* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Exercise 15_Revision on Transistor(II)
Flip-flop (electronics) wikipedia , lookup
Immunity-aware programming wikipedia , lookup
Nanofluidic circuitry wikipedia , lookup
Wien bridge oscillator wikipedia , lookup
Radio transmitter design wikipedia , lookup
Josephson voltage standard wikipedia , lookup
Oscilloscope history wikipedia , lookup
Regenerative circuit wikipedia , lookup
Analog-to-digital converter wikipedia , lookup
Integrating ADC wikipedia , lookup
Valve audio amplifier technical specification wikipedia , lookup
Surge protector wikipedia , lookup
Negative-feedback amplifier wikipedia , lookup
Current source wikipedia , lookup
History of the transistor wikipedia , lookup
Power electronics wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Wilson current mirror wikipedia , lookup
Transistor–transistor logic wikipedia , lookup
Valve RF amplifier wikipedia , lookup
Two-port network wikipedia , lookup
Power MOSFET wikipedia , lookup
Voltage regulator wikipedia , lookup
Operational amplifier wikipedia , lookup
Schmitt trigger wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Opto-isolator wikipedia , lookup
Exercise 15--Revision on Transistor ( II) 93’ MC The input is a sinusoidal voltage with a peak value of 1.5 V and a mean value of 40. zero. +6V Which one of the following waveforms best represents the variation of the output voltage with time? Vout / V A. 2k 6 15 k 4 Vout Vin 2 0 0V 1 2 Vin / V The above diagrams show an NPN transistor circuit and its input/output voltage characteristic. B. What is the current amplification factor of the transistor? A. 10 B. 30 C. 60 D. 75 E. 150 C. D 92’MC D. 30. 8 IC /mA 6 IB = 120 A 4 IB = 80 A 2 IB = 40 A E E. V CE /V The graphs show the characteristics for a transistor operating in the common emitter mode. IC is the collector current, IB is the base current and VCE is the potential difference between the collector and emitter. The current gain for this transistor is 91’ MC A. 20 43. B. 50 C. 80 D. 100 E. 150 B +6 V 2.2 k 15 k 31. The graph shows the transfer characteristic of an electronic device. V in V out 0V output voltage/V +4 An n-p-n transistor is used in the above circuit as a pulse shaper or a +3 +2 squarer. +1 V and -2 V is applied to the input, what will be the output voltage? -4 -3 -2 -1 0 1 2 3 input voltage / V When a sinusoidal voltage whose magnitude varies between +2 4 1 A. Vout 6V C. 5 mA D. 50 mA E. 500 mA 87’ MC A 43. A NPN transistor is operated as a linear voltage amplifier and the output voltage is displayed on a CRO screen as shown: time 0 B. A RL Vout 6V Rb 0 time V out V in 1.5 V -6 V V out C. V pp 3V Vout V dc 3V 0 0 time time What changes will occur when RL is slightly increased? -3 V Vdc D. Vout 2V 0 time Vpp A. decreases increases B. decreases decreases C. increases increases D. increases decreases E. no change increases 86’ MC E. 43. Vout X A 2V 0 time R -2 V 3V b c 6V S e 90 MC 39. Y +5 V In the above circuit, the sliding contact S is moved between X and Y to give different voltages across ce. Which of the following graphs best 1 k represents the variation of the collector current Ic with the voltage Vce 10 k across the emitter and the collector? A. 0 Ic The circuit above shows an NPN transistor and two resistors 10 k and 1 k connected to a 5 V d.c. supply. The current gain of the transistor is 100. What is the value of the collector current? A. 5 A B. 500 A C 0 V ce 2 B. E. 6V 6V 91 MC Ic 43. +6 V 2.2 k 0 V ce 15 k C. V out V in Ic 0V An n-p-n transistor is used in the above circuit as a pulse shaper or a squarer. When a sinusoidal voltage whose magnitude varies between +2 V and -2 V is applied to the input, what will be the output voltage? 0 V ce E A. D. Vout 6V Ic time 0 B. 0 V ce Vout 0 E. time Ic -6 V C. 0 Vout V ce 3V 44. 0 time +6 V -3 V R R R R D. Input 1 Vout R Input 2 V 2V 0 0V In the above circuit, the reading of the voltmeter is zero. the voltages applied at Input 1 and Input 2 respectively? Input 1 Input 2 A. 0V 0V B. 0V 6V C. 3V 3V D. 6V 0V 83’ MC time What should be E. Vout A 2V 0 time -2 V 30. 3 observed on the CRO. (d) If the amplitude of the superimposed sinusoidal voltage is L1 E L2 increased to 1.5 V (Figure 11.3), sketch on the same diagram the corresponding variations in output voltage, as observed E1 E2 on the CRO. The diagram shows a transistor circuit with two similar light bulbs L1 and L2. output voltage / V 6 The bulb L2 lights up brightly, but L1 does not glow at all. Which of the following could be a possible reason for this? A. The filament of L1 is burnt out. B. The cell E1 should be connected the other way round. C. The cell E2 should be connected the other way round. D. The collector current is very much less than the emitter 4 2 E. time 0 current. The base current is very much less than the emitter current. 90 IIB -2 11. (a) Draw a diagram of a circuit you could use to find the input voltage Vi/output voltage Vo characteristic of an NPN -4 transistor in the common-emitter configuration. (3 marks) (b) -6 Vo / V Figure 11.2 output voltage / V 6 6 4 4 2 2 0 1 1.5 2 3 Figure 11.1 -2 The results obtained are shown in Figure 11.1. Suppose the circuit in this experiment is to be used as an alternating voltage amplifier. suitable value. (i) -4 The input voltage must first be fixed at a Use the graph in Figure 11.1 to -6 choose the most suitable value for this fixed input Figure 11.3 (2 marks) voltage, giving an explanation, and (ii) time 0 V1 / V determine the voltage amplification. -6 (2 marks) (c) A sinusoidal voltage of amplitude 0.4 V is now superimposed on the fixed input voltage. The input and output voltages are then observed on a CRO set in AC mode. voltage is shown in Figure 11.2. The input On the same diagram, sketch the corresponding variations in output voltage as 89 IIB 11. Consider the transistor circuit in Figure 11.1 which has an 4 input-output characteristic curve as shown in Figure 11.2. (i) +6 V Sketch on Figure 11.5 the variation of the potential at point I with respect to time, from time = 0 to a time later than t3. 2.2 k (ii) 15 k With the help of the input-output characteristic curve, sketch on Figure 11.6 the corresponding variation of output the output potential at O against time. input potential at I 6V Figure 11.1 time 0 Vout /V t1 t2 t3 6 -6V 4 Figure 11.5 2 potential at O V in /V 0 0.5 1 1.5 6V Figure 11.2 time 0 (a) Account for the shape of the characteristic curve. (b) Suppose the transistor circuit shown in Figure 11.1 is (3 marks) t1 t2 t3 symbolically represented by Figure 11.3. input output Figure 11.6 Figure 11.3 on 6V S C I O off R Figure 11.4 The transistor circuit is now connected to an RC circuit, as shown, with the capacitor initially uncharged. Now at time = t1, S is switched from the OFF position to the ON position. S stays at the ON position from time = t1 to time = t3. At time = t3, S is switched back to the OFF position and remains there. It is found that at time = t2, the potential at point I has dropped below 1 V. 5 1.0 88 IIB 11. 0.5 signal voltage from signal generator / V +6 V 1 k R1 10F input 10 F output 15 k V in V out R2 time 0 - 0.5 0V - 1.0 Figure 11.3 Figure 11.1 Vout / V 6 (d) Estimate the current gain () of the transistor within the linear region. 4 (e) 2 t1 0 0.5 1.0 1.5 Vin / V output signal voltage Figure 11.2 A time Figure 11.1 shows a simple amplifier circuit which consists of a NPN silicon transistor. A' B B' The input/output voltage characteristic of t2 the transistor is shown in Figure 11.2. Figure 11.4 (a) The circuit is designed in such a way that, without any input signal, the d.c. potential at the collector of the transistor (Vout) (i) When the input signal voltage from the signal is 3 V. generator is gradually increased, the output signal (i) Explain the advantage of setting the collector voltage at voltage appears in the form shown in Figure 11.4. this value. Explain why this should happen. (ii) (ii) Estimate (2 themarks) p.d. between the collector and the Assuming that the base current is negligible, what is emitter (VCE) and the collector current (IC) during the ratio of resistances R1 to R2? time interval (2 marks) t1 and t2 when the voltage curve appears ’flat’. (b) An input signal from a signal generator is fed into the Give your answers in the table below. amplifier via a 10 F capacitor. Explain the use of such a large value capacitor. Time interval (c) Suppose the signal generator superposes on Vin a voltage varying between 0.1 V as shown in Figure 11.3. Making (2 marks) VCE IC t1 ________ ________ t2 ________ ________ use of Figure 11.2, sketch on Figure 11.3 the expected variation in voltage of the output signal. (2 marks) 6