Few years ago I read an article on lighting in developing countries, it told that 1.6 billion people have no access to electricity and a reliable source of lighting is a BIG problem for them. One Canadian company manufactures and distributes lighting kits which include a white LED array, rechargeable batteries and a solar panel. In the article there was a picture taken somewhere in Sri Lanka: the children holding these kits in their hands.
Having read the article, my first thought was what a hands-on solution to the burning problem it is. But my second thought was a bit different. Sri Lanka lies in tropical zone, so there must be rainy seasons over there. What will the folks do when it pours outside? I decided to make a weatherproof LED lamp. It can harvest both solar AND wind energy. In emergency (when the battery is dead), you can hook up the dc motor directly to the lamp and run it by spinning the motor by hand.
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Step 1: Motivation
Motivation. I was motivated to do this project by the fact that I like reading in bed and my wife is a VERY early riser. I hate disturbing her. The LED lamp turned out to be a practical and cheap solution. The lamp is green due to the two facts. Firstly, the scavenged parts, plastic bottles and scrap plywood (read trash) are used to build it. Secondly, the lamp operates with 1AA rechargeable battery (NiMh) which can be charged with a small solar panel (not shown in the pictures), by hand AND being slightly modified with a small vawt.
Being an educator, I fully recognize the importance of encouraging students to learn more about renewable energy. Thus, the lamp can be a nice scientific project for school students.
The LED lamp is multipurpose because it has 3 operational modes. When the flashing LED is inserted the way shown in the schematic, all the LEDs are on and you have a reading lamp. When the flashing LED is inserted backwards, only one LED (in series with the flashing one) is on, and you have a flashlight (VERY bright). If you remove the flashing LED, 2 LEDs (in series) are on, and you have a night lamp. I think it makes the project attractive for diy hobbyists and experimenters (mechanics, optics, electronics). It can be easily scaled up and modified by replacing the dc motor with a larger one(more powerful) and by adding another battery (see also Feel free to do experiments).
Step 2: Materials and Tools
Materials and Tools. You need the following materials:
1. 8mm plywood (scrap)
2. a strap of sheet metal (from a Coke can).
3. 5 plastic juice bottles (those with wide openings) with caps.
4. 1 5L water dispenser bottle with a cap (to build a vawt)
5. 1 plastic lid from a large Nescafe can
6. 2 BiC type pens (used)
7. 40 cm length of elastic cord (1.5 mm in diameter)
8. 1 DC motor with permanent magnets ( mine was scavenged from an old cassette recorder)
9. 1 pulley with an axe(spike) in the center (from the same recorder)
10. 1 metallic lid from a glass canning jar
11. 11 small wood screws with washers
12. 25 cm length of double core copper wire
13. 4 lengths of insulated copper wires of different colors
14. 1 AA battery holder
15. 6 press buttons made of white metal(I use them as clammers because they are cheap and well-soldered.)
16. glue (silicone)
18. Electronic parts: 1 1V5 buzzer with an in-built generator; 1 inductor (see the schematic), 3 white LEDs (10mm, 20cd), 1 flashing LED(5mm, red), 1 large capacitor(mine is 6800 mF/10V) optional, 1 Schotky diode (1N5819), 1 IC socket (dip14)
Tools: hacksaw, electric drill with drill bits, screwdriver, soldering iron, hot wire cutter, craft knife, cutting pliers, sand paper.
Step 3: Make the Base Board
Make the base board. I was lucky enough to pick up the discarded drawer at the dumpster. I sawed off the piece (8x4x5 inches). If you have plywood planks you should find the way to join them at right angle (L-shape). Cut out a strap of aluminum (I used a Coke can).WARNING: edges are VERY sharp. BE careful. Its dimensions depend on your dc motors size. Fix the motor with this strap and 4 wood screws (2 on each side). Screw on 2 juice bottle caps in the places where the lamp and the pulleys support are supposed to be installed. You need 4 wood screws to fix the cap for the pulleys support (in square arrangement) and 1 screw for the lamp(right in the center) dont screw it on tightly to be able to turn your lamp. Using 2 screws fix the battery holder on the board.
Step 4: Make the Lamp Enclosure and Pulley's Support
Make the lamp enclosure and pulleys support. Take 5 juice bottles and cut off necks (right under the collars).I did it with the hot wire cutter. WARNING: while cutting plastics dont inhale vapors they are hazardous. Glue two necks together and you will have the lamp enclosure. With the hot wire cutter make holes for power wires and double core wire (goes to the LED array). To make the pulleys support you need 3 necks and 2 caps. Drill holes in the center of the caps (8mm). Take 2 used BiC type pens and cut off 2 bits with conical metallic parts. I did it with the hot wire cutter. Insert these bits into the drilled holes. The pulleys axe(spike) will go through them. Screw the caps on the necks. Glue 2 necks together. Glue the third neck on the top and you will have the pulleys support.
Step 5: Tinkering With the Pulley
Tinkering with the pulley. You should do a lot of gluing. Glue a bit of the pen(4cm long) inside the water bottle cap(across the center to have a finger grip). Now glue this cap in the center of a metallic lid from a canning jar(on the inner side). Take a plastic lid from a large Nescafe can and cut out a ring then glue this ring on the other side of the metallic lid. To make a belt, take a length of elastic cord and tie the ends in a simple knot. Assemble and test the construction.
Schematic and circuitry. As the schematic doesnt involve any chips or transistors you neednt a pcb. Cut out a small round piece of plastic, prick tiny holes and insert leadouts then solder them according to the schematic. Before soldering the buzzer, you have to tinker a little with it. With a hot wire cutter cut off the plastic lid and then remove the membrane if you dont want to have buzzing when your lamp is on. Solder press buttons (as clammers) to the wires which go from the motor and the battery holder. Be sure they match. Solder a couple of press buttons(male and female) to power wires going from the lamp circuitry. Place the circuitry into the lamp enclosure, then put the power wires and the double core wire through the holes and solder them.
Make the LED array. Cut an IC socket into halves (7 pins in each). Make two rows of tiny holes into a juice bottle cap. Insert the halves and solder them on the other side according to the schematic using short lengths of wire. Glue a juice bottle neck on the side where the soldering was done. Drill a hole into the center of a juice bottle cap so that the double core wire can go through it. Solder the double core wire to the proper pins and screw on the cap.
You are done. Insert white LEDs and a flashing led. Place a battery into the battery holder. Connect the wires. Try to change operational modes by repositioning the flashing led. If everything works fine, disconnect the battery and hook up the motor directly to the lamp. Make the lamp work by spinning the motor by hand. You may try to charge the battery by adding a diode to the positive terminal of the battery holder.
Feel free to do experiments. There is a vast field for experimentation in this project. By adding a diode and a large capacitor you can run a small FM radio. You may opt to replace white LEDs with color ones and get a RGB lamp. Add another flashing LED and you will get a LED flasher. If you remove the LEDs and hook up a diode bridge, you will be able to run a small gadget which draws low current (few mA). Your are welcome to give your suggestions.