COMPUTER AND ELECTRICAL CONNECTIONS....

     

     Have you ever experience electrical shocks when you touch your computer , refrigerator, washing machine when they are in use ? Or Have you ever experience power cut while its not from the supply company (i.e. there is electricity in your surrounding exept your house or room ? Let us now discuss over these facts along with some information on electrical connections in our houses.

     The electric supply companies delivers AC (220 Volt, 50 Hz) through supply lines (wires mainly of Aluminium). These lines are called Phase or Live wires. there is also a neutral wire which completes every household circuit.

MAIN SWITCH or FUSE

   

     The LIVE and NEUTRAL wires are first connected to the Main Switch. Then the Live wire is fed to a Meter which measures electrical energy consumption. Fuse are connected for security. A Fuse wire is an Alloy of Tin and Lead (75% Sn + 25% Pb). It has Higher resistivity but lower melting point. Thus if for any reason current of the supply line increases, it melts and disconnect the household circuit from the main line.

 DISTRIBUTION BOARD

        Live wire from the main switch is connected to the distribution board through another fuse. From fuse the wire is fed to different switches for different appliances. There are switches, three pin plugs, indicators in a board. The live wire is first connected to the switch for the three pin plug , then from switch the wire is connected to the thee pin plug's one side ;from there to all other switches. The neutral wire starts from the appliances and ends at the three pin plug's second side and from there the wire goes to the neutral wire of the distribution line.

SWITCH

       A switch is a circuit component that can make a circuit open or close with a stroke. It is such configured, that by the help of a spring and a lever it can connect or disconnect two points. One of those point is connected to the Live wire and the other is connected to the appliance. If by stroke we make the Switch 'on' then current flows up to the appliance. The second end of the appliance is connected to the Neutral wire of the supply line.

 THREE PIN PLUG

       There are some electrical appliances such as Computers, Refrigerators, Washing machines, are used temporarily.These are connected to the supply line through Three Pin Plug. There are three wires in a three pin plug. One is Live , the second is neutral and the third is Earth .These wires are of different colours The Live wire is Red or Brown. The Neutral wire is Blue or Black. The Earth wire is Green. The color code is maintained during wiring so that any one can recognize the wires later.

EARTHING
       The Earthing is done by metallic rod and broad gauge wire . At first we dig a little. the wire is connected to the rod and the rod is buried in the pit.then  we pour plenty of salt and charcoal there. This wire is connected to the electrical switch board . the earth wire of three pin plug is connected to this wire.

        During use electrons gather on the  outer metallic surface of some household appliance. Heavy gathering may damage the appliance. These electrons are carried to earth by this Earth wire. If Earthing is not good enough then you may experience a shock when you touch the electrical appliance.

CONNECTION OF A PC
         
          If you want to use a PC at your home then at first make a good electrical wiring with very good earthing. If you are using UPS( un-interepted power supply- i.e. if there is a load shedding it can feed back power for almost 30 to 40 minutes) then connect its three pin plug to the three pin socket of the switch board.There are three Three Pin Sockets at the back of the UPS. Here we connect monitor, cpu and music system power chords. 

SWITCHING ON A PC

Firstly switch on the switches on the switch board. 
For UPS to use, turn on its switch on its front side ( some times on the backside)    
Turn on the power button on the CPU  
Wait a while ..... It will run automatically


  

DEVELOPMENT OF ELECTRICITY......

DEVELOPMENT OF ELECTRICITY......

   Who had discovered first electric cell ? or, who made today's method of power generation easier? Let us have a quick view through the history of power generation.

   The first man to make a cell was Alessandro Volta in the year 1800 AD . He made a pile of  Zinc and Copper plates one after another and separating them with wet cloths dipped in Sulfuric acid. Later years electric cell was formed using the Volta's idea.

SIMPLE VOLTAIC CELL

      STRUCTURE

           Two plates one of Zinc And the other Copper is partly immersed in dilute Sulfuric Acid taken in a pot. This makes a Simple Voltaic Cell. The Copper plate becomes positive and the Zinc plate becomes negative. If we connect them with a conducting wire then electric current flows.

      WORKING

                In simple Voltaic cell Chemical energy is transformed into electrical energy. This incident was discovered by famous scientist Galvani of Italy.

   

         Change in the Solution

           Molecules of the dilute Sulfuric Acid dissociates into Hydrogen and Sulfate ions

  

                H₂SO₄↔ 2H⁺+SO₄^-2

        

Reaction at zinc Plate

              In this plate Zn atoms free two of its atomic electron and transforms into Zn ions. These electrons stay on the  Zn plate and make it negative. The Zn ions come into the solution.There it combines with Sulfate ions to form Zinc-Sulfate.

                    

                        Zn-2e↔Zn⁺² 

                               Zn⁺² + SO₄^-2  = ZnSO₄ 

       

         Reaction at Copper Plate

              The Hydrogen ions come to copper plate and take electrons from there. Hydrogen ion first turns into atom .Thus Copper plate becomes positive and Hydrogen gas is generated.

 

                        H⁺ +e=H

After this various electric cell was made. Of them Lech lance cell Lead acid cells are popular.But interesting one was the dry cells.

  DRY CELL

     To make a dry cell we need a cylinder of Zinc.Here we take Ammonium Chloride as electrolytic medium. A carbon (graphite) rod is used as the second electrode while the Zn cylinder is the first one. The electrolyte at first dissociates in to ions. Zn plays same role as in case of Simple Voltaic Cell; but this time it produces Zinc Chloride. The Carbon rod acts as copper plate in Simple Voltaic Cell. But here along with Hydrogen Ammonia is generated.

The reactions occur in the dry cell is as follows: 

NH₄Cl↔NH₄⁺+Cl^-

Zn-2e↔Zn⁺² 

Zn⁺²  + 2Cl^- =ZnCl₂ 

2NH₄⁺+2e=NH₃+H₂

WHAT ELECTRIC CURRENT IS....

CONDUCTOR OF ELECTRICITY

           All matter does not conduct electricity well.It is well known that metals conduct well.The fact can be well explained by the theory of free electrons.Metals have valencies 1,2 or 3; that means atoms of metal have 1,2 or 3 electrons at the outermost shell.So metallic atoms have a tendency to detach the outermost electrons from the atom to acquire the electronic structure like the "Noble Gas". Due to heat energy these electron become free from the atom.As a result electrons and positively charged atoms (Cations) are generated.These electrons can move freely within the metallic surface and are called "the FREE ELECTRON"). These electrons give rise to current electricity.

          If we apply potential difference at the ends of a conductor then these free electrons moves from lower potential to the higher potential region.This gives rise to electric current from higher to lower potential.There are two types of electrical flow- 1.DC

                                                 2.AC

DC CURRENT :

         The electric current in which current flows in only one direction irrespective of time ; then the flow is known as DC( Direct Current). Here the potential difference does not vary with time, also the current does not vary.

AC CURRENT :

         The electric flow where the magnitude of current as well as of the potential difference changes sinusoidally with change in time is called the AC (Alternating Current). Instant magnitude of AC Voltage and current can be represent as

       V(t) = Vo Sin (wt)

And E(t) = Eo Sin (wt)

       Here Eo And Vo is called the peak value; w is called angular frequency.

           Time gap, between two consecutive positive or negative peaks, is called "TIME PERIOD". Reciprocal of this time period is called the frequency. The  frequency of a proper AC signal is 50/sec.

EXPLANATION OF AC WAVEFORM

             Famous scientist Michael Faraday said that If there is relative motion between a magnetic field and closed conducting loop then electric current is generated. This happens as magnetic flux density linked with the loop changes continuously with time.

          The following figure how the current is generated due to movement of a magnet into a loop

           If "B" be the magnetic field flux density, "A" be the area of the loop, θ be the angle between the magnetic lines of force and the perpendicular to the loop and "n" be the no. of turns of the loop then magnetic flux linked with the loop is 

                             Φ = nBA Cos(θ)   ................................(1)

       In a dynamo a magnetic shaft rotates within a rectangular coil.Thus the angle θ changes from 0 to 2л

    Then the induced emf linked with the loop is , 

                                    E = - dΦ/dt

                                       =  nBASin(θ) dθ/dt

                                       =  nBAωSinθ 

                                                           Where ω is the angular frequency of rotation                                                             =  Eo Sinθ .............................(2)

 MORE ABOUT AC

       1.AVERAGE VALUE

                           The average value of DC is constant but average value of AC averaged over the full cycle is zero.The average is done as follows :

       <E> =( ∫E(t) dt )/ ∫dt

               =(∫EoSinθdt)/ ∫dt

               =(∫Eo Sin (ωt) dt)/ ∫dt   , the limit of both the int. being  0 to T (time period)

               =0

        Average value of AC emf is non zero over a half cycle.In that case both of the above integration is done with lower limit 0 and upper limit T/2.

       2. RMS VALUE

         The rms value of AC emf is given as 

         Erms =√( ∫Eo²Sin²θ dt/ ∫dt) 

                 =√( ∫Eo²Sin² (ωt)dt/ ∫dt)         limit of integrations 0 to T

                  =(Eo) /√ 2

        *NB>* Thus we can understand why AC is more dangerous than DC. Here we see the peak value of AC emf Eo= √2 Erms. When we speak about 220 Volt AC then 220 Volt is its rms value. Therefore the peak value is 220√2=311 Volt (aprox.). But in DC 220 Volt means its peak value is 220 Volt.                      

    Though 220 Volt DC is not good for us, 220 Volt AC is more harmful.

  

DISCOVERY OF ELECTRICITY

HISTORY:

           About 600 BC Greek philosopher Thales observed that if AMBER (a type of resin of pine) is rubbed with fur  then it attracts paper cut into pieces.It was not then understood that why this happen?But in no time man started application of it.They found it a great way to stick balloons on the wall. Pet cats were then a useful fellow for their hairy body.

EXPLANATION

             The fact was explained later in the 17th century AD. The observation of Thales was explained as statical electrification.All matter consists of atoms.Atom contains two types of charged particle Protons and Electrons and neutral particles the Neutrons and a few elementary particles.Protons and Neutrons forms the center, the Nucleus and the Electrons moves round the nucleus in orbits.Fur the position of electron from the nucleus less the force of attraction, due to the nucleus, is on it.Thus the electrons at the furthest orbit are very loosely bounded to the atom.If we rub any matter with then these electrons may free from atom due to mechanical energy.The free electrons are received by one of the materials that were rubbed; thus both of them becomes electrified.Electrified materials can attract oppositely charged materials or neutral materials.So they attracts pieces of paper, pith ball etc.

         

             If the material that is rubbed is an insulator then the charged developed can not move through it stays there for a long time.Hence this is called STATICAL ELECTRICITY. If we rub a Conductor with wool or fur then we never see such things; because they conducts the charge developed due to rubbing.

VOLTA'S  DISCOVERY    :

              Scientist Volta was the first to develop current electricity.He did it by using 'oil of vitriol' and two types of metallic plates - one of copper (Cu) and the other zinc (Zn).  He made multiple layer of Zinc and Copper by placing one after another and separating them by  cloth and felt wet in 'oil of vitriol"  (Sulfuric Acid ) .This led to invent the first electric cell, called the Simple Voltaic Cell.

FURTHER DEVELOPMENT :

  

         
      Then as time passes more developed cells were designed. A few of them are The Leclance cell, Lead Acid cell etc.But with these cells we cannot fulfill the great requirement of electricity.

FARADAY'S DISCOVERY :

     Michael Faraday discovered that "If there is relative motion in between a magnet and a closed loop then electric current is generated in the loop.The magnitude of the current increases with velocity of movement , number of turns of the loop.

                   DYNAMO:

                             Dynamo is a device designed to generate current electricity.There is a rectangular coil      made of insulated copper wire and a strong magnet.The magnet actually forms the armature of the device.If the Armature is rotated around its axis then we get current electricity.Following is a simple diagram of a Dynamo.

              Here we get AC current.The magnitude of voltage (also current) changes sinusoidally with time.This happens because the number of the lines of force of the magnet that passes through the coil changes with time (As the is rectangular and the magnet is in circular motion).

   

             In power generation centers we actually revolve the shaft i.e. the armature of a dynamo.If we do that by Heat Then it called Thermal Power, If by Water flow then Hydel Power , If by Atomic Energy to Heat to Electric Energy then Atomic Power.            

 

Hard Disk Drive Failure :-

HDD (Hard Disk Drive) Failure or Boot Disk Failure 

(A) Here user must run the CMOS set-up for "IDE HDD auto detection".

(B) If the HDD is not detected, then user should check the connectivity of HDD controller.

(C) After fixing up the connection properly, if again the HDD is not detected then user can change the IDE channel, i.e. (that is) from IDE 0 to IDE 1.

(D) If the HDD Is Detected but system is not booting from c:/>, in that case user can first try with the transferring system booting from A:/>.

(E) If C drive display "Invalid Drive", in that case user should run the "Fdisk" command to create the partition.

(F) If the partition already exist then user can just try by making the primary Dos partition active.

(G) If the partition is made properly and system is transferred, then user should scan the entire HDD for virus problem.

(H) User also run the diagnostic tools like NDD, NE, DE, DM for checking the HDD track '0' and other sectors.

(I) After attempting all the possible reasons user must check the master-slave jumper setting for proper configuration and must check battery voltage for CMOS set-up. Even the existing HDD can be checked at another PC. In case for the problem of on-board IDE Chanel, the problem can be solved temporarily by adding an IDE-IO controller card at ISA slot of the motherboard. (Here, on-board Chanel should be disabled from CMOS set-up.) 

HOW TO AMPLIFY ELECTRIC CURRENT :-

WHAT IS AN AMPLIFIER?

An Amplifier is a device that can increase or decrease a signal.We can make an amplifier with a TRANSISTOR. A Transistor operated in CE mode can be useful for the purpose.

  

TRANSISTOR : Transistors are of two types- 1.npn & 2. pnp. Transistors are made imposing impurity to pure semiconductor.If we can impose p-type impurity from both sides to a n-type semiconductor we get a pnp type transistor ; and if we can impose n-type impurity from both side to a p-type semiconductor we get a npn  transistor.

  

 OPERATION of a TRANSISTOR : There are three modes of operations of a transistor :1.CE 2.CB 3.CC. To make an Amplifier we use CE mode operation.The circuit configuration is shown below :

Here we have two types of important characteristics of which output characteristic is needed for Amplifier.

OUTPUT CHARACTERISTICS :

    The output characteristic is the graphical representation of Collector current (Ic) Vs Collector-Emitter Voltage (Vce) keeping the input current (The Base current) fixed or constant.The following figure shows such a characteristic :

    The black st. line AB is called a load line .Using the biasing of the load line we prepare an Amplifier.The colored lines represent different input currents.If a small AC signal is fed to input bias then it slightly changes the input current as a result output current also changes.Input current is of the order micro-Ampere but the output current is of the order of milli-Ampere 1000 times of the input.So if take out put we get Amplified current that was fed to the input.   

 

CD-ROM Drive Is Prompted In Dos Mode But Not In Windows :-

(A) Firstly user must run the CMOS set-up for the auto detection of CD-ROM drive. If it is 'ok', then user should copy the "MSCDEXE.EXE" file from c:\WINDOWS\COMMAND> to c:\>. (It's not that all the BIOS detect CD-ROM at 'Auto Detection'.)

(B) The slave jumper is not detected by the WINDOWS default driver of CD-ROM for which the WINDOWS driver can be installed from CD-ROM driver for WINDOWS. Driver is installed by user which is comming with CD-ROM driver.

                                      CD-ROM Drive

(C) User can also check the new hardware wizard from control panel for detection of CD-ROM controler.

(D) The IRQ No. Range (reserved - 12/13/14/15) from power management set-up can be altered for accessing of CD-ROM under WINDOWS.

Display And CMOS Setup Mismatch Problem At The Time Of Running Windows. Simoultaniously System Is Restarting Automaticaly Without Entering CMOS Setup :-

(A) When POST is going then "Display Type Mismatch" , "P-233(Unknown)" , "Insufficient Memory" , "F1 To Resume" etc error massage are appeared.

(B) At first user must try with the disabling/enabling the battery jumper and then by removing and reinserting the CMOS battery. Next the RAM module can be alter changed on the RAM slots. (To follow all these setup, user must power on the PC for every Case.)

CMOS Battrie

(C) If it is possible to enter CMOS setup, user at first check the display type then "VDO BIOS Cacheable" , "System BIOS Cacheable" simultaniously which must be enabled and disable respectively. Then user should go for the VDO monitor IRQ to PCI VGA (Y/N) Y from PCI?PNP configaration.

(D) When the insufficint memory problem message is displaied but the actual memory size is ok and also counted properly at POST. Then user must load the original BIOS default from the CMOS setup.(Y/N) Y.

(E) For the unknown processer configure by BIOS at the POST , this problem can be solted by loading the best performance value of BIOS.(Y)

(F) The "F1 To Resume" problem can be solved , if all the parameters of CMOS setup is set properly.

Windows / System Hangs Intermittently

Windows / System hangs Intermittently :-

(A) Here user first check specifically the power good of SMPS (+5Volt) and actual CPU clock-speed.

(B) Next user must check the CPU fan is moving properly or not and the CPU core voltage is selected properly.

(C) user should check the access time of DRAM from advanced chip-set set-up. Here user can changed the RAM slots modules.

(D) User should observe whether the system hangs from a particular part of a particular software. Here user can guess the suspected problem may be logical of particular software or the HDD (hard disk drive) has formed the bad sector in search a region from where system gets hangs.                

(E) User must run the latest and updated virus scanner for checking throughout the HDD.

(F) If the system hangs problem is executed from the WINDOWS platform, in that case the most suspected problem in WINDOWS OS, which should be re-installed. Even the problem may exist in the application packages or any other Taylor made software for WINDOWS, then that application package should be modified by changing the software source code.

(G) If the system hangs from WINDOWS then the graphics accelerator card may be defective, specially the VGA RAM's. 

(H) The microprocessor of the main board should be inserted properly within the socket and all the peripheral connectors must be connected tightly.

(I) The add-on cards like VGA, Sound bluster or LAN must be inserted properly within the specific slots. The mounting of mother board must be proper from which it will not touch the any part of the cabinet.   

(J) The connecting points of BUS and circuit line can be cleaned by Isoprapyl solution. The earthing of the supply line must be within the range of 0.5Volt to 2Volt maximum and the line-neutral connection should be as usual.

(K) If all the attempts failed then the user should replace either RAM or Motherboard depending on the situation.

In Windows Mode Peripherals / Devices Are Not Working Properly

 

(A) The general peripherals like mouse, sound card, USB card, Internal & External Modem can not function properly in windows platform. In that case the most suspected problem exits in the improper loading of driver software, which is not linked properly with the system of windows. So user must first time try through the "device manager"  or "add new hardware wizard" from the system which is in the "Control Panel".

Control Panel

(B) Once the peripherals is installed properly with its related driver software, then obviously the OEM name or few specific symbols appeared in specific location. For example user can understand that his sound card has been installed properly by checking the OEM name of sound controller under device manager Or the symbol of the speaker at windows task bar. Now if sound dose not come out, then it is clear that the problem exist in the either in sound controller or in the speaker.

Sound Card

Windows Is Unable To Update Hardware Devices After Installation :-

(A) After the complete installation of windows, when it configure the PC for first time by checking system device, some time it is seen that the process taking time for a long period. Here user should restart the PC and observe the rest of the processing. If the same problem exist then user must try with the another EDO or SD RAM or DDR RAM module by changing. Even the problem might be existing in the Motherboard because WINDOWS can not update the drivers for motherboard components.

Motherboard

(B) The HDD track '0' might be corrupted, for which NDD or DE can be run.

CD ROM Drive

(C) User can also try with the another CD or CD ROM drive because internal '.CAB' file or Windows CD may be corrupted for updating system devices or the CD ROM drive speed is not compatible with the writing speed of that CD.

  

Shutdown And Display Problem

(A) The present generation Mbd(Motherboard) is suppose to use the flash ROM BIOS. So at first user must check the Normal/Clear CMOS jumper settings. If the jumper is set at the normal position, then display may not come after power on the P.C.(Personal Computer), for which user must set the jumper to Clear position to coming display after power on. ( The important point is that power dose not come after switch on in ATX SMPS until the standby/ suspend button from toggle switch of cabinate is set at the standby/suspend position at Mbd end.

SMPS

(B) The shutdown massage of windows dose not appear the ATX system. In the normal cabinate/SMPS, this massage may not appear also, for which ACPI (Advance Configuration Power Interface) function must be checked from power management option of CMOS setup.(Enable/Disable).

SMPS Ckt.

(C) Sometimes display dose not come also after the actual settings of CMOS jumper, in this case the CPU core voltage from the "CPU PNP" option from CMOS setup must be detected. then user must check the battery voltage and flash ROM BIOS voltage (5v,8v,12v) from Mbd.

ATM Loading Problem

ATM Loading Problem :-

    This DTP software creates the problem for windows 2nd edition- (system hangs intermittently and desktop icons can not be open) changeover problem from windows to DOS mode vice versa, most of the times explorer dose not responds for opening different system application and directories sometimes "top type keyboard installed"  message appears on the screen when any application is running or just already to open the "start button key" from keyboard dose not initialize even if the pointer is not activated (here by substitution "CTRL+ESC" is the alternative) etc.

    

    This problem is not arised in windows 98 first edition.

 The above problems are under (R&D) for windows-NT environment.