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ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page 7CAPACITORSCAPACITORS, What do they do?Capacitors act the same as the pipe in Figure 9.When a voltage (Electrical Pressure) is placed onone lead with respect to the other lead, electronsare forced to “pile up” on one of the capacitor’splates until the voltage pushing back is equal to thevoltage applied. The capacitor is then charged to thevoltage. If the two leads of that capacitor areshorted, it would have the same effect as letting theplunger in Figure 9 move freely. The capacitor wouldrapidly discharge and the voltage across the twoleads would become zero (No Charge).Capacitors are components that can store electricalpressure (Voltage) for long periods of time. When acapacitor has a difference in voltage (ElectricalPressure) between its two leads it is said to becharged. A capacitor is charged by forcing a oneway (DC) current to flow through it for a short periodof time. It can be discharged by letting an oppositedirection current flow out of the capacitor. Considerfor a moment the analogy of a water pipe that has arubber diaphragm sealing off each side of the pipeas shown in Figure 9.What would happen if the plunger in Figure 9 waswiggled in and out many times each second? Thewater in the pipe would be pushed by the diaphragmthen sucked back by the diaphragm. Since themovement of the water (Current) is back and forth(Alternating) it is called an Alternating Current or AC.The capacitor will therefore pass an alternatingcurrent with little resistance. When the push on theplunger was only toward the diaphragm, the wateron the other end of the diaphragm moved justenough to charge the pipe (transient current). Justas the pipe blocked a direct push, a capacitor clocksdirect current (DC). An example of alternatingcurrent is the 60 cycle (60 wiggles each second)current produced when you plug something into awall outlet.Pipe Filled with WaterPlungerRubber DiaphragmSealing Center of PipeFigure 9If the pipe had a plunger on one end, as shown inFigure 9, and the plunger was pushed toward thediaphragm, the water in the pipe would force therubber to stretch out until the force of the rubberpushing back on the water was equal to the force ofthe plunger. You could say the pipe is charged andready to push the plunger back. In fact, if theplunger is released it will move back to its originalposition. The pipe will then be discharged or with nocharge on the diaphragm.SUMMARY: A capacitor stores electrical energywhen charged by a DC source. It can passalternating current (AC), but blocks direct current(DC) except for a very short charging current, calledtransient current.-6-

ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page 8CAPACITORSCAPACITORS, How are they made?pressure (low capacitance, but high workingvoltage). By making the pipe larger and keeping thestiff rubber we can achieve a device that holds alarge amount of water and withstands a high amountof pressure (high capacitance, high working voltage,large size). These three types of water pipes areillustrated in Figure 12. The pipes follow the rule thatthe capacity to hold water, (Capacitance) multipliedby the amount of pressure they can take (Voltage)determines the size of the pipe. In electronics theCV product determines the capacitor size.There are many different types of capacitors used inelectronics. Each type is made from differentmaterials and with different methods. Capacitors arealso made to handle different amounts of electricalpressure or voltage. Each capacitor is marked toshow the maximum voltage that it can withstandwithout breaking down. All capacitors contain thesame fundamental parts, which consist of two ormore conductive plates separated by anonconductive material. The insulating materialbetween the plates is called the dielectric. The basicelements necessary to build a capacitor are shownin Figure 10.Paper or Plastic InsulatorLead 1Conductive PlateLead 2Nonconductive MaterialFigure 10Lead 1Lead 2Figure 11THE METAL FOIL CAPACITORPerhaps the most common form of capacitor isconstructed by tightly winding two foil metal platesthat are separated by sheets of paper or plastic asshown in Figure 11. By picking the correct insulatingmaterial the value of capacitance can be increasedgreatly, but the maximum working voltage is usuallylowered. For this reason, capacitors are normallyidentified by the type of material used as theinsulator or dielectric. Consider the water pipe withthe rubber diaphragm in the center of the pipe. Thediaphragm is equivalent to the dielectric in acapacitor. If the rubber is made very soft, it willstretch out and hold a large amount of water, but itwill break easily (large capacitance, but low workingvoltage). If the rubber is made very stiff, it will notstretch far, but will be able to withstand higherConductive FoilSoft RubberStiff RubberLarge CapacityLow PressureLow Capacitybut can withstandHigh PressureStiff RubberLarger SizeHigh Capacity and can withstand High Pressure-7-Figure 12

ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page 9CAPACITORSDIELECTRIC CONSTANT, What is it?THE VARIABLE CAPACITORThe dielectric (rubber diaphragm in the water pipeanalogy) in a capacitor is the material that canwithstand electrical pressure (Voltage) withoutappreciable conduction (Current). When a voltage isapplied to a capacitor, energy in the form of anelectric charge is held by the dielectric. In the rubberdiaphragm analogy the rubber would stretch out andhold the water back. The energy was stored in therubber. When the plunger is released the rubberwould release this energy and push the plungerback toward its original position. If there was noenergy lost in the rubber diaphragm, all the energywould be recovered and the plunger would return toits original position. The only perfect dielectric for acapacitor in which no conduction occurs and fromwhich all the stored energy may be recovered is aperfect vacuum. The DIELECTRIC CONSTANT (K)is the ratio by which the capacitance is increasedwhen another dielectric replaces a vacuum betweentwo plates. Table 3 shows the Dielectric Constant ofvarious materials.Air, at normal pressureAlcohol, ethyl (grain)BeeswaxCastor OilGlass flint density 4.5Glycerine1251.864.671056Mica7.5Paraffin wax2.25Paper, manilaPorcelainQuartzWater, distilledTable 3To make a variable capacitor, one set of stationaryaluminum plates are mounted to a frame with asmall space between each plate. Another set ofplates are mounted to a movable shaft anddesigned to fit into the space of the fixed plateswithout touching them. The insulator or dielectric inthis type of variable capacitor is air. When themovable plates are completely inside the fixedplates, the device is at minimum capacitance. Theshape of the plates can be designed to achieve theproper amount of capacitance versus rotation fordifferent applications. An additional screw is addedto squeeze two insulated metal plates together(Trimmer) and thus set the minimum amount ofcapacitance.TrimmerFixed PlatesShaft1.5MovablePlates4.4Frame281Figure 13-8-

ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page 10CAPACITORSCAPACITANCE, How is it calculated?The amount of charge a capacitor can hold(capacitance) is measured in Farads. In practice,one farad is a very large amount of capacitance,making the most common term used micro-farad orone millionth of a farad. There are three factors thatdetermine the capacitance that exist between twoconductive plates:0.01 inchGlass K 101. The bigger the plates are (Surface Area),the higher the capacitance. Capacitance(C) is directly proportional to Area (A).2. The larger the distance is between the twoplates, the smaller the amount ofcapacitance. Capacitance (C) is indirectlyproportional to distance (d).1 inch1 inch3. The larger the value of the dielectricconstant, the more capacitance (Dielectricconstant is equivalent to softness of therubber in our pipe analogy). Thecapacitance (C) is directly proportional tothe Dielectric Constant (K) of the insulatingmaterial. From the above factors, theformula for capacitance in Farads becomes:Figure 14CAPACITOR VALUES AND MARKINGSC 0.244K A(N-1) Picofarads *dC Capacitance in Picofarads (Farad x 10-12)K Dielectric ConstantA Area of one Plate in square inchesN Number of Platesd Distance between plates in inchesExample Calculation for Capacitor shown in Figure 14.C 2.24 x (1 x 1)(2 - 1) / (.01) 224 Picofarads or0.000224 Microfarads.* If A and d are in centimeters change 0.224 to0.0885. 16V 1010mF 25VB682KK2200mF 25VThe older styles of capacitors were marked withcolored dots or rings similar to resistors. In recentyears, the advances in technology has made iteasier to print the value, working voltage, tolerance,and temperature characteristics on the body of thecapacitors. Certain capacitors use a dielectric thatrequires markings to insure one lead is always keptat a higher voltage than the other lead. Figure 15shows typical markings found on different types ofcapacitors. Table 4 gives the standard values usedand the different methods for marking these icFigure 15AxialElectrolyticChip(nomarkings)

ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page FCAPACITORSCap. Value Typical 473R05R0681041542042R2221002204701000Tolerance (%)6Markings7 5% 10% 20%–10% 30%–10% 50%–20% 80%SPECIALJKMQTZATemperatureMarkingsNP0 { 10ppm / OC}N100 { 100ppm / OC}N220 { 220ppm / OC}N820 { 820ppm / OC}Y5FY5TY5VX5FZ5Umanufacturer may use an R to represent thedecimal point. The tolerance is usually printeddirectly on the capacitors. When it is omitted, thestandard tolerance is assumed to be 80% to –20%for electrolytics. Capacitance change withtemperature is coded in parts per million per degreeC, {N220 220/1,000,000 or .022%}, or by atemperaturegraph.Seemanufacturersspecifications for complete details.Capacitor markings vary greatly from onemanufacturer to another as the above table shows.Voltages may be marked directly (200V) or coded(2D). The value of capacitance may be markeddirectly on the part as shown in columns 4 and 5(note that .001mF and 1000mF have the samemarking, but the difference in size makes the valueobvious). The number 102 may also be used torepresent 1000 (10 2 zeros). In some instances theCAPACITOR SYMBOLSFigure 16 shows the schematic symbols used to representcapacitors. The symbol indicates that the capacitor ispolarized and the lead marked with the sign must alwayshave a higher voltage than the other lead. The curvedplate, plate with sides, and minus sign also indicate thecapacitor is polarized and these leads must always be at alower voltage than the other lead. The arrow crossingthrough the capacitor indicates of capacitance is variable.-10-Figure 16Standard –PolarizedVariable

ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page 12CAPACITORSSELF TESTTHEORYCircle the letter that best fits the description.1. A flow of electrons in one direction:a) AC Voltagec) Alternating Currentb) Direct Voltaged) Direct Current7. When electrons are forced onto one plate of acapacitor:a) Polarizationc) Storageb) Discharginga) Charging2. When two conductive plates are moved closertogether Capacitance will:a) Increasec) Stay the Sameb) Decreased) Vary Downwards8. A capacitor lead that is marked with a must always be:a) Groundedc) At higher voltage thanthe other leadb) At highest voltaged) b & c3. The name given to the material between a capacitor’splates:a) Airc) Conductorb) Dielectricd) Insulator9. A small disc capacitor marked 100 has a value of:a) 100mFc) 100pFb) .00001Fd) 100F4. Electrons flowing in and out of a wire:a) AC Voltagec) Alternating Currentb) Direct Voltaged) Direct Current10. A large electrolytic capacitor marked 100 has a valueof:a) 100mFc) 100pFb) .00001Fd) 100F5. If the size of the conductive plates is increased,capacitance will:a) Increasec) Stay the Sameb) Decreased) Vary Downwards6. A capacitor will block:a) AC Voltageb) Direct VoltagePRACTICE11. If a dielectric is changed from air to distilled water thecapacitance will:a) remain the samec) decreaseb) increase 81 timesd) drop in halfc) Alternating Currentd) Direct Current12. A dielectric that stores energy with no loss:a) Does not existc) Pure Glassb) Aird) A perfect vacuumOpen the bag marked “capacitors” and fill in the table below.TypeEXTRA CREDITCapacitanceValueWorkingVoltageTable 4What happens to the total capacitance if you connect twocapacitors as shown in Figure 17. Hint, use water pipeanalogy and try to calculate equivalent if one water pipe.-11-Polarized(Y/N)10mF20mFOtherMarkings? mFFigure 17

ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page 13INDUCTORSINDUCTORS, What do they do?The electronic component known as the inductor isbest described as electrical momentum. In our waterpipe analogy the inductor would be equivalent to avery long hose that is wrapped around itself manytimes (see Figure 18). If the hose is very long it willcontain many gallons of water. When pressure isapplied to one end of the hose, the thousands ofgallons of water would not start to move instantly. Itwould take time to get the water moving due toinertia (a body at rest wants to stay at rest). After awhile the water would start to move and pick upspeed. The speed would increase until the friction ofthe hose applied to the amount of pressure beingapplied to the water. If you try to instantly stop thewater from moving by holding the plunger, themomentum (a body in motion wants to stay inmotion) of the water would cause a large negativepressure (Suction) that would pull the plunger fromyour hands.Since Inductors are made by coiling a wire, they areoften called Coils. In practice the names Inductorand Coil are used interchangeably. From the aboveanalogy, it is obvious that a coiled hose will passDirect Current (DC), since the water flow increasesto equal the resistance in the coiled hose after anelapsed period of time. If the pressure on theplunger is alternated (pushed, then pulled) fastenough, the water in the coil will never start movingand the Alternating Current (AC) will be blocked.The nature of a Coil in electronics follows the sameprinciples as the coiled hose analogy. A coil of wirewill pass DC and block AC. Recall that the nature ofa Capacitor blocked DC and passed AC, the exactopposite of a coil. Because of this, the Capacitorand Inductor are often called Dual Components.Table 5 compares the properties of capacitors andinductors.Large Hose Filledwith WaterPlungerWater PipeFigure 18CapacitorInductorBlocks Direct CurrentBlocks Alternating CurrentVoltage in Capacitor cannot change instantlyCurrent in an Inductor cannot change instantlyPasses Alternating CurrentPasses Direct CurrentQuick Voltage change produces large CurrentStores Energy in Electric FieldCurrent leads VoltageQuick Current change produces large VoltageStores Energy in Magnetic FieldVoltage leads CurrentTable 5-12-

ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page 14INDUCTORSINDUCTORS, How are they made?the coil is increased, it will take more hose to form aloop, and the amount of water will thereforeincrease. More water means a larger “apparentmass”. Inductance will also increase in a coil if thecross sectional area increases. Inductance isdirectly proportional to area.In order to understand how inductors are made, wehave to change our water pipe analogy slightly toinclude the effect of magnetic fields. Consider twopipes filled with water and small magnets attachedto the walls of the pipes with rubber bands as shownin Figure 19. The moving magnets, due to theoriginal current, pull the magnets in the second pipeand force a small current to flow in the samedirection as the original current. When the rubberbands are fully stretched, the induced current willstop, even though the initial DC current is stillflowing. If the original current is an AC currenthowever, it will induce a continuous AC current inthe second pipe because the magnets will moveback and forth, pulling the magnets in the secondpipe back and forth.Coil 1Coil 2Figure 20Consider the affect of adding more turns to coiledpipe. The amount of material to push (mass) isincreased and the amount of linkage is increaseddue to more magnets available. This causes the“apparent mass” to increase at a greater rate thanwould be expected. When making an inductor, theactual inductance is directly proportional to thesquare of the number of turns.InducedCurrentInitialCurrentFigure 19Consider the two coiled pipes shown in Figure 20.When the pipe is stretched out (increased length) asin coil 1, the adjacent turns have little affect on eachother. In coil 2 (decreased length) the magnets ineach turn of the pipe are linking and the amount of“apparent mass” in the pipe seems to increase. Inan inductor, pushing the coiled wire closer togethercauses the inductance of the coil to also increase,and stretching the coil out will lower the inductanceof the coil. In other words, the inductance of a coil isindirectly proportional to its length. If the diameter of-13-The final factor to consider when making a coil is thecore material at the center of the coil. If our pipewrapped around a material that contained manymagnets, they would also link to the magnets in thepipe.Thiswouldincrease the “apparentmass” of the water inthe pipe. The tinymagnets in the corewould rotate as shownin Figure 21 and forcethe water to keepmoving in the samedirection. Placing aniron core at the center Many tinyof an inductor will magnetsOUTdirectly increase theinductance by anINamount equal to thepermeability of theFigure 21core material.

ECK-10 REV-O 091416.qxp ECK-10 9/14/16 2:50 PM Page 15INDUCTORSINDUCTANCE, How is it calculated?Reviewing how coils are made will show thefollowing:Where:L Inductance in microhenrys1. Inductance of a coil is indirectly proportional tothe length of the coil.N Number of turnsm Permeability of core material2. Inductance is directly proportional to the crosssectional area.A Cross-sectional area of coil, in square inch

BASIC ELECTRONIC COMPONENTS MODEL ECK-10 Instruction Manual by Arthur F. Seymour MSEE It is the intention of this course to teach the fundamental operation of basic electronic components by comparison to drawings of equivalent mechanical parts. It must be u