電氣專業(yè)英語(yǔ)課文翻譯

1、精選優(yōu)質(zhì)文檔-傾情為你奉上An electric circuit (or network) is an interconnection of physical electrical device. The purpose of electric circuits is to distribute and convert energy into some other forms. Accordingly, the basic circuit components are an energy source (or sources), an energy converter (or converte

2、rs) and conductors connecting them. 電路（或者網(wǎng)絡(luò)）是物理電氣設(shè)備的一種互相連接。電路的目的是為了將能量分配和轉(zhuǎn)換到另外一種形式中。因此，基本的電路元件包括電源、電能轉(zhuǎn)換器以及連接它們的導(dǎo)體。An energy source (a primary or secondary cell, a generator and the like) converts chemical, mechanical, thermal or some other forms of energy into electric energy. An energy converter, a

3、lso called load (such as a lamp, heating appliance or electric motor), converts electric energy into light, heat, mechanical work and so on. 電源（原生電池或者再生電池、發(fā)電機(jī)等類似裝備）將化學(xué)能量、機(jī)械能量，熱能或者其他形式的能量轉(zhuǎn)換成電能。電能轉(zhuǎn)換器（也稱為負(fù)載，如燈泡、電熱器或者電動(dòng)機(jī)）將電能轉(zhuǎn)換成光、熱、機(jī)械運(yùn)動(dòng)等等。 Events in a circuit can be defined in terms of e.m.f. (or voltage

4、) and current. When electric energy is generated, transmitted and converted under conditions such that the currents and voltages involved remain constant with time, one usually speaks of direct-current (D.C.) circuits. 電路屬性可以根據(jù)電動(dòng)勢(shì)和電流來(lái)定義。當(dāng)電能在產(chǎn)生、傳輸和變換時(shí)，若電路中相關(guān)的電流和電壓不隨時(shí)間而變化，我們便稱其為直流電路With time-invariant

5、 currents and voltages, the magnetic and electric fields of the associated electric plant are also time-invariant. This is the reason why no e.m.f.s of self-(or mutual-)induction appear in D.C. circuits, nor are there any displacement currents in the dielectric surrounding the conductors. 在電流和電壓時(shí)不變的

6、情況下，相關(guān)電氣設(shè)備的電磁場(chǎng)也是時(shí)不變的。這就是為什么直流電路中沒有自（互）感電動(dòng)勢(shì)、以及圍繞在導(dǎo)體附近的電介質(zhì)沒有位移電流。Fig.1.1 shows in simplified form a hypothetical circuit with a storage battery as the source and a lamp as the load. The terminals of the source and load are interconnected by conductors (generally but not always wires). 圖1.1給出了一個(gè)假設(shè)電路的簡(jiǎn)單

7、形式：一個(gè)蓄電池作為電源、以及一個(gè)燈泡作為負(fù)載。電源和負(fù)載的終端用導(dǎo)體互相連接，通常這種導(dǎo)體是導(dǎo)線，但少數(shù)情況下也有例外。As is seen, the source, load and conductors form a closed conducting path. The e.m.f. of the source causes a continuous and unidirectional current to circulate round this closed path.如圖所示，電源、負(fù)載和導(dǎo)體構(gòu)成了一個(gè)閉合導(dǎo)電回路。電源的電動(dòng)勢(shì)產(chǎn)生一個(gè)連續(xù)的單方向電流在閉合回路中流通。The

8、simple circuit made up of a source, a load and two wires is seldom, if ever, met with in practice. Practical circuits may contain a large number of sources and loads interconnected in a variety of ways. 這種由一個(gè)電源、一個(gè)負(fù)載和兩根導(dǎo)線組成的簡(jiǎn)單電路在實(shí)踐中即使有時(shí)能遇到，也是很少見的。實(shí)際的電路包括很多用不同方法連接起來(lái)的電源和負(fù)載。 To simplify analysis of actu

9、al circuits, it is usual to show them symbolically in a diagram called a circuit diagram, which is in fact a fictitious or, rather, idealized model of an actual circuit of network. Such a diagram consists of interconnected symbols called circuit elements or circuit parameters. 為了簡(jiǎn)化分析，通常用電路圖來(lái)象征性地表示實(shí)際

10、的電路。實(shí)際上，電路圖是實(shí)際電路的一個(gè)假設(shè)模型，或相當(dāng)于一個(gè)理想模型。這樣的電路圖包括電路元件或者電路參數(shù)等互聯(lián)符號(hào)。Two elements are necessary to represent processes in a D.C. circuit. These are a source of e.m.f. E and of internal (or “source”) resistance RS, and the load resistance (which includes the resistance of the conductors) R (Fig.1.2). 在直流電路中，有兩

11、個(gè)元件是有必要描繪出來(lái)處理的。這就是電源的電動(dòng)勢(shì)E、內(nèi)阻RS，以及負(fù)載電阻R（其中包含了導(dǎo)體電阻）。Whatever its origin (thermal, contact, etc.), the source e.m.f. E(Fig.1.2(a) is numerically equal to the potential difference between terminals 1 and 2 with the external circuit open, that is, when there is no current flowing through the source.無(wú)論圖1.

12、2(a)中的電動(dòng)勢(shì)E的原動(dòng)力是什么（即不論是熱的、機(jī)械的還是其它什么形式），其大小就等于1、2兩端之間的開路電壓，也就是電源沒有電流通過的情況。 The source e.m.f. is directed from the terminal at a lower potential to that at a higher one. On diagram, this is shown by arrows. 電動(dòng)勢(shì)從較低電壓端指向較高電壓端，這在圖表中用箭頭表示。 When a load is connected to the source terminals (the circuit is th

13、en said to be loaded) and the circuit is closed, a current begins to flow round it. Now the voltage between source terminals 1 and 2 (called the terminal voltage) is not equal to its e.m.f. because of the voltage drop VS inside the source, that across the source resistance RS . 當(dāng)一個(gè)負(fù)載加在電源兩端（也就是說電路被加上

14、負(fù)載），同時(shí)電路閉合，就有電流開始流通。這時(shí)在電源1、2兩端之間的電壓（稱為端電壓）不等同于電源的電動(dòng)勢(shì)，因?yàn)檫@時(shí)電源內(nèi)阻RS兩端將產(chǎn)生電壓降VS。 Fig.1.3 shows a typical so-called external characteristic of a loaded source (hence another name is the load characteristic of a source). As is seen, increase of current from zero to II1 causes the terminal voltage of the sou

15、rce to decrease linearly 圖1.3表示帶負(fù)載電源的一個(gè)典型的外特性（由于電源帶負(fù)載，所以也稱為電源的負(fù)載特性）。如圖所示，當(dāng)電流從0增加到I1時(shí)，引起電源端電壓的線性減小。In other words, the voltage drop VS across the source resistance rises in proportion to the current. This goes on until a certain limit is reached. Then as the current keeps rising, the proportionality

16、between its value and the voltage drop across the source is upset, and the external characteristic ceases to be linear. 換句話說，橫跨電源內(nèi)阻的電壓降與電流成比例的增長(zhǎng)，這種增長(zhǎng)趨勢(shì)一直持續(xù)到一個(gè)特定的限值。然后當(dāng)電流繼續(xù)增加時(shí)，電流值與橫過電源的電壓降之間的比例關(guān)系被擾亂，使得外特性終止線性關(guān)系。This decrease in voltage may be caused by a reduction in the source voltage, by an increas

17、e in the internal resistance, or both. The power delivered by a source is given by the equality PS=EI, where PS is the power of the source.電源1、2兩端電壓的減小可能是由于電源電壓的減小或電源內(nèi)阻的增加引起的，也可能是兩種情況共同引起的。電源提供的功率由等式PS=EI表示，其中PS是電源的功率。It seems relevant at this point to dispel a common misconception about power. Thus

18、 one may hear that power is generated, delivered, consumed, transmitted, lost, etc. In point of fact, however, it is energy that can be generated, delivered, consumed, transmitted or lost. 這個(gè)公式恰當(dāng)?shù)叵藢?duì)功率的一個(gè)普遍的誤解。例如有人可能聽過功率被產(chǎn)生、釋放、消耗、傳輸、損耗等等。然而，實(shí)際上是能量才能夠被產(chǎn)生、釋放、消耗、傳輸或損耗。Power is just the rate of energy

19、input or conversion, that is, the quantity of energy generated, delivered, transmitted etc per unit time. So, it would be more correct to use the term energy instead of power in the above context. Yet, we would rather fall in with the tradition.功率只是能量輸入或者轉(zhuǎn)換的比率，也就是說，單位時(shí)間內(nèi)產(chǎn)生能量、釋放能量、傳輸能量的數(shù)量。因此，在上文中用能量這

20、個(gè)術(shù)語(yǔ)代替功率會(huì)更準(zhǔn)確些。但是，我們一般采用傳統(tǒng)的說法。The load resistance R(Fig.1.2(b), as a generalized circuit element, gives an idea about the consumption of energy, that is, the conversion of electric energy into heat, and is defined as P=I2R.In the general case, the load resistance depends solely on the current through

21、the load, which in fact is symbolized by the function R(I).負(fù)載電阻R作為一個(gè)普遍的電路元件，給出了能量消耗的概念，也就是電能轉(zhuǎn)化成熱能，定義為P=I2R。一般情況下，負(fù)載電阻只由流過負(fù)載的電流決定，用方程R(I)表示。By Ohms law, the voltage across a resistance is V=RI.In circuit analysis, use is often made of the reciprocal of the resistance, termed the conductance, which is

22、 defined as g=1/R.從歐姆定律可知，電阻兩端的電壓表示為V=RI。在電路分析中，經(jīng)常使用電阻的倒數(shù)，稱為電導(dǎo)，定義為g=1/R.In practical problems, one often specifies the voltage across a resistance as a function of current V(I),or the inverse relation I(V) have come to be known as volt-ampere characteristics.在實(shí)際問題中，通常規(guī)定橫跨電阻的電壓為關(guān)于電流的方程V(I),或者是反比關(guān)系I(V

23、)，這就是眾所周知的伏安特性。Fig.1.4 shows volt-ampere curves for a metal-filament lamp V1(I), and for a carbon-filament lamp V2(I). As is seen, the relation between the voltage and the current in each lamp is other than linear （nonlinear）. The resistance of the metal-filament lamp increases (with increase of cur

24、rent), and that of the carbon-filament lamp decreases with increase of current.圖1.4給出了金屬絲燈泡和碳絲燈泡的伏安曲線。如圖所示，每個(gè)燈泡的電壓和電流關(guān)系并不是線性的，當(dāng)電流升高時(shí)，金屬絲燈泡的電阻增大，碳絲燈泡的內(nèi)阻減小。Electric circuits containing components with non-linear characteristic are called non-linear. If the e.m.f and internal resistances of sources and

25、 associated load resistances are assumed to be independent of the current and voltage, respectively, the external characteristic V(I) of the sources and the volt-ampere characteristic V1(I) of the loads will be linear(Fig.1.5). 包含非線性特性元件的電路稱為非線性電路。如果假定電源的電動(dòng)勢(shì)和內(nèi)阻以及相連的負(fù)載電阻分別與電流和電壓無(wú)關(guān)，那么電源的外特性V(I)和負(fù)載的伏安特

26、性V1(I)將是線性的（如圖1.5所示）。Electric circuits containing only elements with linear characteristic are called linear.Most practical circuits may be classed as linear. Therefore, a study into the properties and analysis of linear circuits is of both theoretical and applied interest. 只包含具有線性特性的元件的電路稱為線性電路。很多應(yīng)

27、用電路都?xì)w類為線性電路，因此，對(duì)線性電路的特性和分析的學(xué)習(xí)具有理論和實(shí)際應(yīng)用的雙重意義。An operational amplifier may be treated as a single electronic component with input and output terminals, rather as transistor is. The amplifier itself consists of a number of transistor stages such as those described in other lesson, fabricated and interc

28、onnected on a single substrate, and the user has access to a limited number of terminal points. Thus, of most interest from the applications point of view are the terminal characteristics.運(yùn)算放大器可以看做一個(gè)具有輸入端口和輸出端口的單個(gè)電子元件，就像晶體管那樣。放大其本身由多級(jí)晶體管組成，這樣的多極晶體管在前述課程中已經(jīng)介紹，他們制作和連接在一塊基板上，有幾個(gè)引出端可供客戶使用。從使用的角度看，人們感興趣的

29、是端口特性。The name operational amplifier came about from the use to which early versions of the amplifiers were put, which was to provide electronic analogs of mathematical operations such as addition, Subtraction, Multiplication, Integration etc. Present-day usage is very much wider scope but the popul

30、ar name “op-amp” persists.運(yùn)算放大器這個(gè)名字起源于早期放大器的用途，他被用來(lái)進(jìn)行一些電子模擬數(shù)學(xué)運(yùn)算，例如，加減乘積分等，如今它的使用范圍已大大擴(kuò)展，但運(yùn)算放大器這個(gè)通用名字卻流傳下來(lái)。The operational voltage amplifier is represented schematically by the triangular symbol. A0 is the voltage gain from differential input to single-ended output and is always a positive number. Ph

31、ase reversals are taken into account at the input terminals, which is the reason why these are labeled + and -. The voltage at each terminal, including the output, may be referred to common reference, usually ground, and unless otherwise stated, this common reference will be assumed. Thus, letting V

32、(+) represent the voltage of the positive input terminal, we may define the differential input voltage as Vid=V(+)-V(-), and the output voltage is V0=A0Vid. If, however, the differential input voltage is defined as Vid=V(-)-V(+), the output voltage is V0=-A0Vid.電壓運(yùn)算放大器可用三角形符號(hào)來(lái)表示。A0表示從差動(dòng)輸入端到單一輸出端的電壓增

33、益，并恒為正值，考慮到在輸入端可能會(huì)有反向輸入的情況，所以要標(biāo)上+號(hào)與-號(hào)。每個(gè)端口包括輸出端口的電壓，都可以選一個(gè)共同的參考點(diǎn)，通常選大地。除非另有說明，否則所假定的參考點(diǎn)就是地。這樣用V+代表正相輸入端對(duì)參考點(diǎn)的電壓，而V則代表負(fù)相輸入點(diǎn)對(duì)參考點(diǎn)的電壓，我們可以將差動(dòng)電壓定義為Vid=V(+)+V(-),輸出電壓V0=A0Vid。然而，如果差動(dòng)輸入電壓定為Vid=V(-)-V(+);則輸出電壓V0=-A0Vid。Because no phase reversal takes place in the circuit, the positive input terminal is terme

34、d the noninverting terminal, and because a phase reversal dose take place in the circuit, the negative input terminal is termed the inverting terminal. These terminals will always be specified in the manufacturers data sheet for an amplifier. One or other of the input terminals may be connected to t

35、he common line, and the phase relationships still hold as shown. Note that the inverting terminal convention does not mean that the positive input must be connected to the noninverting and the negative input to the inverting; the amplifier may be used either way up, so to speak.因?yàn)楫?dāng)信號(hào)從正輸入端輸入時(shí)電路不發(fā)生反相，

36、所以稱之為同相端，而從負(fù)輸入端輸入時(shí)，電路發(fā)生反相，因此稱之為反相端。這些端口在放大器的銘牌上已注明。輸入端口的一端或其他的端都可連到參考點(diǎn)，可以看出其他相位關(guān)系仍保持不變。注意，稱反相端和同相端的慣例，并不意味著正信號(hào)輸入一定要與同相端相連，而負(fù)信號(hào)輸入一定要與反相端相連，可以說放大器可以采取其中任何一種使用方式。The basic equivalent circuit for the operational voltage amplifier is shown in fig. Ri is the differential input resistance, and will always

37、be high, usually in the megohm range. High input resistance may be achieved through the use of Darlington connected pairs in the input stage , or by using an FET differential input pair, as described in other lesson. R0 is the output resistance, and always be low, usually less then 100, for the oper

38、ational voltage amplifier. A0 is the voltage gain as defined in the previous section, and this will always be large, of the order of 106:1. For many applications, the amplifier may be represented by an voltage amplifier, for which 電壓放大器的基本等值電路如圖所示。Ri為差動(dòng)輸入電阻，切總是很大，經(jīng)常在兆歐級(jí)范圍內(nèi)。高輸入電阻可以通過在輸入端使用達(dá)林頓連接對(duì)來(lái)實(shí)現(xiàn)，或

39、如前所述，通過使用一個(gè)FET差動(dòng)輸入對(duì)來(lái)實(shí)現(xiàn)。R0為輸出電阻，并且總是很小。對(duì)電壓運(yùn)算放大器來(lái)說，通常不到100歐。A0為前幾節(jié)所定義的電壓放大倍數(shù)，他總是很大。大約屬于106:1的數(shù)量級(jí)。在許多實(shí)際應(yīng)用中，放大器可用一理想放大器來(lái)代表，這時(shí)：The concept of infinite voltage gain, or , for that matter, a very high but finite voltage gain, requires some explanation,. A voltage gain of 106:1 does not mean that a one-volt

40、 input signal would be amplified up to one million volts at the out put! In fact, the maximum out put voltage is limited by the bias supply voltage, typically 15V. However, an input signal of one microvolt will be amplified up to one volt at the output, and, because the amplifier is always used in c

41、ircuits in which a large fraction of the output voltage is fed back to the input, the differential input voltage may be assumed negligible in comparison with the feedback component, or in other words, Vid is assumed zero. This gives rise to the odd situation in which a zero input voltage, multiplied

42、 by an infinite voltage gain, results in a finite and very ordinary level output. The technique for analyzing this situation is illustrated in the next section.對(duì)無(wú)窮大電壓增益（此處即指非常大卻有限的電壓增益的概念）在此需要一些解釋。106:1的電壓增益并不代表將1V的電壓輸入信號(hào)放大成106V的輸出信號(hào)，實(shí)際上最大輸出信號(hào)電壓由偏置電源電壓所限制，典型值為正負(fù)15V。然而，一個(gè)微伏級(jí)輸入信號(hào)在輸出端將放大到1V，同時(shí)因?yàn)榉糯笃饕话阌糜?/p>

43、輸出電壓有一大部分反饋到輸入端的電路中，所以差動(dòng)輸入電壓與反饋部分比可忽略不計(jì)，或者換句話說，Vid假定為0。這樣就產(chǎn)生一個(gè)奇特的現(xiàn)象，輸入電壓為0，乘以一個(gè)無(wú)窮大的電壓增益，得到一個(gè)有限的常規(guī)輸出電壓，這種情況的分析技巧將在下一節(jié)中闡述。The basic inverting amplifier circuit is shown in fig, in which ideal operational voltage amplifier is assumed. The input voltage Vi is fed to the inverting terminal through a resi

44、stor R1, and the noninverting terminal is connected to ground (or the common reference line). Feedback from output to input occurs through resistor R2. Now, because Vid=0 for the ideal amplifier, the inverting terminal is at the same potential as the noninverting terminal, and is termed a virtual gr

45、ound. Because of the virtual ground, the input loop voltage equation may be written as Vid=i1R1. For the same reason, the output voltage loop equation may be written as V0=i2R2. Because Ri is assumed infinite, the input current ii is zero, and, therefore i1=-i2. Collecting and rearranging gives for

46、the terminal voltage gain:基本反向放大器的電路如圖所示，其中假設(shè)了一個(gè)理想的電壓運(yùn)算放大器，輸入電壓Vi通過一電阻R1輸?shù)椒聪喽耍⑶彝喽酥苯咏拥兀ɑ蛘呓拥焦矃⒖季€上）。輸出端到輸入端的反饋電壓出現(xiàn)在電阻R2上。因?yàn)閷?duì)理想放大器來(lái)說，Vid=0，因此其反相端與同相端電勢(shì)相等，并稱為虛地。因?yàn)槭翘摰兀斎牖芈冯妷悍匠瘫憧蓪懗赏瑯虞敵鲭妷悍匠炭蓪懗?。因?yàn)橐呀?jīng)令r1無(wú)限大輸入電流為0，所以整理后得端口電壓增益The significance of this result is that the terminal voltage gain, which is the us

47、able voltage gain, is independent of the parameters of the amplifier, and depends only on the external components R1 and R2. Had A0 been assumed large but finite, the terminal gain would be reduced approximately by a factor(1-1/A0), and it can be seen that with A0 of the order of 106:1 this factor i

48、s very close to unity. It is also assumed in the ideal amplifier that the output resistance is zero so that zero voltage drop results, internal to the amplifier. A0 is known as the open loop gain because it is the voltage gain which would result with the feedback loop open; the results of feedback w

49、ith amplifiers of finite A0 are described in other lesson.這個(gè)結(jié)論的意義在于端電壓增益（這是很有用的電壓增益）與放大器的參數(shù)無(wú)關(guān)，而只取決于外部元件R1和R2.若A0真的假定為很大但有限，端口電壓增益就會(huì)大致下降一個(gè)系數(shù)（1-1/A0）。可以看出，由于A0屬于106:1數(shù)量級(jí)，因此這個(gè)系數(shù)非常接近于1.在理想放大器中，假定輸出電阻為0，這樣在放大器內(nèi)部電壓將為0.因?yàn)锳0是在反饋回路開路時(shí)得出的電壓增益，所以他定義為開環(huán)增益。對(duì)于A0為有限的放大器反饋結(jié)果將在其他課中講述。 Practical comstraints limit the

50、 ration of R2/R1 to about 106:1 maximum. Offset problems, discussed in section 2.15, place an upper limit on R2 and R1 must be large enough compared with the signal source resistance for the latter to be ignored. In practical circuits, R1 usually ranges between 1.0k and 10.0k.In carrying out the sig

51、nal analysis it is not necessary to show the DC bias supply, but of course this must be provided.實(shí)際條件限制了R2/R1的值最大只能約為1000:1. 2.15節(jié)中討論的偏置問題限制了R2的上限，而R1與信號(hào)源的電阻相比要足夠大，以便后者可以忽略不計(jì)。在實(shí)際電路中，R1通常在1.0-10.0k范圍內(nèi)。在進(jìn)行信號(hào)分析時(shí)，沒有必要畫出直流偏置電壓，但這個(gè)電壓當(dāng)然是必須的。The integrator circuit produces an output voltage which is proport

52、ional to the integral of the input voltage. This is the inverse mathematical operation to that of differentiation.The lower limit on the integration is taken as zero time, which of course is arbitrary, and the initial voltage on the capacitor, Vc(0), takes into account all the charge accumulated pri

53、or to the chosen time origin. Since the capacitor may be allowed to charge for any arbitrary time t, the upper limit on the integral is the time variable t so that Vc itself is a function of time. This is often shown by use of a “dummy variable” for the time in the integrand. Denoting the dummy vari

54、able by the symbol t, we find that Eq.(2.5) may be written as積分器電路產(chǎn)生一個(gè)與輸入電壓的積分成正比例的輸出電壓，他是微分運(yùn)算的逆運(yùn)算。式中積分下限為0，當(dāng)然這不是強(qiáng)求的。電容的初始電壓計(jì)及了起始時(shí)間之前的所有充電結(jié)果。由于電容允許充電到任意時(shí)刻t，因此積分上限為時(shí)間變量t，這樣Vc便為時(shí)間t的函數(shù)。這一點(diǎn)可以從積分時(shí)間中常用啞變量表示看出來(lái)。若用符號(hào)t表示啞變量，可以寫成However, where there is no risk of confusion, the simpler notation of Eq.(2.5) wi

55、ll be used.Figure (omitted) shows how the operational voltage amplifier may be arranged as an integrator circuit. Application of the virtual ground concept givesand.然而在不發(fā)生混淆的情況下，可以使用比較簡(jiǎn)單的式子。圖顯示了電壓運(yùn)算放大器怎樣被組成積分電路的，由虛地概念可得出。以及與方程聯(lián)立可得Thus, the output voltage is proportional to the integral of the input

56、voltage, the constant of proportionality being1/(-RC). This is also the gain of the integrator, and as with the differentiator, it keeps the equation dimensionally correct. 因此，輸出電壓與輸入電壓的積分成正比，比例系數(shù)為。這也就是積分器增益，對(duì)于微分器其量綱也是相同的。A microcomputer interface converts information between two forms .Outside the

57、microcomputer the information handled by an electronic system exists as a physical signals, but within the program , it is represented numerically . The function of any interface can be broken down into a number of operations which modify the data in some way ,so than the process of conversion betwe

58、en the external and internal forms is carried out in a number or steps.微機(jī)接口實(shí)現(xiàn)兩種信息形式的交換。在計(jì)算機(jī)之外，由電子系統(tǒng)所處理的信息以一種物理信號(hào)形式存在，但實(shí)際程序中 ，它是用數(shù)字表示的。任一接口的功能都可分為以某種形式進(jìn)行數(shù)據(jù)變換的一些操作，所以外部和內(nèi)部形式的轉(zhuǎn)換是由許多步驟完成的。This can be illustrated by means of an example such as than or Fig 1,which shows an interface between a microcompute

59、r and a transducer producing a continuously variable analog signal. transducers often produce very small out requiring amply frication, or they may generate signals .in a form that needs to be converted again before being handled by the rest of the system .For example ,many transducers these variable resistance which must be converted to a volt