Introduction: Asymmetrical Capacitor Thrusters: the Biefeld-Brown Effect

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

Here is a list of the materials you will need to build the thrusters:

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 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
     compromising strength

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

Super glue

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

Step 2: The Capacitors

Asymmetrical capacitors are simple devices. First cut two lengths of 40mm cardboard tubing, 3.5 inches long. With a common hole punch, punch one hole in each tube as close to the mid-point as your punch can reach. It may not be at the balance point, but it won't matter.

Next coat the tubes thoroughly inside and out with shellac or polyurethane varnish. Let dry until completely hard.

Using the end of the tube closest to the punched hole, trace a circle around the tube on a piece of thin rubber or foam rubber. Cut this out carefully and glue over the open end of the tube nearest the punched hole. 

Take an empty, clean, and dry soft drink can. With a sharp pair of scissors or an X-acto knife, cut off both ends. Cut the resulting tube of aluminum in a straight line along the long axis, making a single rectangle of aluminum. Flatten this out gently and draw two parallel lines 2.25 inches apart. Cut the aluminum along both lines. You'll end up with a rectangle of curled aluminum 2.25 inches long. Trim to 4.5 inches wide. 

Wrap the aluminum around the cardboard tube snugly. Apply Super Glue to the inside edge of the metal cylinder. You can use clothes pins or other small clamps to keep the aluminum in place till the glue sets. When the glue is dry, cut a piece of aluminum duct tape 2.25 inches long and 1/2 an inch wide. Put this over the outside of the glued joint and smooth it down.

Repeat these steps to make a second thruster.

Take the two 40mm aluminum disks (I used ID tags, no hole). Glue these over the rubber end pieces with Super Glue. Center the disks carefully and allow to dry. 

If your aluminum cylinders are carefully made, they should slip on over the cardboard tubes, yet be tight enough to stay in place.

The capacitors are done. Set them aside until later.

Step 3: The Thruster Base and Frame

At the corners of your cutting board drill short pilot holes and install the four rubber appliance "feet". Be sure not to drill all the way through the board. If you do, fill the hole from the top with clear silicone sealant, otherwise you may get arcing to the exposed screw points.

Turn the board over. Using a ruler, find the exact center of the board. The simplest way to do this is to measure from corner to corner. Where the two lines intersect is the center of the board. Drill a 8/32 hole all the way through the board. 

Chose two corners on opposite diagonals. Just inside from the rubber feet on each corner drill a 8/32 hole through the board. Take two 1/2 PVC flat headed pipe caps. Drill a 8/32 holes in the center of the cap (the center is often indicated by a small dot left over from the casting process). Put a 1 inch long 8/32 bolt upward through each hole in the cutting board. Push the bolts through the holes in the caps. The open end of the cap should face upward. Put a 8/32 nut on each bolt and tighten. Don't over tighten and crack the PVC.

Put a 1 inch 8/32 brass bolt through the hole in the center of the cutting board, pointing up. Put a washer over the bolt and screw on one inch-long threaded aluminum spacer. Tighten finger tight. 

Cut two pieces of 1/2 inch PVC 9.5 inches long. Insert these in the pipe caps using a twisting motion. Don't use PVC cement! Next take your 90 degree elbow and two T joints. Cut two pieces of 1/2 inch tubing, each 8 inches long. Put the elbow on one, a T in the middle, and the other T at the other end. Take your 1/2 PVC plug and drill a 8/32 hole in the center of the plug. Insert a brass 1 inch 8/32 bolt down through the cap.

Cut about 15 inches of single strand 22 gauge bell wire. Strip about an inch of insulation off each end. Wrap one end tightly around the bolt inside the plug. Add a washer on the outside of the cap, then screw on your other aluminum spacer. The  wire should be firmly attached to the bolt at this point. Feed the wire through the PVC tubing toward the second T joint. Insert the plug with metal parts into the center T joint. Press in until it fits tightly.

To the outside T joint fit a short length (about 1.25 inches)  of 1/2 PVC tubing. Get a flat 1/2 inch pipe cap and drill the center for another 8/32 bolt. Thread a knurled 8/32 nut onto the 1.5 inch brass 8/32 bolts. Put the 8/32 bolt into the cap hole from the outside. Wrap the stripped end of the 22 gauge bell wire around the bolt. Fit a 8/32 nut and tighten the nut and knurled nut together, leaving about an inch of bolt protruding from the cap. 

(The efficiency of the thruster can be increased by using better insulated, high voltage rated wire to connect the upper electrode to the top spindle connection. Where can you get HV wire? Salvage it from old microwave ovens--that's what I do.)

Set the frame and top tubing aside and proceed to the next step.

Step 4: The Spindle

This is trickiest part of the assembly. I will give measurements from my model, but you may have to fiddle with them to get yours to fit and spin freely. 

Cut a piece of 1/2 inch PVC tubing 6 inches long. By hand or with a drill press, drill a 1/4 hole at the exact middle of the tube. Be sure the hole is centered horizontally as well as longitudinally!  The thrusters must be balanced in order to spin easily.

Drill 8/32 holes into two flat PVC 1/2 inch pipe caps. Take care these are centered as best as you can. Put 8/32 brass bolts through the holes from the inside and thread on a knurled brass nut on each. Leave loose for now. 

These bolts will not spin in the 8/32 aluminum spacers as is. Using a file, or emery cloth, try to wear down the exposed threads on the bolts. You don't have to smooth them out completely, just ease them enough they will turn in the spacers without binding.

Cut your 1/4 hardwood dowel to 13 inches. Slip this through the hole in the spindle. Make sure it's centered on the spindle tube. It should be a snug slip-fit. If it's too loose, you may have to put a drop of Superglue on the joint after you center the dowel on the spindle. 

Just below the top and bottom caps drill small (1/16th inch) holes on both sides of the spindle aligned with the dowel. Cut two lengths of 22 gauge bell wire 16 to 17 inches long. Strip all four ends 3/4 of an inch. In the very center of the wires, carefully strip off 1 inch of insulation, leaving bare wire in the middle. Make a loop in this bare section. Fit the loop over the head of one of the bolt in the pipe cap. Pull tight, then snug the knurled nut on the outside, trapping the wire against the cap. Repeat this process on the second cap. Feed the wire into the spindle and out again through the 1/16th holes, top and bottom. Press the caps in place. 

Put a drop of glue or silicone cement on each end of the dowel. Carefully slip the dowels into the 1/4 holes punched in the thrusters. MAKE SURE THE THRUSTERS FACE THE RIGHT WAY--the flat discs of BOTH capacitors must be placed to "chase" each other around the spindle. If you put them one facing the other the thrust will cancel out and the device will not move. It doesn't matter if the device turns clockwise or counter-clockwise.

Push the dowels all the way through to the opposite side of the thruster and hold there until the glue sets. Make sure the thruster units are level! Thrust will be wasted if the capacitors are canted up or down. 

When the spindle assembly is dry, insert the bottom smoothed bolt into the aluminum spacer mounted on the cutting board. Fit the top assembly to the two upright tubes, taking care to fit the top spacer over the smoothed brass bolt sticking out of the top of the spindle. Press the top assemble int place. Check that the spindle turns freely. If it doesn't, apply graphite (not oil!) to the spacers and adjust how much the top assembly presses down on the spindle. 

Cut 3/4 inch squares of aluminum duct tape. The upper wire should reach the aluminum disk glued to the front of each capacitor. Tape the bare ends of the wire to the disks. The lower wire must be taped to the long aluminum cylinders at the rear of the thruster. Smooth the tape down firmly.

Step 5: Power Supplies

The Biefeld-Brown Effect requires direct current. You may find sites on the Net or books that say you can use AC, but trust me, AC won't work. Neon sign transformers, oil burner ignition modules, etc. won't work unless rectified into DC. There is an easy DC power supply you can use.

Your best and easiest choice is an old TV set or computer monitor, the heavy, blocky kind with a cathode ray picture tube. These are usually called "CRT monitors." Computer monitors are often available for free as more and more people convert to flat LCD type screens. (I once called a person in my town who wanted to give away a free CRT monitor. She was so happy to get rid of it she delivered it to my house!)

CRTs contain high voltage capacitors that can hold a powerful charge for a long time! Be careful! If you pick up an old CRT, leave it unplugged for several days before you try to tinker with it. Even then, watch out! It takes very little effort to convert a CRT into a high voltage DC power supply, but BE CAREFUL!

You'll need a couple of cables, maybe 24 inches or more long. They must be able to handle high voltage. I salvage HV cable from microwave ovens, etc. but you can make your own by using heavy duty stranded 10 or 12 gauge house wire and slipping it into vinyl or silicone tubing. I pushed 10 gauge house wire into vinyl aquarium tubing. 

Attach small alligator clips to each end of your HV cables. 

Next, turn the CRT screen-down. You don't want to scratch or crack the picture tube (it may explode), so inverting the monitor on a pad or old towel is a good idea. Remove the CRT's rear cabinet. You might have to cut off the data cable first, as some monitors have the cable molded in so they can't be detached. You can also discard the pedestal if it is in the way.

Once the cabinet is off, BE CAREFUL. Look for a thick cable ending in a black suction cup. This will be attached to the picture tube somewhere. Gently pry the suction cup off. Inside will be connectors used to channel high voltage from the monitor power supply to the picture tube. This will be your positive (+) HV connection.

Look around the other side of the picture tube. You should see a strand of bare wire running around the front edge of the tube. This is your negative (-) or ground connection. Clip one alligator clip to the + suction cup connection. Take the other HV cable and clip one end to the - ground wire.

You can cut small holes in the plastic cabinet that allow you to feed your HV cables out. Once you have your cables through the cabinet, put it back on the monitor and screw it back in place.

To operate the asymmetrical capacitor thrusters, set them on a large table or cleared floor area. Put your upside down CRT as far away as your cables will allow. Connect the positive CRT cable to the brass bolt on the top of the thruster frame. Clip the negative cable to the spacer on the bottom of the spindle. Be sure the cables don't touch or interfere with the turning of the thrusters.

Before you power up, make sure the CRT switch is on. It's best if you can plug the CRT into a variac or other isolation transformer. This gives you control of the input voltage and a safe on/off switch. If you don't have a variac, try to use a wall plug controlled by a wall switch.

KEEP WELL BACK from the thrusters and monitor while it's turned on. A CRT power supply can produce 20-30,000 volts, depending on the size of the monitor. That much DC can really hurt you! It can also jump a surprisingly long way from exposed metal connections to you. So stay back!

OK, so you're plugged in. You're well back from the thrusters. Hit the switch! Now what happens?

Step 6: Troubleshooting

If you've led a clean life and followed every direction in this Instructable, your Biefeld-Brown thrusters should work right off. When you power up, there's a slight delay, then you'll hear a hissing coming from the capacitors. The thrusters will start to turn, slowly at first, then with increasing speed until they reach the maximum potential of your device. The thrusters I built reach a top speed of 46 RPM when powered by an old Dell CRT I estimate is putting out 27,000 volts. Thrusters work best on a level surface, in dry, cool air.

Suppose you flip your switch and nothing happens? Switch off and check your connections. Most likely your CRT is not working. They can short out, and when they do, they're dead. Keep your cables and connections tight and widely separated at all times.

Suppose you get hissing, but no rotation? Your spindle is probably binding. Switch off the power and check the pressure of the frame top against the spindles. Try the brass spindle posts. Do they turn freely, or do the threads still bind? You may have to buff the threads down a little more. Lubricate the spacers with a little powdered graphite (usually sold as lock lubricant). Don't use oil! Oil is an insulator. It will interfere with the transfer of power through the brass screws.

Suppose you get rotation, but it is very slow? Your power supply may be weak. It takes better than 20,000 volts to get the thrusters moving. Also, if your power cables are too close to the thruster (or too close to each other) the spindle may be hampered by the escaping high voltage corona.

When I first built my thrusters, they would turn a half revolution and stop, still hissing. This happened because I ran the + connection from the base to the top commutator inside the PVC pipe, and the bell wire was leaking enough high voltage to create a corona that 'caught' the capacitors as they passed. To fix this, I removed the bell wire from the PVC upright and made my + connection at the top of the frame, as described in the current Instructable.

You may experience arcing between the front and back thruster electrodes. This kills thrust and may have weird side effects around your house. Every time I get a high voltage DC spark, it drives a digital clock/thermometer in my upstairs bathroom crazy. To cure arcing, try sliding the cylinder electrodes a little farther away from the disk electrodes. Don't separate them too much or you'll kill the B-B effect. If that doesn't help, get a large electronic resistor in the low megaohm range and attach it to the + connection at the top of the thruster frame. Clip your + lead from the CRT to the resistor. That ought to cure most arcing problems.

Here's the NASA report on asymmetrical capacitors:

Good luck, and be safe.

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