Introduction: CARDBOARD SOLAR LAMP
I made this cardboard solar lamp for reusing the waste cardboard dumped in my dustbin.Through this instructables I try to aware people about the merit of reusing papers/cardboard and adverse effects of cutting tree.
Features of my lamp :
1. Solar charging : I choose this option to save energy and to protect our environment.
2 Charging through dc adapter : when there is cloudy weather lamp can be charged by adapter.
3.Use of dc boost converter : The power bank which I used have inbuilt boost converter
which can extract maximum juice from the battery.
4. Led indication : During Charging (RED) and load plug in (Blue)
5. Uses : Bedroom light,reading light,searching light,as a candle
6. Safe for child : No chance of any electric shock (operate at only 5 V)
7.Light Weight : Easy to carry
Awareness of save trees :
Importance of Trees :
Trees provides us with two of life's essentials, food and oxygen. As we evolved, they provided additional necessities such as shelter, medicine, and tools.Trees increase our quality of life by bringing natural elements . Trees contribute to their environment by providing oxygen, improving air quality, conserving water, preserving soil, and supporting wildlife.
Benefits of Recycle cardboard/papers :
1. It reduces the negative impact of landfills on our environment.
2. Recycling saves natural resources like plants,minerals and water
3. Recycling saves energy.
4. Recycling can reduce water and air pollution.
5. Recycling reduces waste disposal costs.
6..Recycling paper saves trees, water and the energy needed to cut down, transport the trees, and grind them into paper pulp.
Step 1: Tools and Materials Required :
1. Waste Cardboard
2.Wax paper (trace paper)
3. Color paper (black)
4. Aluminium Foil ( Amazon )
5.Scotch magic tape and mounting squares ( Amazon )
Electronics parts :
1.Power Bank ( Amazon )
2. 4nos of 1 Watt Power LEDS ( Amazon )
4.Diodes - IN4007 ( Amazon )
5. Voltage Regulator -7805 ( Amazon )
6.Capacitors (100muF and 10muF) - Amazon
7. Dc jack ( Amazon )
8 . Switch ( Amazon )
9. Spare USB cable
10. Mini Solar panel (2W ,6V) - Amazon
1.Glue Gun ( Amazon )
2.Hobby Knife ( Amazon )
3. Soldering Iron ( Amazon )
4.Screw Driver ( Amazon )
5. Wire Stripper /Leatherman ( Amazon )
6. Ruler ( Amazon )
7.Pencil ( Amazon )
Before making the lamp first look the complete form. So that you can visualize what shape of cardboard exactly you need during the cutting.
I will recommend to use a cutting mat for cutting of cardboard which prevents damage of your tools and scratches in the floor or table.
I divide the the entire structure of cardboard lamp into few small structures.Make the small structures first then assemble it.
1. Base of the Lamp
2. Side Window
4. LED Tower
Step 3: Base of the Lamp
The Base of the lamp consists of base, side walls and Roof ( not the roof of lamp)
Before Cutting the board, first make the shape by using scale and pencil.
Mark a square of size 15 cm x 15 cm by pencil
Cut the shape by using Hobby Knife or paper cutter.
First cut with a light pressure just above the pencil mark and then put sufficient pressure on knife to cut perfectly.
Cut 3 numbers of similar shape.
Attach two squares one above the other.Hard glue it .I add two similar shape to make the base thicker which provide
strength to the structure as well increase the weight.If the weight is very small then there may be chance of topple the lamp.
Side Walls :
Mark a rectangle of size 15 cm x 3 cm over the cardboard
Cut the shape by using similar tricks as before.
You used two square shape for base the remaining one is used for making the roof.
Make a circular hole of around 3 cm diameter.
Place the side walls above the thick base.Glue perfectly for sufficient strength.
Note : In this stage don't glue the base roof.It will be attached later.
Refer the above picture for clear understanding.
Step 4: Side Window :
The side window is made of two parts
Mark 4 rectangles of size 15 cm x 12 cm
Mark a concentric rectangle of size 11 cm x 8 cm
Cut the outer rectangle first then cut and remove the center portion (Inner rectangle) of the above shape.
Here actual glass is not used.First I thought to use OHP sheet to make this.
But as High Power LEDs are very bright and difficult to see directly.It is also very harmful to naked eye.
So finally I decided to use Wax paper ( tracing paper) which is not transparent as like OHP sheet.
It also diffuse the light which make the lighting effect more attractive.
Cut the 4 rectangles (Wax paper) of size 13 cm x 10cm
First I stick the glass on the frame by using glue.when the glue dried I found that the wax paper squeezed all around.
It looks very ugly.So later I removed the wax paper carefully and stick the fresh one by using Scotch magic tape which gives a brilliant result.
Step 5: LED Tower
The Led tower is used for mounting 4 high power led (1 Watt each)
Cut 4 rectangles of size 8 cm x 4 cm
Cut 4 aluminium foils of same size
Paste the foil above the cardboard.
The aluminium foil serves two purposes one as a reflecting medium and other for heat dissipation.
Mark two dot marks just two sides of led heat sink and make the holes by using a sharp object or a screw driver.
Cut 4 numbers of red and black wires of length 6 to 7 cm and 2 wires (red and black) of length 15 cm.
My led have already heat sink attached if you don't have then first attach heat sink.
Solder red and black wires (short length) with positive and negative terminal of LED respectively.
Insert the red and black wires from led into the hole made earlier.
Make the tower by joining all 4 rectangles (use glue gun)
Join all the 4 red wires and black wires into two junction.(parallel connection of LEDs) Now solder the red wire junction with the long red wire and black wire junction with the long black wire. Use insulating tap to cover the bare parts of conductor to avoid any short circuit. These two wires are finally goes to battery (power bank). At this stage check the working of led by connecting the terminals with any battery bellow 4.5V.
The details of schematic will be discussed later .
Make it at your own risk
The high power led used in this project produces heat which may burn the cardboard and there may be chances of catching fire. So I request to use proper heat sink instead of aluminium foil which is not sufficient for dissipating heat.During making this lamp I forgot this safety point.One of the community member ( nqtronix) reminded me this point.
Alternative Solution :
You may also use Super Bright LED ( flat top ) instead of high power led which doesn't produce much heat ,no risk of fire and it consume less power also. See the picture for new led tower which uses 30 super bright LED . I bought it from nearest store but it can easily make by using the same cardboard tower.I tested 20 LEDs is more than sufficient to produce same illumination.
Mount 5 LEDs in each sides of the tower in vertical fashion.
Connect all the super bright led in parallel.
The leds shown in the pictures are 8mm ,3.5V,30mA. But small size bright led also works good.
Step 6: Top Roof
The top roof is very similar to a pyramid structure.It consists of 4 triangles
Cut 4 similar triangles of size 12 cm (sides ) and 14 cm (base).
First join all the top vertex of triangles and hold it by using glued tap.
Take helps from any family member or friend to make this structure.
Glue all the triangles to make the pyramid.
First I tried to attach the triangles above the side window but found so much difficulty.Later I make it on the ground
and placed over the side window.
Step 7: Assemble All the Parts Made Earlier :
Place the led tower above the base .Pull the red and black wires through the center holes of the base.
Place all the side window one by one on the four sides.I leave around 1 cm space from the edge.
Place the Pyramid structure above the side window.
The power bank I used have led indication for charging and load plug in.
I make a pencil mark above the indicator led.Then placed the power bank to any side wall of base.
Make small holes coincide with the pencil mark.The use magic tap over the holes towards inner side.
Two place the power bank firmly I used scotch mounting pad.You can use your own method.
Make two holes on any side of the base wall to mount the dc jack and switch.
After placing the switch and dc jack hard glue on the surrounding.
Paste black paper strips over all the joints by using scotch magic tape or glue.It gives attractive looks as well as prevent any leakage of light through the joints.
Step 8: Working and Making of Circuit :
How the Lamp Works :
Power from the solar panel or dc adapter come through the dc jack.
Capacitor C1 and C2 are used for filtering any unwanted voltage spikes.
Power from the solar panel or adapter may more than 5V .But the power bank accept 5V dc.
So a voltage regulator (LM7805) is used which gives constant 5V output irrespective of input voltage.
Power bank has output of 5V and 1A. But the high power LED operate at around 3.8v .So I used a diode to drop the voltage from 5V to around 4.2V. You can also use a resistor instead of diode.At this voltage LED can safely operate.
A diode D2 is used in solar panel output to prevent reverse power flow during night.
Make the circuit :
Cut the usb cable into two parts (one USB port and other microUSB port)
The USB port is used for power bank output and micoUSB port is for input.
Usb cable has 4 wires (red,black,white and green) Red is 5V and black is GND. Green and white wires are used for data transfer.As we need only power so red and black are useful for us.Trim out the unwanted green and white wire.
Connect everything as per schematics.Follow the above pics for better understanding.
POWER CALCULATION :
Battery and LED :
In my lamp 4 LED of 1W are used.
So total power consumed =4x1=4W
The power bank has a Li Ion battery of capacity 2600mAH and 3.7V
So Power bank capacity = 2600mAH x 3.7V =2.6AH x3.7 = 9.62 Watt Hour
When the power bank fully charged it can give 9.62WH.
By using this battery the lamp can run for 9.62/4 =2.405 Hour
So approximately the lamp can run for 2 hours.
Solar Panel :
The solar panel rating is 3Watt.
But remember solar panel will produce 3W at optimum sunlight.As the sunlight is not uniform throughout the day we can assume it will give 80% of rated power.
So power output from the solar panel = 3x0.8 =2.4 Watt
Battery capacity is 9.2Watt Hours
Time required to charge the battery = 9.2/2.4 =3.83 hours (approximately 4 hours)
So it is clear that solar panel can charge the battery fully in a single day sunlight.
Thanks for reading my instructables
If you found any mistakes please comments it.
Suggestions and area of improvements are always welcome.comments it.
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Can a 10mF 35V be used?