HOW TO BUILD A SIMPLE ROBOT

EXPERIMENT #3 - HOW TO BUILD A SIMPLE ROBOT

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This cardboard robot can pick up small objects with its specially designed arms.

1. Seven cotton reels or plastic tubs with lids
2. A small cardboard box
3. A hook or a magnet
4. Three knitting needles
5. Modelling clay
6. Cotton thread
7. Wire
8. Thick card
9. Sticky tape
10. Scissors
11. Corrugated cardboard

12. A cork
13. Paper fasteners

CATERPILLAR WHEELS

1. Slide a cotton reel onto each knitting needle. Push the needles through the base of the box. Place cotton reels on the ends of each needle and secure the ends with a lump of modelling clay.

2. To make a caterpillar track, cut two strips of corrugated cardboard. They should be long enough to wind over all three sets of wheels. Use sticky tape to join the ends of the track together.

AN ARM THAT STRETCHES

1. Cut six short strips from a thick sheet of card. The strips should be 18 centimetres long and 2 centimetres wide.

2. Lay the pieces of card out in a criss-cross pattern and join them together with paper fasteners. Use a large paper fastener to attach the arm at point "A" to the side of robot's body.

A PULLEY FOR LIFTING

1. Cut a hole in the back of the box, big enough to fit a cotton reel. Wind thread round a cotton reel, and tie a hook on the end.

2. Push the wire through one side of the box. Thread the cotton reel onto the wire. Push the wire out the other side.

3. Bend the wire to make a handle.

4. Push some wire through the cork. Bend the wire at either side to make 'legs', as shown. Push the legs through the front top of the box.

5. Pull the cotton over the cork, with the hook hanging down.

EXPERIMENTS WITH YOUR ROBOT

Collect as many objects as you can. How many of these objects can you pick up with your robot? What can you pick up with the pulley and hook? What can you pick up with the stretching arm? What would happen if you used a magnet instead of a hook?

Super Simple Sun Tracker

Super Simple Sun Tracker

Enhanced By vishal joshi at 10:27 PM

THE CREDIT MUST GO TO AUTHOR JESOPINO

CLICK HERE FOR SIMPLE SOLAR TRACKER HOME MADE VIDEO

ವಿಶಾಲ ಜೋಷಿ

Without using complex circuits and sensors, It was able to make simple home-made Sun Tracker. This one only needs Solar cells, a motor and some gears, hope it works.

I Got some solar cells since two months ago, but it wasn't until the last week I decided to put those solar cells to work. I really didn't have any good idea for it, I was thinking to use it to power toys or some homemade projects. Finally, I thought I can use those solar cells to charge rechargeable batteries.

Bad idea. Rechargeable batteries needs from 8 to 14 hours to get fully charged but using the solar cells in a fixed position, it only gets about 6 or 7 hours of direct sunlight. The solution: A sun tracker.

  A sun tracker allows to get 9 to 12 hours of direct sunlight, enough to charge some batteries. I saw some sun tracker circuits long time ago but those are kinda complicated; sensors, fotoresistors, digital circuits, transistors, etc. As I just need something simple, I decided to build my own.

Here is how it works:
The sun appears every morning from the east. (Miracle!)
The sun dissapears every evening from the west.
So... the sun tracker should move from east to west, go back to east and move to west, again and again. That's all!

  Here are the parts needed:

A motor.

Some gears.

A small solar cell.

A big solar cell.

Some pieces to build a base.

Aluminium foil, tape or glue and cardboard. (Not showed)

  I did use some LEGO block and gears because it was handy. Any other pieces like meccano, knex or any other construction set works fine. This is only to give you an idea how I built my own.
There are two parts, the main base and the... the.. the other one that rotates. Call it whatever you want to call it.

  The main gear is fixed to the base. It doesn't move.
The axle is also fixed to the gear. It provides support to... hmmm... to... that thing that rotates. Let's call it "the rotator".

  This is my design of the mechanism. The speed of the rotation is reduced by the gears and slows the movement. We don't want the solar cell to fly away when the sun tracker rotates at 5,000RPM, right?

  Now it's time to install the solar cells. The small one provides power to the motor. It is connected directly to the motor. No sensors, No transistors, no fancy circuits.
There is an aluminium foil covering one side and the top of the small solar cell (just 1 inch by 5/8"). It is installed almost vertically. I will explain the reason of it later.

  The Main solar cell is the bigger one. I did install it in a 40 degree angle just as example. I think ideal angle is 60 degrees. Under that solar cell the rechargeable batteries will be installed (not showed in the photo). I guess is not a good idea to expose the batteries directly to the sunligh.

  This is my sun tracker working. The sunlight was so bright that, actually, the motor was working without stop. As you can see on the photo, I did put a cardboard to cover the small solar cell and "calibrate" the light on the circuit.
Here is how it works:
The small cell provides power to the motor directly. If there is no sun, or night, the motor is not going to work. The cardboard covers the cell to ensure the motor will turn on ONLY when there is enough light to move the sun tracker.
The foil covers the top and the left side of the small cell to provide shadow to it. When the small cell is on the shadow, the Main solar cell is getting direct sunlight. Those solar cells are installed in a 90 degrees direction.
If the sun moves to the west, the small cell gets light and powers the motor until the aluminium foil's shadow turns it off. In the evening, When the sun hides, the sun tracker will not move, the main solar cell will be facing west, the small solar cell will be facing north.
The next morning, the sun will rise from the east side. The sunlight will be reflected by the aluminium foil to the small cell, so the sun tracker will turn to the other side; east. This cycle repeats again and again.
Let's say, there is a big cloud and there is no sun for some hours, What is going to happen? When the sunlight comes back, it will be directly to the small solar cell, so it will locate immediately the position of the sun.
What if there is no sunlight all day long? It doesn't matter. The aluminium foil and the alignment of the solar cells allows to turn it on even if the sun comes from the back of the solar tracker.
What if there is a tornado? Forget about the sun tracker! RUN! GET COVER!
What if I don't want to the sun tracker to rotate?

vishal joshi'S

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