PART1电路和电子工程基础A电路 英语专业VIP免费

PART1电路和电子工程基础A电路[1]Inthecaseofaresistor,thevoltage-currentrelationshipisgivenbyOhm’slaw,whichstatesthatthevoltageacrosstheresistorisequaltothecurrentthroughtheresistormultipliedbythevalueoftheresistance.就电阻来说，电压—电流的关系由欧姆定律决定。欧姆定律指出：电阻两端的电压等于电阻上流过的电流乘以电阻值。[2]Itmaybethattheinductorvoltageratherthanthecurrentisthevariableofinterestinthecircuit.或许在电路中，人们感兴趣的变量是电感电压而不是电感电流。B三相电路[1]Viewedinthislight,itwillbefoundthattheanalysisofthree-phasecircuitsislittlemoredifficultthanthatofsingle-phasecircuits.这样看来，三相电路的分析比单相电路的分析难不了多少。[2]Atunitypowerfactor，thepowerinasingle-phasecircuitiszerotwiceeachcycle．在功率因数为1时，单相电路里的功率值每个周波有两次为零。[3]ItshouldbenotedthatifthepolarityofpointAwithrespecttoN()isassumedforthepositivehalf-cycle,thenwhenusedinthesamephasordiagramshouldbedrawnoppositeto,or180outofphasewith,.应该注意，如果把A点相对于N的极性（）定为正半周，那么在用于同一相量图中时就应该画得同相反，即相位差为180。A运算放大器[1]Oneproblemwithelectronicdevicescorrespondingtothegeneralizedamplifiersisthatthegains,AUorAI,dependuponinternalpropertiesofthetwo-portsystem.对应于像广义放大器这样的电子装置，一个问题就是增益AU或者AI，它们取决于两输入端系统的内部特性。[2]ThisisoneofthekeyfeaturesofOp-Ampdesign—theactionofthecircuitonsignalsdependsonlyupontheexternalelementswhichcanbeeasilyvariedbythedesignerandwhichdonotdependuponthedetailedcharacteroftheOp-Ampitself.这是运算放大器设计的重要特征之一——在信号作用下，电路的动作仅取决于能够容易被设计者改变的外部元件，而不取决于运算放大器本身的细节特性。B晶体管[1]Putverysimplyasemiconductormaterialisonewhichcanbe“doped”toproduceapredominanceofelectronsormobilenegativecharges(N-type);or“holes”orpositivecharges(P-type).简单地说，半导体是这样一种物质，它能够通过“掺杂”来产生多余的电子，又称自由电子（N型）；或者产生“空穴”，又称正电子（P型）。[2]TO1istheoriginaltransistorshape—acylindrical“can”withthethreeleadsemergingintriangularpatternfromthebottom.Lookingatthebase,theupperleadinthe“triangle”isthebase,theonetotheright(markedbyacolorspot)thecollectorandtheonetothelefttheemitter.TO1是最早的一种晶体管形状——即一个带有三个引脚的圆柱体“外罩”，这三个引脚在底部形成三角状。首先要注意的是，“三角形”上面的引脚是基极，其右面的引脚（由一个彩色点标出）为集电极，其左面的引脚为发射极。A逻辑变量与触发器[1]Weshallnowbrieflydiscusstherelevanceofsuchterminology,andinsodoingweshallbringoutthespecialaptnessofthedesignations“true”and“false”toidentifythepossiblevaluesofavariable.现在我们将简要地讨论一下这些术语之间的关联，并在此过程中阐明用标示“真”和“假”来识别一个变量的可能值的特殊用途。[2]Justasotheralgebrasdealwithvariableswhichhaveanumericalsignificance,Booleanalgebradealswithpropositionsandisaneffectivetoolforanalyzingtherelationshipsbetweenpropositionswhichallowonlytwomutuallyexclusivealternatives.和其他处理有数字意义的变量的代数一样，布尔代数处理的是命题，而且布尔代数对于分析仅有两个互反变量命题之间的关系是一种有效的工具。[3]Thereisagenerallyprevailingattitudeindigitalsystemstoviewlogic0asabasic,undisturbed,unperturbed,quiescentstateandtoviewthelogic1stateastheexcited,active,effectivestate,i.e.,thestatearrivedat“aftersomethinghashappened.”在数字系统中，普遍的观点是把逻辑0看成一个基本的、无干扰的、稳...