FORM>SWRTHYPHASCISPELPRGHDOC h PICP69LINP6Z BOXP6Z dOVLP6Z dSWCL@BlackWhiteRedGreenBlueCyanYellowMagentafSalmonwPeachUBrownellowLight GreenwwwGrey DarkOrangeݙVanillalowGrey LightIDXHIDXDSoftSansdTitleepz,IDXDSoftSansdBlank LinefIDXDSoftSansdLetter HeadergIDXDSoftSans dIndex EntryhTOCH TOCDSoftSansdTitlenz%TOCDSoftSans dBlank LineoTOCDSoftSansdZLevel 1pTOCDSoftSans dZLevel 2qTOCDSoftSerif dLevel 3rTOCDSoftSerif dhLevel 4sTOCDSoftSerif dvLevel 5tTOCDSoftSerif d*Level 6uTOCDSoftSerif dLevel 7vTOCDSoftSerif d8Level 8wIDXPSEC1 PTPAG3pA PRN3KBVtils:APPLICATIONS/FinalWriter/FWFonts/SWOLFonts/Serif/WŬWW~WW { dELX.FormulaText{WPASDSoftSansdDocument TitlePASDSoftSansdSection Namepz??PASDSoftSansdTopic Nameq{??PASDSoftSansdSub Topic 1r|??PASDSoftSansdSub Topic 2s}??PASDSoftSans dBodyPASDSoftSans dIndented BodyTOCP!rOUTPBIBPTOIPENDPDSP2PHHFDASoftSans dSoftSans dPNDASoftSans dSHPP6Z dGRMRStrictly.For Business Writing.For Casual Writing.Custom 1.Custom 2.Custom 3.IDXLConductorsTDINFFCOP3`W)δWFDTASoftSans_Bold{WŬWΆWvtUtils:APPLICATIONS/FinalWriter/FWFonts/SWOLFonts/?c>??? c? >  @    0  @ @ @  @ 9 L08 :ַ ?)HD?ַ E)HD ַE)HD 9|D1 @  o o@ |x93o8 |o @ 3 Z90Z  |0Zp`[_ @@@  @L Po                 ?GINF SHD1PW&ǪW&W&^PTMainTBDYRULEWATTR dCHRSElectronic Servicing yr.1 pt.1ATTR dCHRS ATTR hdCHRS ATTR hdCHRS ATTR dCHRSLecture: 013.T ATTR [dCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRSTATTR hdCHRShu - 28 - November ATTR hdCHRS ATTR hdCHRS-1996RULEATTR dCHRSRULE ATTR xCHRS CAPACITORS RULEATTR dCHRSRULE ATTRdCHRSCapacitance and ChargeRULEATTR dCHRSAs the value of resistors was measured by resistance, the value of capacitors is measured by capacitance. The capacitance is proportional to the charge a capacitor is capable to store, and the formula to calculate the charge stored isRULEATTR dCHRSRULE=ATTR dCHRS ATTRdCHRS ATTR dCHRS Q = C x V ATTR dCHRS Where: ATTR dCHRS ATTR dCHRSQ = Charge = C (Coulombs)RULEInATTR+ dCHRS+ ATTR @dCHRS ATTR hdCHRS ATTR dCHRSCATTR dCHRS = Capacitance = F (Farads)RULEATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRSV = Voltage = V (Volts)RULEATTR hdCHRSRULEuATTR hdCHRS Question 1:ATTR dCHRS ATTRV dCHRSVA capacitor has a capacitance of 1F and has 10V between its terminals. Calculate the ATTR hdCHRS ATTR hdCHRS ATTR dCHRScharge it stores.RULE6nATTR hdCHRS ATTR hdCHRS ATTR hdCHRSQ = CV = 1 x 10ATTR hdCHRS-6ATTR hdCHRS x 10 = 0.00001 C = 10CRULEATTR hdCHRSRULEpATTR hdCHRS Question 2:ATTR dCHRS ATTRV dCHRSVA capacitor stores 50C and a Voltage of 100V was passed between the plates. Find its ATTR hdCHRS ATTR hdCHRS ATTR dCHRS capacitance.RULERATTR hdCHRS ATTR hdCHRS ATTR% hdCHRS%Q = CV, C = Q / V = 50 x 10ATTR hdCHRS-6ATTR dCHRS / 100 = 0.5 x 10ATTR hdCHRS-6 ATTR dCHRS F = 0.5FRULEATTR dCHRSRULEnATTR dCHRS Question 3:ATTR dCHRS ATTRV dCHRSV24C are stored in a capacitor of 8F. Find the Voltage between the terminals of the ATTR hdCHRS ATTR hdCHRS ATTR dCHRS capacitor.RULEPATTR hdCHRS ATTR hdCHRS ATTR# hdCHRS#Q = CV, V = Q / C = 24 x 10ATTR hdCHRS-6ATTR hdCHRS / 8 x 10ATTR hdCHRS-6ATTR hdCHRS = 24 / 8 = 3 VoltsRULEATTR hdCHRSRULEATTR hdCHRSRULE $ATTR$hdCHRS$Capacitors in series and in parallelRULEATTR hdCHRSRULEyATTRy hdCHRSyWhen a number of capacitors are connected in series, the total capacitance of the circuit can be found from the equation:RULE ATTRhdCHRS1ATTRhdCHRS/CATTRhdCHRSTATTRhdCHRSoATTRhdCHRStATTRhdCHRSalATTR hdCHRS = 1/CATTRhdCHRS1ATTRhdCHRS + 1/CATTRhdCHRS2ATTRhdCHRS + 1/CATTRhdCHRS3RULEATTR hdCHRSRULEATTR hdCHRSWhen a number of capacitors are connected in parallel, the total capacitance is the sum of the capacitance of all the capacitors.RULEATTRhdCHRSCATTRhdCHRSTATTRhdCHRSotATTRhdCHRSalATTRhdCHRS = CATTRhdCHRS1ATTRhdCHRS + CATTRhdCHRS2ATTRhdCHRS + CATTRhdCHRS3RULEATTRhdCHRSRULEATTRhdCHRSRULEATTRhdCHRSRULE ATTRhdCHRSColour Code of CapacitorsRULEBATTRW hdCHRSWCapacitor colour code gives the nominal value of its capacitance in picoFarads - pF (10ATTR hdCHRS-12 ATTR) hdCHRS)). Colour coded capacitors are rather small in value and are less from 1F. The digits and colour used with resistors also applies for capacitors. The preferred value of capacitors are made around the E12 series of resistors. The colour code is explained on page 218 of electronic servicing vol.1.RULEATTR hdCHRSRULEATTR hdCHRSRULE2ATTR2 hdCHRS2The colour code consists of the following 5 bands:RULEATTR hdCHRSRULEfATTR hdCHRS1: 1st digit bandATTR /dCHRS ATTR /dCHRS0-9ATTR dCHRS ATTR dCHRSAATTR dCHRS ll colours (ATTRC dCHRSCBlack, Brown, Red, Orange, Yellow, Green, Blu, Violet, Grey, White)RULE!nATTR hdCHRS2: 2nd digit bandATTR  dCHRS ATTR  dCHRS0-9ATTR dCHRS ATTR dCHRS All coloursRULE7ATTR dCHRS3: Multiplier of pFATTR dCHRS ATTR dCHRS0-6ATTR dCHRS ATTR dCHRSBlack = ATTR dCHRS10ATTR dCHRS0ATTR dCHRS to Blue = 10ATTR dCHRS6ATTR dCHRS pFATTR  dCHRS RULE-ATTR hdCHRS 4: ToleranceATTR mdCHRS ATTR hdCHRS ATTR hdCHRS0,9ATTR dCHRS ATTR dCHRSBlack = 20% - White = 10%RULE8nATTR hdCHRS5: Working VoltageATTR dCHRS ATTR dCHRS2,4ATTR dCHRS ATTR! dCHRS!Red = 250V - Yellow = 400V d.c.RULEATTR dCHRSRULERATTR dCHRS Ex1: Brown-Green-Black-Black-RedATTR /dCHRS ATTR hdCHRS ATTR hdCHRS = 15 x 1pFATTR dCHRS ATTR% dCHRS%= 15pF of tolerance 20%, 250V W.Volt.RULEWATTR dCHRSEx2: Grey-Red-Orange-White-Red ATTR QdCHRS ATTR hdCHRS ATTR hdCHRS = 82 x 10 ATTR hdCHRS3ATTR hdCHRS pFATTR &dCHRS ATTR' ,dCHRS'= 82,000pF = 82nF, 10% tol, 250V W.VoltRULE]ATTR! dCHRS!Ex3: Blue-Grey-Green-White-YellowATTR "dCHRS ATTR hdCHRS ATTR hdCHRS = 68 x 10 ATTR hdCHRS5ATTR/ dCHRS/ pF = 6,800,000pF = 6.8uF, 10%tol, 400 W.Volt. RULERATTR dCHRS Ex4: Black-Brown-Black-Black-RedATTR UdCHRS ATTR hdCHRS ATTR hdCHRS = 01 x 1pF ATTR dCHRS ATTR$ hdCHRS$= 1pF of tolerance 20%, 250V W.Volt.RULEATTR hdCHRSRULE ATTRhdCHRSLetter & Digit CodeRULEATTR hdCHRSAnother way to code the capacitance of a capacitor is by the Letter and Digit code. This does not consists of colours, but a set of 2 digits and 1 letters which corresponds to the capacitance nominal value as follows: The 2 numerical digits represents the 2 digit numerical value, while the letter represents wether the value is pica, micro, nano, etc. This code do not give the working voltage or tolerance value.RULE\JATTR) hdCHRS)the letters corresponds to the following:ATTR dCHRS ATTR hdCHRS ATTR hdCHRSpATTR hdCHRS=pico, ATTR hdCHRSnATTR hdCHRS=nano, ATTR hdCHRSATTR hdCHRS=micro, ATTR hdCHRSmATTR hdCHRS=milli, ATTR hdCHRSKATTR hdCHRS=Kilo, ATTR hdCHRSMATTR hdCHRS=Mega.RULEATTR hdCHRSRULEUATTR hdCHRS Lxx = 0.xx LATTR dCHRS ATTR dCHRS xLx = x.x LATTR dCHRS ATTR dCHRS xxL = xx LATTR dCHRS ATTR dCHRSxx0L = xx0 L, ATTR %dCHRS ATTR! dCHRS!where x is a digit, L is a letterATTR hdCHRS RULEATTR hdCHRSRULEJATTR hdCHRSEx1: 15 = 0.15F (or 150nF)ATTR adCHRS ATTR dCHRS 15 = 1.5FATTR dCHRS ATTR dCHRS 15 = 15FATTR dCHRS ATTR dCHRS150 = 150F = 0.15mFATTR dCHRS RULEKATTR hdCHRSEx2: K56 = 0.56K (or 56) OhmsATTR dCHRS ATTR dCHRS5ATTR dCHRS 6 = 5.6KATTR dCHRS ATTR dCHRS 56K = 56KATTR dCHRS ATTR dCHRS560KATTR dCHRS = 560K = 0.56M OhmsRULEATTR hdCHRSRULEeATTRe hdCHRSeOne can say that the letter position represents the position of the decimal point in the digit value.RULEATTR hdCHRSRULE ATTRhdCHRSFunctions of a capacitorRULEATTR hdCHRSEvery electrical or electronic component performs certain functions. These functions are the characteristix of that particular component and so we cannot replace say a capacitor with a resistor or inductor.RULEATTR hdCHRSRULE"ATTR" hdCHRS"The functions of a capacitor are: RULEXATTR hdCHRS1> ATTRk hdCHRSkStore electricity in the form of electric charge and so between the plates of the capacitor there will be ATTR hdCHRSan electric field. ATTR dCHRS RULEATTR hdCHRSRULE|ATTR| hdCHRS|2> Blocks d.c. current if connected in series with the d.c. supply, but allows A.C. to pass if the supply is changed to a.c.RULEATTR hdCHRSRULEATTR hdCHRS3> Filter any A.C. from an A.C.+D.C. current, so that only D.C. passes. In this case the capacitor is connected in parallel with the supply.RULEATTR hdCHRSRULEATTR hdCHRSThus a capacitor can be connected in a circuit into 2 ways: in parallel or in series. In parallel, the capacitor is called the coupling capacitor, smoothing capacitor or reservoir capacitor, and filters D.C. from A.C. (used in a.c to d.c transformers). In series, a capacitor is found normally in the signal path where one wants to allow A.C. to pass but stops D.C. like in an interstage.RULEATTR hdCHRSRULE  ATTR hdCHRS CAPACITANCERULEATTR hdCHRSA Capacitor consists of 2 parallel conductor plates usually of Aluminium, separated by a thin layer of dielectric (insulator material). The capacitance of capacitors depends on the following factors:RULE4nATTR hdCHRSCATTR hdCHRS apacitanceATTR hdCHRS is ATTR hdCHRSproportional to theATTR hdCHRS plate common areaRULE[XATTR, hdCHRS,Capacitance is inversely proportional to theATTR hdCHRS distance between the plates ATTR hdCHRS(ATTR hdCHRSdielectric layer)RULE=,ATTR hdCHRSCapacitance depends upon the ATTR  hdCHRS material used for the dielectricRULEUBATTR' hdCHRS'Working Voltage is proportional to the ATTR hdCHRSdistance between the plates ATTR hdCHRS(Dielectric layer)RULEATTR hdCHRSRULEATTR hdCHRSThe value of the capacitor mainly depends on the area and the distance between the plates but the working Voltage of the capacitor depends only on the distance between the plates. In fact the Capacitance van be calculated by the following equation:RULEATTR hdCHRSRULE_vATTR hdCHRS ATTRhdCHRS C = EATTRhdCHRS0ATTRhdCHRS . EATTRhdCHRSrATTRhdCHRS . AATTRdCHRS ATTRhdCHRS ATTRhdCHRS ATTRhdCHRSEATTRhdCHRS0ATTRdCHRS =ATTR(dCHRS ATTR3 dCHRS3A constant, known as the permittivity of free spaceATTR dCHRS (8.85 x 10ATTR hdCHRS-12 ATTR hdCHRS)RULEWATTRhdCHRS dATTREdCHRS ATTRhdCHRS ATTRhdCHRS ATTRhdCHRSEATTRhdCHRSrATTRdCHRS = ATTRdCHRS ATTR= dCHRS=Relative permittivity of the material used for the dielectricRULE ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTRhdCHRSA =ATTR9dCHRS ATTR 9dCHRSArea of plates in mATTR 9dCHRS2 RULEFATTRhdCHRS ATTRhdCHRS ATTRhdCHRS ATTRhdCHRS ATTRhdCHRS ATTRhdCHRSd = ATTRdCHRS ATTR dCHRSDATTR dCHRSistaATTR6 dCHRS6nce between plates (or dielectric thickness) in metresRULEATTR hdCHRSRULE #ATTR#hdCHRS#Charge and Discharge of a CapacitorRULEATTR hdCHRSRULEiATTRi hdCHRSiA non charged capacitor gives a temporary short circuit for a small time. In fact when connecting an ohmeter with the uncharged capacitor, it will give a steady 0Ohms deflection, which slowly fades back to its orginal position hence at infinity. If the short circuit persists (at 0 Ohms) the capacitor is shorted (acts as a conductor), and needs to be replaced.RULEATTR hdCHRSRULEATTR hdCHRSWhen a capacitor is fully charged and its Voltage and polarity are equal to those of the Ohm-meter, the capacitor will indicate infinity resistance, as it will act as an insulator to d.c. Note that a capacitor can be charged and discharged only via a d.c. circuit.RULEATTR hdCHRSRULE0ATTR0 hdCHRS0If the switch is moved to position 1, initially, Vr=100V, Vc=0V. As time passes, Vc starts to increase as much as Vr decrease and so, in any instance Vr+Vc=Vs (100V). After a certain time, Vc=100V and Vr = 0V, hence the capacitor is fully charged. The capacitor is charged due to flow of current, which in the capacitor, it is maximum at the moment of the initial charging, and 0 when capacitor is fully charged, hence no flow of current in the d.c. circuit. The value of the initial charging current is calculated by Vs / R (from V=IR) I = 100/1000 = 0.1 ARULEATTR hdCHRSRULEATTR hdCHRSTime Constant:RULEgATTRg hdCHRSgThe time constant of a Capacitor + Resistance circuit is the product of the Capacitance and Resistance.RULE;ATTR; hdCHRS;t.c. = CR (t=time/s, C=Capacitance/F R=Resistance/Ohms)RULEATTR hdCHRSThe time constant is that time taken by the capacitor to charge by 63.3% of the total voltage. The capacitor is fully charged after 5 times the time constant. (5 x t.c. = fully charged capacitor).RULEATTR hdCHRSRULEATTR hdCHRSFigure 12.8 (pg.174) shows a graph of how Vc increases with time while a capacitor is being charged, and figure 12.9 shows how Vc decreases with time, when a fully charged capacitor is being discharged.RULEATTR hdCHRSRULE*BATTR dCHRSNote:ATTR dCHRS ATTR$ dCHRS$When buying a capacitor from a shop one must state the capacitance, working voltage and type of capacitor. Electrolytic and tantalum capacitors a polarity sensitive (must be connected with matching polarity), whereas non-polarized capacitors (such as paper) can be connected in any direction.RMSTRULEATTR dCHRSLMSTRULEATTR dCHRS