The Van de Graaff generator is a high-voltage device capable of producing multi-million volt discharges.
Known for its ability to create sparks and raise hair on end, it operates using mechanical friction.
The mini version can produce over 40,000 volts from just two AA batteries and fits in the palm of your hand.
Key Features of the Mini Van de Graaff Generator
Produces sparks of 0.5 to 1 inch in length (dependent on humidity).
Safe to touch.
Originally developed for splitting the atom utilizing the triboelectric effect to move electrons.
Materials Needed
4.5 inch section of 1.5 inch acrylic tubing
0.5 inch wide Teflon bar stock
1 inch nylon spacers (important for insulation)
3 volt motor
1.5 inch steel brace for motor mount
2 acrylic disks (3-4 inches across)
3 machine screws (at least 1.5 inches long)
1 brass or steel rod
1 wide rubber band
1 metal sphere
Build Instructions
Base Assembly
Prepare Acrylic Disks: Drill four holes in each disk at 120 degrees apart, 0.25 inches from the edge, plus a center hole (1/16 inches).
Connect Disks: Place nylon spacers between the disks and secure them with bolts and nuts.
Lower Roller and Motor
Teflon Rod: Cut it to a half-inch and drill a precise hole for the motor axle.
Motor Mounting: Fit the roller onto the motor and drill holes for mounting using the steel brace as a stencil.
Insulating Tower and Upper Roller
Acrylic Tube: Drill holes for the rod and ensure ends are square.
Rod Installation: Pass the rod through the tube, adding nylon spacers for stability.
Epoxy Application: Secure the assembled tower in place ensuring alignment of rollers.
Ground Brush Installation
Lower Brush: Spread stranded wire into a fan shape, solder onto a wire connector, and bolt into place.
Upper Brush: Construct using aluminum foil tape cut into strands, ensuring it does not touch the rubber band.
Electrode Assembly
Use a metal sphere with a 1.5 inch hole at the base, secure with an O-ring.
Attach the upper brush inside the electrode.
Rubber Band Installation
Stretch and wrap the rubber band over the lower roller.
Electrical Ground
Create a counterpoise from aluminum foil tape and connect the battery holder to the motor.
Operation
Activate the generator using a switch; sparks should produce within seconds.
If sparks do not appear, reduce humidity by warming the device with a hair dryer.
Applications
Demonstrates static electricity principles: like charges repel, opposite charges attract.
Example: Christmas tinsel can be used to show repulsion and attraction to nearby hands.
Maintenance
Requires minimal maintenance, mainly replacing the rubber band belt over time.
Additional Resources
Related projects include a 3 volt Tesla coil and mini desktop lightning tower (links provided in the video description).
Conclusion
The mini Van de Graaff generator is an engaging experiment showcasing electrical principles, suitable for educational demonstrations and personal enjoyment.