to hold together vegetables from the supermarket.
The configuration is shows below.

https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13723871_587926374719370_906130344536881567_o.jpg


I have used many combinations of many materials for each part. I have tried using steel drinking cups and silver cups for the metal domes. I have tired thick, and thin rubber bands fro the belt, as well as balloon rubber for the belt. I also tried multiple materials for the motorized roller, including only teflon tape, only PCV electrical tape, and the current design with the PCV piping.

The generator does work, as I have measured potential differences between the two cups using a multimeter, but it doesn't create arcs. Do I need to insulate the metal better?
 
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  • #2
Is the top pulley shaft riding on some sort of bushing or bearing? Would/could a vacuum cleaner drive belt be used in place of the rubber band? I'm not sure what the brush/pickup consists of but that might be crucial to generating more power, These are just thoughts that initially crossed my mind, I imagine someone with more knowledge will be giving an opinion before long. As an afterthought this might have been better placed in "electrical engineering" thread, I'm curious to see how this works out. Something along the lines of a flag pole cap ball might be the shortest route to your dome problem.
 
  • #3
AniV said:
I have been trying to build a small Van de Graaff generator based on the designs found here: http://rimstar.org/equip/build_make_van_de_graaff.htm

Unfortunately I haven't been having much luck. How can I improve it?
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13692923_587926388052702_8808151424123490542_o.jpg

The body was 3D printed using PLA plastic.
It encloses the rubber band belt completely.
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13735540_587926381386036_2540663988244643720_o.jpg

The bottom motorized roller is made PCV electrical tape and a slice of PVC tubing:
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13698065_587926361386038_7472904692042366737_o.jpg

The top roller is made of nylon thread:
https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13680297_587926378052703_6114147970296557842_o.jpg

The rubber band is one of those used to hold together vegetables from the supermarket.
The configuration is shows below.

https://scontent.fsnc1-1.fna.fbcdn.net/t31.0-8/13723871_587926374719370_906130344536881567_o.jpgI have used many combinations of many materials for each part. I have tried using steel drinking cups and silver cups for the metal domes. I have tired thick, and thin rubber bands fro the belt, as well as balloon rubber for the belt. I also tried multiple materials for the motorized roller, including only teflon tape, only PCV electrical tape, and the current design with the PCV piping.

The generator does work, as I have measured potential differences between the two cups using a multimeter, but it doesn't create arcs. Do I need to insulate the metal better?
Do you have a metal sphere for the top. This seems important. The machine I use has a metal top roller and also some thin metal pick up brushes. I think the two rollers must be different material according to the electro static series. My roller is inside the top sphere.
With a commercial machine I find it is very important that there is a perfect smooth and clean surface everywhere, and I dry everything with a hair dryer. It is also possible the belt is leaky.
 
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  • #4
What is that material for the column? It has to be a really good non-conductor or all your charge will bleed away. For the design you show there has to be a contact potential difference between the belt-lower pulley and the belt-upper pulley. Since the material is the same for the belt the pulleys must be made of different materials. The cheep one of these I bought generates ~100 uA of current which one may measure with an multimeter.
 

1. How does a Van De Graaff Generator work?

A Van De Graaff Generator is a device that uses static electricity to create a high-voltage electric field. It consists of a metal sphere or dome on top of a stand, a belt of insulating material, and a motor. The motor turns the belt, which rubs against a metal comb and charges the dome with positive static electricity. As the charge builds up, it creates a high-voltage electric field around the dome, and any nearby objects or people will experience a shock when they touch it.

2. Why is my Van De Graaff Generator not producing sparks?

There are a few possible reasons for this. One common issue is that the belt might be worn out or not making good contact with the metal comb, so it is not generating enough charge. Cleaning the belt and comb with rubbing alcohol or replacing the belt could help. Another possibility is that the humidity in the air is too high, which can reduce the effectiveness of the generator. In this case, you may need to use a dehumidifier or wait for dryer weather to see sparks.

3. How do I safely operate a Van De Graaff Generator?

It is essential to take proper precautions when using a Van De Graaff Generator to avoid electric shocks. First, make sure to have a good grounding system in place, such as a metal rod driven into the ground. Also, wear rubber gloves and shoes and avoid touching any metal parts of the generator while it is in use. Finally, keep the generator away from any flammable materials and always turn it off and unplug it before making any adjustments or repairs.

4. Can I build my own Van De Graaff Generator?

Yes, it is possible to build a simple Van De Graaff Generator using household items and basic tools. However, it can be challenging to achieve high voltages and consistent sparks without the proper materials and knowledge. It is recommended to follow a reliable guide or seek help from an experienced builder to ensure safety and success. Alternatively, you can purchase a pre-made Van De Graaff Generator kit.

5. What are some common problems when building a Van De Graaff Generator?

One common issue is that the belt may slip or not make sufficient contact with the comb, resulting in a weak or nonexistent charge. This can be remedied by adjusting the belt tension or using a different type of belt material. Another problem could be insufficient grounding, which can lead to shocks and safety hazards. It is crucial to have a good grounding system in place to prevent this. Other potential issues could include damaged or faulty components, such as the motor or comb, which may need to be replaced.

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