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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

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To Refresh Your Memory

In the semester, you have learnt… Combinational Logic – Truth table/schematics/Boolean

expression, SOP/POS, DeMorgan’s 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, 2’s complement

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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

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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

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Block Diagrams for Control (1)

𝐶 (𝑧 ) 𝑃 (𝑧 )

𝐺 (𝑧 )

𝑘𝑧− 1

1

1−𝑘𝑧− 1

1

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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 systemwith one pole at

1

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1

1 111 1

1 1

k kkkz kH z

k kk kz zkz k

1kk

𝑘𝑧− 1

1

1−𝑘𝑧− 1

1

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Block Diagram for Control (3) Let C(z) be “B”, P(z) be “C”, and G(z) be “B”.

A second-order systemwith two poles at

1

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1 1 1 2

1

11

11

zzkzH z

z z kz zkz

2 4

2

k k

𝑘𝑧− 1

1

1−𝑘𝑧− 1

1 1 21 0kz z

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Smart Air-conditioner Control (1) Let Troom be the current room temperature. Also, define TUTH and TLTH

be two threshold voltages set by the user, where TUTH >TLTH.

When Troom > TUTH, AND compressor is off, then the compressor of the air-conditioner should turn on to lower the room temperature.

When Troom < TLTH, AND compressor is on,then compressor of the air-conditionershould turn on, and the roomtemperature rises.

Otherwise, the operation of thecompressor stays unchanged.

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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

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Smart Air-conditioner Control (3) If instead we want to set the temperature to be lower,

with TUTH = 24 and TLTH = 22, suggest a way to achieve this adjustment.

Upper comparator: 6V to input B Lower comparator: 2.4V to input B

R1 = R - R2 = 0.6R

R1

R2

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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.

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Bidirectional Motor Driver (2) Referring to the bidirectional motor driver circuit, let kA be

the gain of the non-inverting amplifier on the left. Show that within the

operating range ofthis circuit (i.e., nosaturation), a changein Vp by ∆Vp results in achange of Vmotor bykA∆V p.

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Bidirectional Motor Driver (3) From the property of a non-inverting amplifier,

Now, When Vp becomes , the new Vmotor is

Therefore,

mp A pV k V

motor / 2mp mn A p ccV V V k V V

/ 2motor A p p ccV k V V V

/ 2 / 2motor A p p cc A p cc

A p

V k V V V k V V

k V

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Circuits and Sensors (1)

In this QTI circuit, we assume that R0 is 500Ω and that Rir is maximum when it is dark (Rmax = 1k Ω). When it is bright, Rir is minimum (Rmin = 100 Ω). Note that Vcc is 12V. The datasheet of the lamp states that it only turns on when the voltage across the lamp (VL) > 5V. Each lamp has an internal resistance of 1kΩ.

The goal is to turn on a lamp when it is dark.One of your team members suggests connectingthe terminal red directly to the lamp, terminalwhite to Vcc terminal black is grounded. Will thisconfiguration work?

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Circuits and Sensors (2)

Let RL be the resistance combining Rir and the resistance of the lamp, put in a parallel configuration.

When it is dark (Rmax = 1kΩ), the total loading resistance is RL = 500Ω, and therefore the voltage across the lamp (VL) is 6V. This is enough to turn on the lamp.

When it is bright, Rmax = 100Ω andRL = 90.9Ω.

Thus, the lamp is off.

0

90.912 1.85

500 90.9L

L ccL

RV V V

R R

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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 becomeRL = 250Ω (Parallel connectionof resistors), and thereforeVL = 4V. Therefore, it is notenough to turn on the lamps.

Therefore, a buffer should beused.

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Circuits and Sensors (4)

How the buffer should be connected?

0

0

0

0

Vp

Vp

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Difference Equations (1)

Difference equation: Transfer function: Poles:

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Difference Equations (2)

Partial fraction:

Impulse function: