Mini Van de Graaff Generator DIY Guide

Introduction

• The Van de Graaff generator is a well-known high voltage device, capable of producing multi-million volt discharges.
• It works on the principle of mechanical friction to build up a charge and is often used in demonstrations to create sparks and static electricity.
• This guide focuses on a DIY version that can produce over 40,000 volts, powered by two AA batteries.

Key Features of the Mini Generator

• Size: Fits in the palm of your hand.
• Voltage: Produces sparks of half an inch to an inch long.
• Safety: Safe to touch and can make hair stand on end.
• Principle: Uses the triboelectric effect to move electrons.

Materials Required

• Acrylic Tubing: 4.5 inches section of 1.5 inch diameter.

• Teflon Bar Stock: Half inch wide.

• Nylon Spacers: 1 inch.

• 3 Volt Motor

• Steel Brace: 1.5 inches.

• Acrylic Disks: 3-4 inches in diameter (2 pieces).

• Machine Screws: At least 1.5 inches long (3 pieces).

• Brass or Steel Rod

• Wide Rubber Band

• Metal Sphere

• Note: Links to most parts can be found in the video description.

Building the Base

1. Prepare Acrylic Disks:
   • Drill four holes in each disk, 120 degrees apart from each other, and a center hole of 1/16 inch.
   • Peel protective coating off the disks.
2. Assemble Base:
   • Place nylon spacers between the holes and connect with bolts.
   • Tighten down all connections to complete the base.

Lower Roller and Motor

1. Teflon Rod:
   • Cut to half inch and drill a hole for the motor axle.
   • Bevel the edges.
2. Assemble Motor:
   • Fit the roller on the motor and secure it with bolts, ensuring stability.

Insulating Tower and Upper Roller

1. Prepare Acrylic Tube:
   • Drill holes for the rod, ensuring they are opposite and exactly 1/4 inch from the edge.
2. Assemble Tower:
   • Insert a nylon spacer and secure the rod through the acrylic.
   • Use epoxy cement to fix the tower in place.

Ground Brush Assembly

1. Lower Brush:
   • Spread stranded wire to create a fan shape and solder to a wire connector.
   • Install the lower brush in the base.
2. Upper Brush and Electrode:
   • Use a specialized metal sphere or a soda can.
   • Cut an opening for the rubber o-ring and securely attach the upper brush.

Installing the Rubber Band

1. Rubber Band Setup:
   • Remove the upper roller to install the rubber band.
   • Stretch it down the tube and wrap it around the lower roller.

Final Setup

1. Electrical Ground:
   • Create a counterpoise with aluminum foil tape.
   • Add a battery holder and connect to the motor with a switch.
2. Operation:
   • With the switch, the generator produces static electricity and sparks.
   • If sparks don't appear, warm up the device with a hair dryer.

Demonstrations

• The mini Van de Graaff generator can show static electricity effects, such as charge repulsion and attraction.
• Example: Tinsel taped to the electrode stands upright when the device is on due to like charges repelling.

Maintenance and Conclusion

• Minimal maintenance required; only the rubber band needs replacement over time.
• Touted as a fun and educational project, part of a series including a 3-volt Tesla coil.

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