Back in the 1920s, a young man named Thomas Townsend Brown discovered that if he charged a capacitor with high voltage direct current, the capacitor would exhibit thrust in the direction of the + positive electrode. Off and on for the rest of his life (he died in 1985) he worked on these devices, trying to make a practical propulsion device using this principle. While in college, Brown worked with physicist Paul Biefeld, and the professor's name was added to Brown's when the phenomenon was named "the Biefeld-Brown Effect" (hereafter "B-B").
Basically, a B-B device consists of a small or sharp electrode separated by dielectric material (an insulator, in other words) from a large or blunt electrode. In this form the device is a type of capacitor. When fed high voltage (20,000 volts) DC current, the capacitor will develop thrust leading from the small/sharp electrode and away from the large/blunt electrode. Brown maintained the device thrust toward the positive + pole and away from the negative - pole, but modern experiments have shown the B-B effect works in either polarity. What is important is the electrodes must be differently sized--hence an "asymmetrical capacitor."
A lot of people maintain the B-B effect is electrogravitic; that is, the electrical current acting on the capacitor somehow counters, or interferes with normal gravity. I do not believe this. The effect is clearly the result of excess ions being thrown off the small/sharp electrode, flowing toward the oppositely charged large/blunt electrode. In normal air, the ions pick and charge air ions, adding to the cascade and increasing the thrust. In a vacuum, or under insulating oil, asymmetrical capacitors can still exhibit thrust, though it is usually much weaker. This is because only the ions coming off the forward electrode are present without charged air ions to help push.
This Instructable will describe how to build twin rotary thrusters as a demonstration of the Biefeld-Brown effect. If you prefer to believe this is a form of anti-gravity, you are welcome to do so. My purpose is show you how to build the device, not debate Brown's electrogravitic theories.
New video as of 8/3/2012, showing new type rotors powered by relatively low voltage from a microwave oven transformer:
New video of the thrusters with a different power supply:
Another video showing the ACTs powered by a handcranked Wimshurst machine:
Step 1: Parts you will need
1 polyethylene cutting board, 14 x 17 inches by 3/8ths inch thick
other sizes and materials will work; wood will do if you coat it with insulating varnish
5 feet of 1/2 inch PVC tubing
ordinary hardware store plumbing pipe, white
2 1/2 inch PVC "T" joints
1 1/2 inch PVC 90 degree elbow
5 1/2 inch PVC end caps with flat ends
A lot of pipe caps come with rounded ends. Try to find squared-off, flat caps.
See http://www.creativeshelters.com/fittings/Display-All-PVCFittings.aspx for example
1 1/2 inch PVC plug
10 inches of 1.25 inch (about 40 mm) cardboard tubing
I got this from a roll of holiday wrapping paper. It should be as light -weight as possible without
2 12 oz. aluminum soft drink cans, any brand
2 aluminum discs, 40 mm diameter
Again, these should be as thin as possible to save weight, but be rigid too.
a few square inches of rubber sheet about the thickness of a coin
Foam rubber will do if it's dense
4 rubber appliance "feet" with 1 screw each
about 14 inches of 1/4 inch hardwood dowel
Poplar, basswood, etc.
6 feet of 22 gauge bell wire
6 8/32 brass bolts, each about 1 inch long
1 8/32 brass bolt, about 1.5 inches long
2 aluminum 8/32 threaded spacers, about 1 inch long
1 8/32 washer (brass, aluminum, or steel is OK)
3 knurled brass 8/32 nuts
3 8/32 brass hex nuts
1 resistor, about 4 megaohms
shellac or polyurethane varnish
aluminum HVAC tape
tube cutter, scissors, sharp knife, paper hole punch, a drill with 1/4, 1/16" and 8/32 bits
power supply--see separate page for info