(course code 2238)
First, multiple-choice questions (this topic is entitled * * 15 small questions, with 2 points for each small question and 30 points for * * *).
Of the four options listed in each question, only one meets the requirements of the topic. Please fill in the code in brackets after the title. Wrong selection, multiple selection or no selection will not be scored.
1. In the amplifier circuit, the potentials of the three electrodes of the transistor are 12V, 1 1.3V and 0V respectively, so the transistor belongs to.
A. silicon NPN type B. silicon PNP type C. germanium NPN type D. germanium PNP type
2. In the circuit shown in Figure 2, the value of the output voltage U0 is
3. The feedback amplifier circuit is shown in Figure 3, and its interstage feedback belongs to
4. The bridge rectifier capacitor filter circuit is shown in Figure 4. If the effective value of transformer secondary voltage U2=20V is known, the output DC voltage is
5. The simplest logical function of AND or type is
A.B. C. D。
6. The standard and or type of logical function is
A.σ( 1，2，5)b .σ(3，4，7)c .σ(4，5，7)d .σ( 1，4，6)
7. The simplest NOR of the logical function f (a, b, c, d) = σ (2, 3, 8, 9, 10,1,12, 13).
A.B. C. D。
8. The logical function f (a, b, c, d) = σ (1, 3, 4, 6, 9), and its constraint condition is AB+AC=0, then the simplest "AND OR" is
A.B. C. D。
9. Question 9 shows TTL logic gate, whose output f is
10. Question 10 shows the state diagram of the trigger, namely
1 1. Question 1 1 The secondary state Qn+ 1 of the flip-flop in the figure is
12. Schmidt trigger composed of 555 timers, the following statement is wrong.
A. there are two stable states. B. Timing pulses with a certain width can be generated.
C. the voltage transmission characteristic has a return difference characteristic d, which can be used for waveform shaping.
13. Single-phase bridge semi-controlled rectifier circuit with resistive load, and the phase shift range of α is
A.0≤α≤90° b . 0≤α≤ 120°c . 0≤α≤ 150° d . 0≤α≤ 180
14. The three-phase half-wave controllable rectifier circuit is charged with inductive load (not connected with current diode), and the effective value of power supply voltage is U2, so the maximum forward and backward voltage that the thyristor bears is
A.B. C. D。
15. The three-phase bridge full-control rectifier circuit is triggered by double narrow pulses, and the phase difference between the main pulse and the auxiliary pulse of each thyristor in the circuit is
A. 30 BC, 45 BC, 60 BC, 90 BC
2. Fill in the blanks (this big question is * * 10, each small question is 1 point, and * *1point)
Please fill in the correct answers in the blanks of each question. You don't score if you fill it wrong or not.
16. The triode working in the amplification region, if the IC changes from 12μA when IB increases, then its β is about 2mA.
17. In order to stabilize the output current of amplifier circuit, negative feedback should be introduced into the circuit.
18. The decimal number corresponding to hexadecimal number (6E) 16 is.
842 1BCD corresponds to 19. 242 1BCD code (110001011).
20. The NAND gate with positive logic consent is the gate with negative logic consent.
2 1. A monostable trigger composed of 555 timers. R and C are external timing elements, and the control terminal is grounded through the bypass capacitor, so the output pulse width TW=.
22. In order to ensure the safe and reliable work of thyristor, measures should be taken to limit di/dt and.
23. According to the nature of DC power supply, inverters are divided into current source type and current source type.
24. For various thyristor converters, the commonly used commutation methods are power supply commutation, forced commutation and commutation.
25. There are two modulation methods for DC chopper load voltage, namely pulse width modulation and modulation.
Three, analysis and calculation (this big topic ***8 small questions, each small question 5 points, ***40 points)
26. A circuit composed of an ideal operational amplifier is shown in Figure 26(a). The zener diode VDZ has a regulated voltage Uz of 6V, and the forward turn-on voltage can be ignored. Input voltage UI =10 sin Ω t (v), and its waveform is shown in Figure 26(b). Try to draw u0 1 and u02 waveforms corresponding to ui waveforms, and mark the amplitudes of u0 1 and u02.
27. The complementary symmetrical power amplifier circuit is shown in Figure 27. Saturation voltage drop of transistors VT 1 and VT2 |UCES|≈3V.
What are the functions of (1) diodes VD 1 and VD2?
(2) Calculate the maximum undistorted output power POM and efficiency η of the circuit.
28. Analyze the logic function of the logic circuit shown in Figure 28. In the figure, 74LS 138 is an integrated 3-8 line decoder. It is required to write the output logic formula, write the truth table and explain its logical function.
29. Question 29(a) shows the circuit composed of edge T flip-flops.
(1) Write the simplest function expression of the secondary state Qn+ 1 of the trigger;
(2) 2) The waveforms of CP, A and B are shown in Figure 29 (b). Try to draw the corresponding Q-terminal waveform. Let the initial state of the trigger be 0.
30. Try to analyze the sequential logic circuit shown in Figure 30. It is required to write the state equation of each flip-flop and draw the state transition diagram (arranged according to Q3Q2Q 1).
3 1. In the circuit shown in Figure 3 1, 74 16 1 is a synchronous 4-bit binary positive counter, an asynchronous clearing terminal and a synchronous setting terminal.
(1) Question 3 1(a) What is a decimal counter?
(2) Question 3 1(b) What is a decimal counter?
32. Question 32 shows a three-phase half-wave controllable rectifier circuit with R load.
(1) draw the waveform of ud, id, iT 1 when α = 60;
(2) Write the phase shift range of α.
33. Question 33: Charged inductive load of single-phase bridge semi-controlled rectifier circuit, ω L >; & gtr .
(1) Draw the ud waveform when α = 30, and mark the conduction interval of each tube in the figure;
(2) When vt 1 is on, the pulses of vt1and VT2 suddenly disappear, and the waveform of ud at this time is drawn, and the conduction interval of each tube is marked in the diagram.
Fourth, the design problem (this big problem ***4 small questions, each small question 5 points, ***20 points)
34. Try to design an amplifier circuit with an integrated operational amplifier with a voltage amplification factor of–10 and an input resistance of 5kΩ.
Requirements: (1) Draw a circuit diagram;
(2) Determine the circuit parameters.
35. Design a combinational logic circuit to convert three-bit binary code ABC into three-bit cyclic code XYZ. It is required to list the truth table, write the simplest output logic formula, and draw the logic diagram of XOR gate implementation.
36. Try to design a synchronous counter with D flip-flop and logic gate, and its state diagram is shown in question 36. It is required to write the driving equation and output equation of each flip-flop (no logic diagram is needed).
37. Question 37: Charged inductive load of single-phase bridge fully-controlled rectifier circuit, ω L >; & gtr, ignore the pulse of id.
It is known that when R = 1ω and α = 30, ud =60V.
(1) Calculate the transformer capacity s;
(2) Calculate the rated voltage and rated current of SCR.