【正文】 制電器。 為了避免出現(xiàn)飽和失真和截止失真，可以調(diào)節(jié)電阻 RB、 RC或電源 UCC，使靜態(tài)工作點(diǎn)沿負(fù)載線移動(dòng)或改變負(fù)載線的斜率，而使靜態(tài) 工作點(diǎn)移到合適的位置。時(shí)鐘下降沿到來(lái)后產(chǎn)生輸出。 解：直流電源作用時(shí) XL=ω L=0， R=40/4=10Ω 交流電源作用時(shí) Z=IU=10220=22Ω XL= 22 RZ ? = 22 1022 ? = L=fXL?2= 圖 4所示電路中，已知電壓表的讀數(shù)為 15V，電流表的讀數(shù)為 1A， R=5Ω，電源的角頻率ω =200rad/s，求電感 L，和電路消耗的功率。試求 ： （ 1）靜態(tài)工作點(diǎn) IBQ＝？， ICQ＝？ UCEQ＝？ （ 2）電壓放大倍數(shù) Au=? 圖 3 答： IBQ=,ICQ＝ 2mA， UCEQ＝ ； Au=β RC / rbe=－ 100?2?103/?103＝－ 125 判斷圖 4（ a）和（ b）所示電路能否不失真地放大交流信號(hào)，并說(shuō)明原因。 13 （ a） （ b） 圖 7 答：圖示電路為標(biāo)準(zhǔn)減法器，直接運(yùn)用公式即可得所求： u0=RR（ ui2 ui1） = ui2 ui1 據(jù)此可畫(huà)出輸出波形如下圖所示 圖 8 所示為兩級(jí)運(yùn)放電路，已知 R1=RF1=10k?,R2=R3=RF2=20k?， uI1=1V 和 uI2=，計(jì)算電路輸出電壓 uO。s illustration books first appeared in the 1600s in Europe. Their passage to China, however, took much longer, roughly 300 years. In China, children39。s banks. A real danger now looms of Greece exiting the euro, which might derail the global economic recovery and damage the long term viability of the euro as a currency. However, such a tragedy is neither certain nor unavoidable. The EU should shoulder its responsibility to prevent the Greek crisis from overshadowing the fragile global recovery. As a major customer and supplier of the 28 nation EU, and a 15 responsible longterm holder of Eurobonds, China39。s national airliner. Garuda offers three nonstop flights between Beijing and Bali, and four each week between Beijing and Jakarta. There are daily flights from Guangzhou, in Guangdong province, and Shanghai to Jakarta as well. It takes from six to eight hours on a nonstop flight to reach Indonesia from China. Indonesia is home to more than 17,000 islands. Tourists can tour Yogyakarta to see Prambanam and Borobudur, two historical and religious sites, and explore the local handicraft markets. The base of a volcano, Bandung, which is also known as the Paris of Java, is ideal for adventureseekers. Many ecotourism destinations, such as Toba Lake in Sumatra, Tanjung Puting National Park in Kalimantan and Bunaken in Manado, are places the embassy official remends for tourists. Indonesia boasts worldclass surfing facilities along the shores of Sumatra down to Nusa Tenggara Islands. Recently, Lombok, a sister island east of Bali has gotten so much attention from Chinese travelers that some travel agencies are offering twin packages for Bali and Lombok. The best time to visit Bali is from May to October, when it doesn39。 186。 186。 186。 圖 1 答：置位又稱為置 1，其過(guò)程如下： 置位功能：當(dāng) S=0、 R=1 時(shí)，置位端為有效低電位，使與非門(mén) U1 輸出高電位，實(shí)現(xiàn)置位功能，即 Q=1。 3．三極管工作在放大狀態(tài)，保證信號(hào)失真不超過(guò)允許范圍。 怎么表示三相異步電動(dòng)機(jī)的起動(dòng)能力？三相異步電動(dòng)機(jī)在正常工作時(shí)，電源電壓所允許的波動(dòng)范圍是多少？ 一般用異步電動(dòng)機(jī)起動(dòng)轉(zhuǎn)矩與額定轉(zhuǎn)矩的比值 Tqd /TN 來(lái)表示電動(dòng)機(jī)的起動(dòng)能力，通常情況下，異步電動(dòng)機(jī)起動(dòng)能力取值 Tqd /TN 在 ~ 之間。 何為三要素？自行在正弦交流電量瞬時(shí)波形圖上標(biāo)出 3 要素。 A. 基數(shù) B. 權(quán) C. 系數(shù) 3． 異或運(yùn)算表達(dá)式為 : F=A?B =（ C ）。 A. 正向 C. 反向擊穿 三極管處于放大狀態(tài)時(shí)，其集電結(jié)處于（ B ）。 A. 電容 B. 電感 C. 電阻 已知電路某元件的電壓 u和電流 i分別為 u=10cos（ω t+200） V， i=5sin（ω t+1100） A，則該元件的性質(zhì)是（ C ）。今電流表指 針正向偏轉(zhuǎn)，示數(shù) 10A，有關(guān)電流、電壓方向也表示在圖中，則（ C ）正確。 + 10V ? 8Ω 2Ω ? + 10V 圖 9 2 A. 0V B. 2V C. 10V 圖 10所示電路的 I、 U表達(dá)式為（ B ）。 A A. N 極 B. S 極 C. N 極或 S極 以下說(shuō)法正確的是（ A ）。 B. 發(fā) 射極 C. 基極 放大電路引入電壓串聯(lián)負(fù)反饋，可以使輸入電阻（ A ）。 在近似恒流源供電的系統(tǒng)中，負(fù)載獲得的功率 P=UI=I2R，負(fù)載增加既是負(fù)載電壓增大，相當(dāng)于負(fù)載電阻加大。 （ 2）起動(dòng)電流不要太大，否則會(huì)對(duì)供電電網(wǎng)產(chǎn)生比較大的電壓降，從而影響電網(wǎng)上其它電氣設(shè)備的正常工作。 正向偏置時(shí)，二極管處于導(dǎo)通狀態(tài)；反向偏置時(shí)，二極管處于截止?fàn)顟B(tài)。）和或運(yùn)算（ +）互換、邏輯常量 1 與 0 互換、原變量與反變量互換（對(duì)偶規(guī)則進(jìn)行兩種互換，不需原、反變量互換）。 三、綜合題 圖 11所示電路可用來(lái)測(cè)量電源的數(shù)值及其內(nèi)阻，圖中標(biāo)出的 U和 R0 組成某實(shí)際電壓源。 一臺(tái)三相異步電動(dòng)機(jī)，磁極對(duì)數(shù) p=2，工作額定電壓為 380V，額定頻率為 50Hz，已知額定轉(zhuǎn)速為 1450r/min，求其同步轉(zhuǎn)速和額定轉(zhuǎn)差率？ 解： 1）同步轉(zhuǎn)速 n1=pf160= 25060? =1500r/min 2）額定轉(zhuǎn)差率 sN=11nnn N? = 150014501500? = 一臺(tái)三相異步電動(dòng)機(jī)，額定功率為 10KW，額定電壓為 380V，額定轉(zhuǎn) 速 980r/min，額定工作效率η =95%，額定工作電流 IN=18A，起動(dòng)能力系數(shù)為 ，過(guò)載系數(shù)為 。 說(shuō)明圖 6所示電路為何種運(yùn)算電路。 186。s artistic innovation before the advent of the Inter period. The fourth stage is featured with the spread of the Inter and the other puterized means of art innovation. The handdrawn children39。s haven, with no less than 4,000 rare birds and animals representing 200 species. With tropical forest covering over 90 percent of its area, the garden offers beautiful views of a wide range of tropical plants, flowers and fruit trees. The scenic spot about 25 kilometers from the center of Haikou offers a drive thru safari tour where you can get up close with elephants, lions and bears. The Safari on Foot area features walking trails where visitors can see the rest of the animals, including hippos and monkeys, and feed them for a small fee. Visitors also can see what happens when you breed a lion and a tiger. Two unique attractions are rare hybrids: a liger, the offspring of a mallion and a female tiger and a tigon, which is created by a female lion and a male tiger. As a teaching center of the N