Pictorial Drawing
AN ELECTRON PUMP
September 2004
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Schematic Drawing
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Direct current (DC) generators and alternating current (AC) generators may be thought of as electron pumps. When a magnet moves past a coil of wire an electric current is pumped. Moving the magnet back and forth will pump alternating current.
(The alternator of an automobile produces AC. Inside the alternator diodes change the AC to
DC that is used to charge the automobile battery.)
A diode lets electric current move in only one direction. Diodes can change alternating current (AC) to direct current (DC). One diode can change only one half of AC electricity to DC electricity. Four diodes may be used to make a bridge rectifier that will change all of the AC electricity to DC electricity.
Diodes come in many sizes and shapes. Most are small cylinder shape and have a band painted around one end. The symbol and picture for a diode is:
Positive charges (sometimes called "holes") move in the direction of the arrow.
(The negative charges, electrons, move in the other direction.) Pay close attention to the direction of a diode.
Some bridge rectifiers are pre-wired. The symbol and picture of a bridge rectifier is:
There are special diodes that produce light. Such a diode is called a light emitting diode , or simply LED . Some LEDs make colored light and some make a white light. The positive (+) wire of an LED will be a longer wire than the negative (-) wire of the LED.
The symbol and picture for an LED is:
A capacitor (sometimes called a condenser) will hold an electric charge. It acts like a rechargeable battery. It can hold only a small amount of charge. It must be recharged every few moments or minutes. An electrolytic capacitor has a positive (+) terminal and
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a negative (-) terminal. The negative (-) terminal will be marked on the side with:
.
The symbol and picture for an electrolytic capacitor is:
SEE THE PICTORIAL DRAWING
1 - COIL -- Remove about 1/8-inch of insulation from the end of each of the two AC wires.
Each wire should be about 8" long. Solder the AC wires to the coil. (See drawing)
2 - NEODYMIUM MAGNET WARNING AND INSTALLATION – DO NOT place the magnet near pacemakers, computer disks, recording tapes, mechanical watches or color TV picture tubes! Neodymium magnets are very strong, but are very easy to break ! DO NOT let the magnet contact any iron object. The magnet can slip out of your hand and jump to an iron object and chip the magnet! These neodymium, rare earth, magnets are like glass. They are not iron!
Place the magnet inside the plastic pipe and plug each end of the pipe with sponge rubber. Place the plastic cap on the bottom of the pipe. Place the center piece of sponge rubber just past the 1/4-inch hole found in the plastic pipe. (See drawing) With the plastic pipe held vertical, apply one or two drops of super glue on top of the sponge rubber through the hole in the pipe. Let the glue work down into the sponge rubber and around the inside of the pipe. Keep the pipe vertical and set it aside for the glue to dry. Later, add more glue if needed.
3 - BRIDGE RECTIFIER -- Locate the PC board with the copper foil side down. For a prewired bridge rectifier, insert the wires of the bridge rectifier with the positive (+) wire aligned through terminal hole marked as number 1 in the pictorial drawing. (You may wish to write the numbers on the board.) Terminal number 1 will be the positive copper foil. Terminal number 3 will be the negative copper foil. Terminals 2 and 4 are the two AC terminals. Bend the wires to hold the bridge rectifier in place. Cut and solder the wires to the copper foil.
NEED A THIRD HAND?
Have someone help hold the circuit board for you or use a large pair of pliers with a rubber band around the handles to act as a clamp to hold the circuit board.
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4 - LED -- Insert the long positive (+) wire of the LED in terminal #5 and the short negative (-) wire in terminal #6 of the PC board. Bend, cut and solder these wires to the copper foil.
5 - COIL INSTALL -- Slide the coil of wire over the pipe with the solder terminals and AC wires facing the 1/4 inch hole. Slip the ends of the two AC wires through the 1/4-inch hole and through the pipe. Locate the center of the coil of wire halfway between the sponge rubber plugs. (See pictorial drawing.) Use a small amount of Scotch tape to temporally hold the coil in place. More tape will be added latter.
6 - AC WIRES -- Insert, bend and solder one of the AC wires to terminal #9 and the other AC wire to terminal #10. shake.
7 - TEST LED -- Shake (not too hard) the flashlight. The LED light should blink with each
8 ELECTROLYTIC CAPACITOR -- Insert the positive (+) wire of the capacitor in terminal
#8 and the negative (-) wire in terminal #9. Bend, cut and solder the wires to the copper foil.
9 - ASSEMBLY AND TEST -- Insert the capacitor and circuit board into the pipe. Pull the wires back through the 1/4-inch hole. Wrap the excess wire around the pipe. Shake the alternator. The
LED light should stop flashing and stay on for a longer period of time as the capacitor becomes charged.
10 - TAPE -- Wrap self-fusing tape over the coil of wire and AC wires from the plastic cap to just past the 1/4-inch hole. Pull the tape tight.
Wayne I. Newhart September 2004
TO EXHIBIT YOUR PROJECT:
Attach the "What I have learned" page to the Magnetic Powered Flashlight. You may exhibit the flashlight on a board (paper, plastic or wood) measuring no larger than 8-1/2" by 11". Place the flashlight flat on the board. The flashlight needs to be removable from the board for judging.
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Label each part in the drawing and explain something about each part.
Magnet ____________________________________________________________________
Coil of wire ________________________________________________________________
Diode _____________________________________________________________________
Bridge Rectifier_____________________________________________________________
Capacitor __________________________________________________________________
Light Emitting Diode ________________________________________________________
What did you find most interesting or fun about this project? _____________________
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What did you find most difficult? ______________________________________________
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You may add more on what you have learned or done on the backside of this page.
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