VISHAL JOSHI: HOW TO BUILD A SIMPLE ROBOT
http://www.squidoo.com/fun-experiments-2#module32387602
Friday, December 10, 2010
HOW TO BUILD A SIMPLE ROBOT
EXPERIMENT #3 - HOW TO BUILD A SIMPLE ROBOT
thanx to this website CLICK TO SEE IT
This cardboard robot can pick up small objects with its specially designed arms.
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?
Wednesday, November 10, 2010
Super Simple Sun Tracker
Super Simple Sun Tracker
THE CREDIT MUST GO TO AUTHOR JESOPINO
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.
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!
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
Thursday, September 16, 2010
Types of Conductors and specification
Types of Conductors and specification
EE35T - Overhead Line Design and Transmission Line Construction
The fundamental purpose of a Transmission or Distribution Line is to carry the active power from one point to another.
A Transmission line should possess the following characteristics:
(ii) ACSR/AW - ACSR Conductor with Aluminum clad steel reinforced core. This is very useful in corrosive environments.
(iii) ACSR/SD - ACSR Conductor that is self damping. It is more expensive than regular ACSR, and comprises two trapezoidal layers of conductor around a steel core. The strands are made of #6201 Aluminum, and the structure makes them self damping against Aeolian Vibration. They can be strung at very high tensions.
(iv) ACAR - Aluminum Conductor Alloy Reinforced. This comprises strands of #1350 Aluminum around a core made of #6201 Aluminum. It is lighter than ACSR, but more expensive and just as strong. It is used in corrosive environments.
(v) AAC-1350 - Aluminum Conductor made of #1350 Strands. It is used in construction that requires good conductivity and short spans.
(vi) AAAC-6201 - Conductor composed of #6201 Aluminum Alloy. It is stronger than ACSR, and lighter, but more expensive. It is used for long spans in corrosive environments.
Some factors to be considered when selecting the transmission line conductors include:
Thus:
Thermal Capacity: The conductor should be able to carry the maximum long term load current without overheating. The Conductor is assumed to withstand a temperature of 75 degrees celsius without a decrease in strength. Above this temperature, the strength decreases.
Economic Considerations: The conductor is rarely sized to meet the minimum requirements. The total cost per kilometer or mile must be taken into account as too the present worth of energy losses associated with the conductor. There must also be some compensation for load growth.
2. Insulators
There are two types of insulators: Suspension Type and Pin Type. The function of the insulator is to support and anchor the insulator. Additionally, they also insulate the conductor from ground and tend to be made of either glass or porcelain and in some cases, ceramic.
3. Support Structures
These serve the purpose of keeping the conductors at a safe height from ground as well as at an adequate distance from each other. The construction of the support is dependent on the cost. The cost takes into account the design and the materials as well as transportation and labour. Galvanised steel self supporting towers as well as wooden H-frame and K-frame are commonly used. The erection of structures is an important part of transmission line construction. The method chosen is dependent on:
Structure spotting is a process that determines the height, location and type of consecutive structures on the plan profile drawing. Structure spotting should closely conform to the design criteria established for the line. The following steps should be taken when spotting structures:
1. Towers used for straight runs
2. Towers used when bends have to be made in the path of the line (Deviation Towers)
In putting down deviation towers, guyed wires and guyed blocks have to be used to balance the tensile forces on the tower. When two forces act on a tower (which is usually the tension of the line), a resultant force is produced. A guyed wire is used to counteract this resultant force so as to prevent the tower from collapsing. The guyed block is also used, and this is the buried block to which the guyed wire is connected. The block is usually buried at an angle to negate the resultant force on the line. The above description is figuratively shown below.
Figure 1. This is the diagrammatic representation of the use of the deviation tower with the Guyed Wire
Figure 2. This is the diagrammatic representation of the use of the Guyed Block
Some Basic Definitions to be familiar with
Right Of Way:
This is the legally granted free space that may be leased or purchased when constructing overhead lines. The right of way has to take into account the environmental and aesthetic value of the area through which the line passes. In locating towers and stringing the lines, the electricity commission has to determine the route of the line. Once this is established, then it is necessary to determine the right of way. In some cases, the right of way cannot be obtained, and as a result, alternate routes, in which the right of way can be obtained must be devised. Right of Way must be clear of trees, or any obstructions which may cause the line to fault, or touch, or even result in the tower collapsing.
Sag:
Sag is defined as the vertical distance between the point where the line is joined to the tower and the lowest point on the line.
Figure 3. Diagram showing the definition of sag. The sag is as a result of the tensioning of the line and must not be too low otherwise the safety clearances may not be met. Also, the sag had to be such that it caters for ice loading in the winter of temperate climates. If the sag is large, and the line becomes heavily loaded, then the sag will further increase and breach the safety clearances. Similarly, if the sag is low, then when the line contracts in the winter, a low sag will indicate a high tension, and as a result of this contraction, the line may snap. Sag is inversely proportional to the tension of the line, and is given by the formula below.
For low tensions, the sag should be high.
Clearances must also be observed when stringing a line. The normal clearances for overhead lines are shown in the table below.
Span is the horizontal distance between two towers. The Ruling Span is defined as the assumed uniform span that most closely resembles the variety of spans that are in any particula section of the line. The ruling span is used to calculate sag and clearances on the plan profile drawing, and it is necessary in structure spotting. When stringing the line, the general rule is that the spans in the line should not be more than twice the ruling span, or less than half of the ruling span. The approximate relationship for the ruling span is given by the formula below.
labels: conductors, eevishal, electrical, electrical conductors., sdmcet, types of conductors, vishal joshi
The fundamental purpose of a Transmission or Distribution Line is to carry the active power from one point to another.
A Transmission line should possess the following characteristics:
- The voltage should be kept as constant as possible over the entire length of the line.
- The line losses must be small so as to obtain a high transmission efficiency
- The Copper losses must not overheat the conductor.
- Conductors are always bare
- They are the vital link in the transmission system and distribution system
- They must be designed to meet the specified voltage level
- The conductor consideration should include the voltage level at which the power is transmitted, the maximum allowable losses on the line, the maximum thermal capacity of the line, the current carrying capacity and the tension of the line
- Factors which affect the location of the line include the climate of the country, the atmospheric conditions and vibration of the line
(ii) ACSR/AW - ACSR Conductor with Aluminum clad steel reinforced core. This is very useful in corrosive environments.
(iii) ACSR/SD - ACSR Conductor that is self damping. It is more expensive than regular ACSR, and comprises two trapezoidal layers of conductor around a steel core. The strands are made of #6201 Aluminum, and the structure makes them self damping against Aeolian Vibration. They can be strung at very high tensions.
(iv) ACAR - Aluminum Conductor Alloy Reinforced. This comprises strands of #1350 Aluminum around a core made of #6201 Aluminum. It is lighter than ACSR, but more expensive and just as strong. It is used in corrosive environments.
(v) AAC-1350 - Aluminum Conductor made of #1350 Strands. It is used in construction that requires good conductivity and short spans.
(vi) AAAC-6201 - Conductor composed of #6201 Aluminum Alloy. It is stronger than ACSR, and lighter, but more expensive. It is used for long spans in corrosive environments.
Some factors to be considered when selecting the transmission line conductors include:
- Required sag and span between conductors
- Tension on the conductors
- Whether or not the atmosphere is corrosive
- Whether or not the line is prone to vibration
- Power loss allowed on the line
- Voltage loss allowed on the line
- Climate at the line location
Thus:
Thermal Capacity: The conductor should be able to carry the maximum long term load current without overheating. The Conductor is assumed to withstand a temperature of 75 degrees celsius without a decrease in strength. Above this temperature, the strength decreases.
Economic Considerations: The conductor is rarely sized to meet the minimum requirements. The total cost per kilometer or mile must be taken into account as too the present worth of energy losses associated with the conductor. There must also be some compensation for load growth.
2. Insulators
There are two types of insulators: Suspension Type and Pin Type. The function of the insulator is to support and anchor the insulator. Additionally, they also insulate the conductor from ground and tend to be made of either glass or porcelain and in some cases, ceramic.
3. Support Structures
These serve the purpose of keeping the conductors at a safe height from ground as well as at an adequate distance from each other. The construction of the support is dependent on the cost. The cost takes into account the design and the materials as well as transportation and labour. Galvanised steel self supporting towers as well as wooden H-frame and K-frame are commonly used. The erection of structures is an important part of transmission line construction. The method chosen is dependent on:
- Terrain
- Access Roads
- Workspace
- Experience and Availability of workmen
- Allowed time for the completion of project
- What type of structures are to be erected
- What are the natural divisions
- What are the dimensions of the natural divisions
- What are the conditions of access to the right of way
- What are the conditions of access along the right of way
Structure spotting is a process that determines the height, location and type of consecutive structures on the plan profile drawing. Structure spotting should closely conform to the design criteria established for the line. The following steps should be taken when spotting structures:
- Establish the plan profile drawing on a fixed scale
- Establish the sag template on the same scale as the plan profile drawing
- Make a table showing the conductor clearances to ground as well as relative to other overhead lines
- Decide on the horizontal and vertical span limitations due to clearance and strength requirements
1. Towers used for straight runs
2. Towers used when bends have to be made in the path of the line (Deviation Towers)
In putting down deviation towers, guyed wires and guyed blocks have to be used to balance the tensile forces on the tower. When two forces act on a tower (which is usually the tension of the line), a resultant force is produced. A guyed wire is used to counteract this resultant force so as to prevent the tower from collapsing. The guyed block is also used, and this is the buried block to which the guyed wire is connected. The block is usually buried at an angle to negate the resultant force on the line. The above description is figuratively shown below.
Figure 1. This is the diagrammatic representation of the use of the deviation tower with the Guyed Wire
Figure 2. This is the diagrammatic representation of the use of the Guyed Block
Some Basic Definitions to be familiar with
Right Of Way:
This is the legally granted free space that may be leased or purchased when constructing overhead lines. The right of way has to take into account the environmental and aesthetic value of the area through which the line passes. In locating towers and stringing the lines, the electricity commission has to determine the route of the line. Once this is established, then it is necessary to determine the right of way. In some cases, the right of way cannot be obtained, and as a result, alternate routes, in which the right of way can be obtained must be devised. Right of Way must be clear of trees, or any obstructions which may cause the line to fault, or touch, or even result in the tower collapsing.
Sag:
Sag is defined as the vertical distance between the point where the line is joined to the tower and the lowest point on the line.
Figure 3. Diagram showing the definition of sag.
For low tensions, the sag should be high.
Clearances must also be observed when stringing a line. The normal clearances for overhead lines are shown in the table below.
Span is the horizontal distance between two towers. The Ruling Span is defined as the assumed uniform span that most closely resembles the variety of spans that are in any particula section of the line. The ruling span is used to calculate sag and clearances on the plan profile drawing, and it is necessary in structure spotting. When stringing the line, the general rule is that the spans in the line should not be more than twice the ruling span, or less than half of the ruling span. The approximate relationship for the ruling span is given by the formula below.
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