Introduction: Human-Powered Light--from My Book, "Doable Renewables"
This project takes human activity (winding a hand-cranked generator) and stores the energy in a futuristic way (ultracapacitors) to power a very efficient LED light. The human-powered generator is costly--perhaps your school can purchase one for the science lab.
Materials and Tools
Acrylic sheet, 12 x 12 inches, 1/2 inch thick (www.estreetplastics.com, Part # 1005001212)
Acrylic sheet, 12 x 12 inches, 1/4 inch thick (www.estreetplastics.com, Part # 1002050100)
4 solid acrylic rods, 1 1/2 inch diameter, 2 inches long (www.estreetplastics.com, Part # 5007524100)
6 medium screws
On/off switch (www.jameco.com, Part # 22200)
Voltmeter (www.jameco.com, Part # 2095040)
Human-powered generator (www.windstreampower.com Part # 454213)
13 screws, 1/8 inch diameter, 3/8 inch long
12 ultracapacitors (www.tecategroup.com Part # BCAP0350-E250)
Wire (#22 stranded)
Fuseholder (www.jameco.com, Part # 108792)
Acrylic tube, 1 inch outer diameter, 12 inches long (www.estreetplastics.com,
Part # 6013012100)
Halogen desk lamp (www.walmart.com, Grandrick 20-watt Halogen Desk Lamp)
2 wire connectors (www.jameco.com, Part # 302666)
LED light (http://store.earthled.com/products/earthled-directled-hl)
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Step 1: Step 1
Start by attaching four 2 inch long (1 1/2 inch diameter) rods to the 12 inch square, 1/2 inch thick acrylic sheet. Predrill holes in the base and the rods, but first practice using a piece of scrap wood. �Find a hole size that will just allow a medium-sized screw to slide in and out, then reduce that diameter by 1/16 inch. �If the predrilled holes are too small, the acrylic will crack when the screws are added. �Attach the base to the rods by inserting screws into the predrilled holes.
Drill holes in the upper plate, a 12 inch square, 1/4 inch thick acrylic sheet, as shown on the template below.
Insert the on/off switch and secure it with the mounting nut as shown.
Insert the voltmeter and secure it with its nut. Do not overtighten, as this can damage the meter.
Drill a 7/64 inch hole in the lower base, 1/4 inch from the edge and centered 6 inches from either end. Secure the generator cable to the base with a cable clamp fastened with a 3/8 inch long by 1/8 inch diameter metal screw.
Using a screw (and a drilled pilot hole) fasten one of the ultracapacitors to the base, on the left side. The ultracapacitor has its own mounting bracket. Placement of the ultracapacitors is primarily a function of personal taste. I suggest placing the twelve ultracapacitors on the lower acrylic base (six on the left and six on the right) and--when you are satisfied with the look--lightly mark the proposed locations using a Sharpie pen.
Attach five more ultracapacitors to the base. Drill a 7/64 inch hole in the lower base at each capacitor location. Using a 3/8 inch long by 1/8 inch diameter metal screw, insert the screw throught the mounting tab on the ultracapacitor. As you mount each ultracapacitor, connect a wire from the top (positive) of each capacitor to the bottom (negative) of the next capacitor.
Fasten six more ultracapacitors to the right side of the base. Again, connect positive on each of these capacitors to negative on the next capacitor in the series.
Attach the two final wires from the negative terminals (one on the left group, rear; one on the right group, rear) to the black wire from the generator cable. Fasten this combination to the lower base.
Attach a wire to the unused positive terminal on the left group and connect it to the unused positive terminal on the right group. Attach one end of a fuseholder to this terminal also. Attach the other end of the fuseholder to the positive wire (white) from the generator. Fasten this attachment point to the base with a screw.
Drill a 3/8 inch diameter hole in a 12 inch long piece of 1 inch acrylic tubing, 1/2 inch from the end.
Obtain a halogen desk lamp and locate the screws that secure the protective glass shield.
Remove these screws.
Remove the halogen lamp.
Return the screws to their holes. These screws hold the reflector in place.
Remove the bottom base cover from the desk lamp.
Cut wires and remove parts, leaving as much of the white wire (coming from the lamp head) as possible.
Grip the lamp neck with a set of pliers and twist the metal neck until it separates from the plastic base.
Carefully drill a 1/8 inch hole in each side of the lamp's neck--do not damage the insulation on the wires.
Pull the wires through the side holes. This is done so that the tubing will fit flush against the base and not crush the wires.
Insert the lamp's neck into the acrylic tube. The wires should be near the side.
Insert the acrylic tube assembly through the large hole in the upper acrylic plate.
Pull the wires from the lamp's neck through the side hole in the acrylic tube.
Take one wire from the lamp and crimp it into a connector with the black voltmeter lead. Attach this connector to the negative generator wire (left terminal on the base).
Take one wire from the on/off switch and crimp it into a connector with the red lead from the voltmeter. Attach this connector to the positive generator wire (right terminal on the base).
Take the other wire from the switch and connect it to the remaining lamp wire using a wire nut.
Insert the LED lamp into the lamp's head. The LED light pins are compatible with the halogen lamp pins.
Connect the generator cable to the generator.
Crank the generator until you have 14 volts, as shown on your voltmeter. Do not exceed 14.5 volts. The ultracapacitors are rated for 15 volts, but they are the most costly component in this project, so it's best not to push the limit. Turn the switch on and you should have light. The light will stay on until you reach about 9 volts, about one hour.
More to Think About
Is it practical to use a human-powered generator to run an air conditioner?
How could you use a human-powered generator to limit someone's TV time?
How much power can an average human produce?
How long would you be willing to wind a crank or sit on a bicycle and pedal?