WORKSHOP AND CONCEPT OF SAFETYWorkshop may be defined as a room or building which provides both area and tools (or machinery) that may be required for the manufacture of goods or repair of manufactured goods.
TOOLS USED IN ELECTRONIC WORKSHOP
1. Soldering iron
2. Soldering iron stand
3. Soldering lead
4. Soldering gun
5. Project board
6. Connecting wire
7. Wire cutter
8. Measuring meter
9. Vero board
10. Screw driver
11. Lead sucker
12. Copper clad board
13. Computer system
GOODS MANUFACTUREED/REPAIRED IN WORKSHOP
5. Automatic change over
6. Static character display
7. Power inverters
8. Dynamic character displays
10. Transmitters and receivers
11. Security system
12. Reading lamp
CONCEPT OF SAFETY IN ELECTRONIC WORKSHOP
Concept of safety may be defined as ideas, principles, rules and regulations laid down to govern the use of any workshop to ensure no injuries or loss of life due to avoidable mistakes. The world had lost and continuously loosing great engineers, technologist, technicians and artisans most times due to carelessness on the side of workers. In order to avoid work place/shop accidents laid down principles and ideas are there to curtail accidents in workshops. These are called the concepts of safety in work shops
HAZARDS IN WORKSHOPHazards are situation that poses a danger or a threat to life, health, property or environment.
DIFFERENCES BETWEEN HAZARD AND ACCIDENT
ACCIDENT: This is an unexpected or unforeseen event that can result to injuries, loss of property or death. In accident, the victim is not pre-informed before it occurrence.
HAZARD: this is a situation that makes accident imminent and expected. Its possible occurrence is always known.
SOURCES OF HAZARDS IN WORKSHOPS AND ITS PREVENTION
1. FRAYED ELECTRICAL CORDS: these are electrical conductors that pose grave danger of electrocution. The hazard here is that we know that exposed live wire if touched with bare hand can lead to severe electrocution.
PREVENTION: check at interval for frayed electrical cords so that they are immediately replaced.
2. WORKSHOP NOVICE: it is very hazardous for someone who did not understand the functions and use of tools in workshop to be left alone to use the workshop and its equipment.
PREVENTION: ensure that anyone that is to use the workshop and its equipment is knowledgeable enough to do so.
3. UNGUARDED MACHINERY/TOOL: heating tools, pointed tools, cutting tools and the likes are sometimes exposed in a way that creates hazards to those working in the workshop.
PREVENTION: ensure that all machines, tools that pose threats to human health and life should be properly packed so that they would not be sources of accidents in the workshop.
4. CONSTANT LOUD NOISE, STEADY VIBRATION, EXCESS EXPOSURE TO SUNLIGHT, HEAT, COLD AND ULTRAVIOLET RAYS: all these are hazardous condition.
PREVENTION: at low and mild state proper clothing, eye glasses, ear muffs, safety boots etc should be worn but at extreme conditions robots should be used to do the work.
5. WORKING AT A HEIGHT: working with ladders and cranes takes a work some distance away from the ground surface. This is very hazardous condition.
PREVENTION: the worker is to wear effective safety belt once working at a height.
BASIC RULES AND REGULATION IN USE OF A WORKSHOP
1. On no occasion must a worker fight in the workshop.
2. Any form of play/joke is prohibited while you are in the workshop.
3. Know the correct use of a tool, machine or component before using it.
4. There must be at least 2 persons using the workshop at a time.
5. All rules specific for a particular workshop use that is provided must be followed accordingly.
WORKSHOP FIRE ACCIDENT
A workshop fire accident is defined as an undesirable and unexpected event which emits heat, smoke and/or flame, which has the potential to cause damage, may require intervention either mechanical or human.
Of all accidents in workshop, fire accident is the most damaging and as such a careful detail study of this accident is important.
MAJOR CAUSES OF FIRE
1. CARELESSNESS, negligence and human errors.
2. Electrical Wiring, Electrical Outlets and Faulty Wiring.
3. Electrical appliances.
4. Heating devices of any kind e.g. Soldering iron
5. Electric Short circuiting.
6. Playing with sources of fire in the workshop.
TYPES OF FIRE BASED ON THE CAUSE
1. CLASS A: this fire is caused by wood, candle, lighter, matches and the likes. This can be put out using ordinary water.
2. CLASS B: this fire is caused by flammable materials like gasoline (fuel, gas, diesel etc.). This fire can be put out using fire extinguisher.
3. CLASS C: this fire is cause by electrical devices or defective appliances. The fire triangle in this situation uses the electrical current in place of a lighter or match as the source of heat for the fire. Using water to extinguish this type of fire would result in electrocution, so it should never be used. To put this fire out a special protein based foam is often used, or if possible, the source of the electricity is cut off. Special fire extinguishers can be used to fight this class of fire.
4. CLASS D: these are fires that are caused by reacting metals. These metals can be magnesium, uranium, calcium, potassium, sodium, plutonium, or titanium. These types of fires are very hot, often reaching over 1200 degrees. Water should not be used to extinguish this type of fire because water actually makes the fire hotter in this case. A dry powder is often used to extinguish these fires, which smothers the oxygen supply to the fire.
5. Class K: these are fires that involve cooking oils, grease or animal fat and can be extinguished using Purple K, the typical agent found in kitchen or galley extinguishers.
FIRE FIGHTING EQUIPMENT
Fire Extinguisher: This is a cylindrical metal painted red containing chemicals such as soda and acid for putting out small fire.
1. Hold it uprightly.
2. Withdraw safety cap or pull off the safety pin.
3. Press the lever fully down.
4. Point the nozzle at the base of the fire but not at the surface of the fire.
Sand Bucket: This is an iron bucket painted red and loaded with dry sand for putting out small fire.
1. Simply sprinkle the sand to cover the fire. Do not add water. The carbon in sand will act as pressure to put off that fire.
Fire Blanket:The fire blanket is manufactured from woven fibre glass (that is yarn made from glass material). It resembles woven sac and is good for combating domestic and industrial fire outbreaks.
1. Remove blanket from the case.
2. For domestic use, gently place the blanket on the fire to choke oxygen out the blazing fire.
3. For industrial fire, wrap yourself tightly with the blanket for protection against the fire.
Fire Alarm: This is a siren made to alert the people if there is a fire out-break when the switch is booton is presses.
1. There is usually a glass seal covering the swith pad of a fire alarm device. Just break or hit the glass with something and this will trigger off the alarm immediately.
2. Do not play with this device when there is no fire outbreak. This could lead to a stampede or some form of unforeseen accident.
DESIGN AND CONSTRUCTION OF FREQUENCY BASED READING LAMPThis is a battery powered electric lamp that can conveniently give effective lightening for an establishment and our home at relatively low energy consumption. It is a lamp that works based on converting direct current to alternating current before it is used by the lightening bulbs (light emitting diodes). It has been observed that bulbs using direct current constantly drains the energy of the battery thereby limiting the duration the battery can stay. In this design, instead of using direct current that the battery gives in driving the bulbs, we would convert this direct current into alternating current before using it to drive the bulbs. Because alternating current has both ON state and OFF state, there will surely be an interval when the battery rests from steady drain. It is as a result of this resting time that the energy of the battery is saved.
The same kind of lamp that is DC driven can stay for 3 days before draining a 9V battery. But this new design using similar battery can stay 12 - 15 days depending on the frequency regulation. This light is frequency based because it blinks 50 times in one second (40Hz). With such speed, human eyes can no longer detect its blinks due to persistence of vision of the human eyes.
To really understand this project, we are going to list components used.
1. SWITCH: this is an electronic component that makes or breaks circuit that is closed. This component is very important because, it helps us to conveniently switch OFF our device when not in use and ON when we want.
2. BATTERY: this is the source of energy to our device. It is a 9V battery but we can also use any other battery within 5Volts -> 18Volts.
3. LIGHT EMITTING DIODE [LED]: this is an electric bulb that emits light at very low battery energy consumption. It is a semiconductor material.
4. RESISTOR: this is an electronic component that limits the flow of electric current. Whenever current flowing through a component is too much, that component may get damaged. To avoid damaging a component due to excess current we usually connect a resistor in series or parallel to that component. Resistors are measured in Ohms. For the purpose of this project, we will be describing two kinds of resistor.
I. FIXED RESISTOR: the value of this resistor does not change once it had been manufactured. It is also color coded and its resistance can be measured by these color bands.
II. VARIABLE RESISTOR: the value of this resistor can be varied using its tunable or adjustable knob, it is sometimes called potentiometer. It has no color band its value is directly written on it.
5. CAPACITOR: this is an electronic component that can store and discharge its stored current. It is measured in farads [F], for very small value it is measured in micro farads.
6. TRANSISTOR: this is a semiconductor device that can either be OFF or ON, that is it is an electronic switch. It is also used as amplifiers and current buffer.
7. 555 TIMER INTEGRATED CIRCUIT [IC]: this is the most complex electronic component in the design. It is an already made combination of resistors, capacitors, transistors and diodes intelligently connected to have the ability to generate alternating current at its output.
ELECTRONIC COMPONENT SYMBOLS AND IDENTIFICATION
PROJECT BOARD BASED LAMP
Reading lamp circuit
3. Light emitting diode
4. Fixed resistor
5. Variable resistor
8. 555 timer integrated circuit
CIRCUIT DIAGRAM OF FREQUENCY BASED READING LAMP
Intelligent interconnection of different electronic components gives us electronic gadgets. Circuit diagram is a paper drawing showing how different components are to be connected physically within a circuit board. The interpretation of such diagram is possible when we know the circuit symbols of the components involved.
CIRCUIT DIAGRAM OF THE FREQUENCY READING LAMP
The central component in the above design is the 555 integrated circuit. It has 8 pins. The 4th pin and the 8th pin are to be joined together. Pin 8 must be connected to the positive terminal of the battery. Pin 1 must be connected to the negative terminal of the battery. Pin 3 is the output of the Integrated circuit. Pin 2 and Pin 6 are to be joined together. The variable resistor has 3 terminals, one (1) terminal can be connected to the junction of the 4th and 8th pin of the IC or to the positive terminal of the variable resistor is to be joined together and connected to one terminal of the 4.7k resistor. The second terminal of the 4.7k resistor is to be connected to the 7th pin of the IC. The 120k resistor also has two terminals one is to be connected to pin 7 of the IC and the other terminal is to be connected to the junction of pin 2 and 6 of the IC. The 1uf capacitor also has two pins; the positive terminal is to be connected to the junction of pin 2 and 6 of the IC. The other terminal of the capacitor is to be connected to the negative terminal of the battery. The output of the IC which is pin 3 cannot handle the current drawn by the 8 light emitting diodes effectively. That is while the transistor has to come in and it is called a buffer transistor. All the 8 LEDs are to be connected in parallel. The positive terminals of the LEDs are to be connected to the positive terminal of the battery. And the negative terminals of the LEDs are to be connected to another 4.7k resistor that is to be connected to the pin 3 (output) of the IC. All terminals that are to be connected to the positive terminal of the battery must pass through the switch.
All these interconnection will be done on a project board before it will be transferred permanently to the Vero board.
PRINCIPLE BEHIND ENERGY SAVING ABILITY
Below is a graph of current drain with time of a given 9V Battery both for the conventional lamps in the market and the improved lamp we have designed.
The second graph shows our proposed design. It is obvious that steady current drain has been eliminated thereby saving the battery’s energy.
STRUCTURE OF MATTERMatter is anything that has mass and occupies space (volume). Beginning from elementary particles, composite particles, atoms, elements, molecules, compound, mixture or ions is referred to as a matter in as much as it has mass and occupies space.
ELEMENTARY PARTICLES: these are particles of anything in the universe known to have no sub-structure. That is it has not been made from any other thing. Examples of elementary particles are quarks, leptons and antiparticles they are collectively called the fermions. We also have the gauge bosons and the Higgs bosons they are collectively called the Bosons. These particles gave birth to the composite particles.
COMPOSITE PARTICLES: these particles are gotten from the combination of elementary particles. Examples are proton, neutron and electrons etc. In your study of elementary physics and chemistry proton, neutron and electron are wrongly referred to as elementary particles. The composite particles gave birth to atoms.
ATOM: an Atom is the smallest particle of any element that still retains all the characteristics of that element. Or an atom is anything that consists of only composite particles (proton, neutron, electrons etc.). Atoms consist of a positively charged central dense nucleus (proton and nucleus) that is surrounded by one or more light weight negatively charged particles called electron. Any substance that is made up of a specific atom is called element.
STRUCTURE OF MATTER: all matters are not composed of Atoms but solid, liquid and gases are composed of atoms. It is worthwhile to note that atoms are not the basics of all things because something gave birth to atoms but for your level we shall be using the structure of atoms to study the structure of matter. Our study of matter based on structure of atom is very correct since we are limiting the study to solid, liquid and gas only.
ATOMIC STRUCTURE OF COPPER
ELEMENT: this is any material that is composed of only one type of atom. An aggregate or lump of sodium atoms is called sodium element. Some textbooks defined element as a substance which cannot be split into simpler units by ordinary chemical processes. This definition is true though it does not tell us what an element is. It is true because when you split an element we have proton, electron, neutron etc. such splitting does not come easily. A composition of specific or different elements gives rise to molecules.
MOLECULES: this is a substance formed when two or more atoms are chemically combined. Or this is the smallest particle of a substance that can normally exist alone and still retain all the chemical properties of the main substance. A molecule may consist of atoms of a single chemical element, as with oxygen, Hydrogen gas or may consist of atoms of different elements, as with water. Molecules that are formed from different elements are better referred to as COMPOUND.
COMPOUND: this is a molecule whose constituent atoms are from different elements.
ION: this is an atom or group of atoms which possesses an electric charge. Nature has made all atoms to be neutral, but when chemists or environmental effect succeeds in removing an electron or adding an electron to an existing neutral atom(s) we have IONS.
MIXTURE: this is a substance whose constituent are not chemically combined together.
STATES OF MATTER Since elementary particles, composite particles and atoms are not solid, liquid or gas but they are also matter, to make the definition of matter as anything that has mass and occupies space to be correct we have currently six states of matter
5. Bose-Einstein condensate
6. Fermionic condensate
Solid, Liquid and Gaseous states are the only states that are important to us because of kinds of substances we will be dealing with in this subject and your level. It is good to note that the relationship that exists between atoms of any object will determine it will be a solid, liquid or gas.
SOLID: this is an object whose atoms are closely packed together by a strong force that makes it very rigid in shape.
LIQUID: the atoms of this substance are not closely packed because of a very weak intermolecular force that that exists among the constituent atoms. Such substance tends to flow.
GAS: there is virtually no force of attraction between atoms of this substance and they tend to fly away.
CONCEPT OF ELECTRICAL CONDUCTIONDefinition: this is the movement of electrically charged particles through a transmission medium. For electrical conduction to take place in any medium, that medium must have mobile electrons, ions or valence electrons. To determine the conductivity of a material the overall electron distribution is considered. On that note we have three types of materials.
This is a material that is very rich in mobile electrons. Atoms with few electrons in their valence shell tend to have more free electrons since these valence electrons are more loosely bound to the nucleus. In some materials like copper, the electrons are loosely held by the atoms and so does the neighboring atoms that it is difficult to determine which electron belongs to which atom. Under this condition, the valence or free electrons tend to drift randomly from one atom to another. Therefore, within a piece of conductors there is un-directional movement of electrons within it. In order to make this electrons movement directional, an external force in the form of electromotive force (battery) is usually applied.
Example of conductors is copper, silver, gold, aluminum.
INSULATORS: these are material with little or no mobile electrons that is needed for electrical conduction. It should be noted that it is not that insulators do not have electrons but the electrons are so rigidly bonded that there is no free electrons (valence) left for carrying out conductions. Examples are Rubber, Ceramics, Glass, Wood, Plastics, diamond e.t.c.
SEMICONDUCTOR: this is a material that has little mobile electrons when compared with conductors but not deficient like in insulator, thereby making it neither poor conductor nor good conductor. Looking at the structure ordinarily, tend to make people neglect it. But the unique behaviors in circuits have made it the most important invention of man and the fundamental of modern technology. Example Diodes, transistors, integrated circuit e.t.c. their ability to conduct electricity as a result of presence of electrons and holes. The true understanding of holes is beyond the scope of this lesson. Further treatment of semi-conductors will be done in second term.
CURRENT, VOLTAGE AND RESISTANCEEverything moving controllable or uncontrollably in this universe has voltage, current and resistance; though usually called different names. In other to visualize this lesson, let look at the current, voltage and resistance in human being.
THE HUMAN BLOOD
Current are stream of particles called electrons. Blood of human contains particles called hemoglobin, when the movements of these particles come to stand still the person dies. Therefore, for one to remain alive these particles must be set to motion appropriately. Intake of air(voltage) is needed else the movement of these particles will be stopped. Illness(Resistance) also resist the orderly movement of these particles. The level of resistance posed on these particles. The level of resistance posed on these particles by illness a times results to death. Therefore, blood is equivalent to current, air is equivalent to voltage and illness is equivalent to resistance. Current: this is the directional movement of electrons among atoms of given conductor. Visualize current as an ocean of electrons, such as is present in all conductors. Example, a piece of wire that is made from pure copper contains trillions of atoms of copper. Every atom of copper has one free electron available to initiate current flow. Then imagine trillions of such mobile electrons in just a tiny piece of copper. The absence of electron in a material makes that material an insulator. UNIT FOR CURRENT: the symbol for current is I. Current is measured in Amperes or Amps. An Amp is the amount of electrical current that exist when a number of electrons having one coulomb (6.25 X 1018 electrons) of charge move past a point in one second. Ammeter is the instrument for the measurement of Current.
VOLTAGE: this is the force responsible for the free flow of electrons within conductors. It is known that conductors contain trillions of particles (electrons) but these particles move in a disorderly manner. To initiate current flow, an orderly movement of these particles is required by providing a force called voltage. This force is also called electromotive force (EMF) and there are devices capable of providing such force. Eg 1. Battery 2. Generators 3. Photovoltaic cells (solar cells).
THE UNIT FOR VOLTAGE: the symbol for voltage is V. and it is measured in volts. A voltmeter is the instrument for the measurement of voltage.
RESISTANCE: this is a force that tends to restrict the rate at which electrons move in conductors. All materials in life have internal resistance. It is impossible to have a conductor without its own internal resistance. It should be noted that resistance has its advantage and disadvantages. There will be no bulbs without resistance. UNIT FOR RESISTANCE: the symbol for resistance is R. and is measured in Ohms. An Ohmmeter is the instrument for measuring resistance.
NOTE: one ohm is the amount of electrical resistance that exists in an electrical circuit when one amp of current is flowing with one volt.
THE LAW OF CHARGES
REPULSION: two electrons win tend to repel each other because both have a negative electrical charge. Two protons will also tend to repel each other because they both positive charge.
ATTRACTION: A proton and an electron will tend to attract each other because of their unlike charge.
The law of charges states that like charges repel and unlike charges attracts. The practical observations of the ongoing discussion on the law of charges are better understood using two bar magnets
This is a unique material (stone or metal) with its extremes called North pole and South Pole possessing excess protons and electrons at these poles respectively.
It has excess protons at the North Pole and excess electron at the South Pole.
Bringing two South Poles together or two North Poles together causes serious repulsion.
Bringing South Pole close to a North Pole results to immediate attraction.