1. 1 ENGG 1015 Tutorial Revision tutorial 11 Dec Learning Objectives Prepare for the examination News Examination Closed book; Need to bring calculators SETL (Online evaluation) HW2, HW3

2. 2 To Refresh Your Memory In the semester, you have learnt… Combinational Logic – Truth table/schematics/Boolean expression, SOP/POS, DeMorgans Theorem, K-Map, adder structure Sequential Circuit – Flip flop, Finite State Machine, clock and timing Electrical Circuit – Primitives, KCL/KVL, series/parallel connection, voltage/current divider, loading and buffer Operational Amplifier – Non-inverting amplifier Signals, Systems, Control – Signal flow graph, difference equation, operators, z-transform, feedback control Computer Systems – Binary representation, addition/subtraction for integers, 2s complement

3. Past Papers (E: Examination; H: Homework) Systems: 11H1Q1/Q2, 10H1Q1/Q2 Combinational logic: 11EQ5, 10EQ5, 11H2Q5/Q6, 10H2Q5/Q6, 11H3Q1/Q2/Q3, 10H3Q1/Q2/Q3 Sequential logic: New Electrical circuit: 11EQ3, 10EQ2, 11H1Q3/Q4/Q5/Q6, 11H1Q4/Q5/Q6/Q7 Signals and control: New Computer system: 11EQ6, 10EQ6, 11H2Q4, 10H2Q3/Q4 3

4. Lab (L: Lab; C: Checkoff) Combinational logic: L1 C1/C2/C3, L2 C1/C2/C3 Sequential logic: L3 C1/C2/C3 Electrical circuit: L4 C1/C2, L5 C1/C2/C3, L6 C1/C2/C3 Signals and control: L7 C1/C2/C3, L8 C1/SC Computer system: N/A 4

5. Block Diagrams for Control (1) 5

6. Block Diagram for Control (2) Let the controller C(z) be A, the system P(z) be C, and the sensor G(z) be D. First-order system with one pole at 6

7. Block Diagram for Control (3) Let C(z) be B, P(z) be C, and G(z) be B. A second-order system with two poles at 7

8. Smart Air-conditioner Control (1) Let T room be the current room temperature. Also, define T UTH and T LTH be two threshold voltages set by the user, where T UTH >T LTH. When T room > T UTH, AND compressor is off, then the compressor of the air-conditioner should turn on to lower the room temperature. When T room < T LTH, AND compressor is on, then compressor of the air-conditioner should turn on, and the room temperature rises. Otherwise, the operation of the compressor stays unchanged. 8

9. Smart Air-conditioner Control (2) Using the digitized information DL and DH about the room temperature, implement the air-conditioner control as a state machine. Your state machine should have 1 single output called ON. The air-conditioner compressor is turned on only when ON is TRUE. Construct based on logic 9

10. Smart Air-conditioner Control (3) If instead we want to set the temperature to be lower, with T UTH = 24 and T LTH = 22, suggest a way to achieve this adjustment. Upper comparator: 6V to input B Lower comparator: 2.4V to input B R 1 = R - R 2 = 0.6R 10 R1R1 R2R2

11. Bidirectional Motor Driver (1) Using your knowledge from labs and lectures, complete the following circuit to drive a motor in both directions depending on the value of the potentiometer. 11

12. Bidirectional Motor Driver (2) Referring to the bidirectional motor driver circuit, let k A be the gain of the non-inverting amplifier on the left. Show that within the operating range of this circuit (i.e., no saturation), a change in V p by V p results in a change of V motor by k A V p. 12

13. Bidirectional Motor Driver (3) 13

14. Circuits and Sensors (1) In this QTI circuit, we assume that R 0 is 500Ω and that R ir is maximum when it is dark (R max = 1k ). When it is bright, R ir is minimum (R min = 100 ). Note that V cc is 12V. The datasheet of the lamp states that it only turns on when the voltage across the lamp (V L ) > 5V. Each lamp has an internal resistance of 1k. The goal is to turn on a lamp when it is dark. One of your team members suggests connecting the terminal red directly to the lamp, terminal white to V cc terminal black is grounded. Will this configuration work? 14

15. Circuits and Sensors (2) Let R L be the resistance combining R ir and the resistance of the lamp, put in a parallel configuration. When it is dark (R max = 1k), the total loading resistance is R L = 500, and therefore the voltage across the lamp (V L ) is 6V. This is enough to turn on the lamp. When it is bright, R max = 100 and R L = 90.9. Thus, the lamp is off. 15

16. Circuits and Sensors (3) Now you have to connect two more lamps in parallel with the first one (i.e. 3 lamps in total). What is the problem? The total loading resistance (when it is dark) will become R L = 250 (Parallel connection of resistors), and therefore V L = 4V. Therefore, it is not enough to turn on the lamps. Therefore, a buffer should be used. 16

17. Circuits and Sensors (4) How the buffer should be connected? 17 0 0 0 0 VpVp VpVp

18. Difference Equations (1) Difference equation: Transfer function: Poles: 18

19. Difference Equations (2) Partial fraction: Impulse function: 19