ENGG 1203 Tutorial_05. Use of Multimeter. Lab 5 : SYSTEM. Office hours : Chow Yei Ching, CB-LG205 Thu, Fri; 15:30-17:30

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ENGG 1203 Tutorial_05 Office hours : Chow

HW : -25%/day at least after 4 days, sample

20k means max value to 20k, and the reading

there, such H for hold, etc 2 1. ADC, DAC.

Catch the trigger R, t V ref2 V ref SYSTEM

1 ENGG 1203 Tutorial_05 Office hours : Chow Yei Ching, CB-LG205 Thu, Fri; 15:30-17:30 HW : -25%/day at least after 4 days, sample answer posted for study Lab 5 : Use of Multimeter The value showing is maximum value of the range eg. 20k means max value to 20k, and the reading xx means xxk Note the LCD, if any symbols there, such H for hold, etc 2 1. ADC, DAC. 2. Counter. Catch the trigger R, t V ref2 V ref SYSTEM INPUT : Sensors, reader, bits. and etc PROCESS : Analog or Digital Control/OUTPUT : PLC, PID, Driver and etc 4

2 Design Logic Level Roff, Ron LED OFF & ON Debounce, Trigger Level, Clock & etc 5 e.g., V H : 3.3V V T : 1.15V V L : 0V 6 Lab 6 : 1. To experiment with loading effect on a DRIVING circuit; 2. To learn to use an op-amp as a buffer; 3. To begin constructing the light tracker stage. e.g. Brown, blue, green, gold 1, 6, 100k, 5% 1600k, 5% 1.6M, 5% 7 8

3 Lab 6 Can Vp go to 6V? & How? Circuits & Systems How to arrange for a system? Op-Amp Sensors + Actuators Smart System + computing V p max = V cc R pot /(R o +R pot ) 9 In parallel Same Voltage, Different in power and current In series Same Current, Different in power and voltage Building REAL system : control, actuation,.. Which configuration? 10 Example : Apple Face ID Ohm's Law Triangle & Wheel Sensing TrueDepth Camera Ohm s Law Triangle Actuating Login the PHONE

Voltage Source Current Source Ideal Voltage Source : Voltage always remains constant for any value of

Voltage across the element varies with respect to the current.

Practical Current Source : It has large value of internal resistance.

com/termionlogy/current-source-vs-voltage-source.html 13 http://www.rfwireless-world.

4 Voltage Source Current Source Ideal Voltage Source : Voltage always remains constant for any value of current passing through it. Practical Voltage Source : It has small internal resistance. Voltage across the element varies with respect to the current. Ideal Current Source : Current always remains constant for any value of voltage across it. Practical Current Source : It has large value of internal resistance. Current varies with respect to the voltage across the element Circuit Circuit Resistance in Series : Summation of all R Voltage Divider : Loadings are in series Resistance in Parallel : Parallel combination of all R Current Divider : Loadings are in parallel 15 16

Laws for Circuit Analysis There are several Laws that are known well in electronics.

zero. Kirchhoff s Voltage Law (KVL) The algebraic sum of all voltages around a closed loop equals zero Quick Checking (i) Assuming

Current Analysis Node Voltage Analysis Thevenin s Theorem Norton s Theorem Superposition Theorem.

circuits. Determine the indicated parameters for each of the following circuits.

5 Laws for Circuit Analysis There are several Laws that are known well in electronics. Ohm s Law Kirchhoff s Current Law (KCL) The algebraic sum of incoming and outgoing currents at any point in a circuit is equal to zero. Kirchhoff s Voltage Law (KVL) The algebraic sum of all voltages around a closed loop equals zero Quick Checking (i) Assuming the voltage at NODE N0 = 0, compute the voltage at node N1 in each of these circuits i.e. Matter of conservation of something Mesh Current Analysis Node Voltage Analysis Thevenin s Theorem Norton s Theorem Superposition Theorem. 17 (ii) Same line 18 Quick Checking Example 1 Assuming the voltage at node N0 = 0, compute the voltage at node N1 in each of these circuits. Determine the indicated parameters for each of the following circuits. Because the resistors are in series, the resistance between successive nodes will be proportional to the voltage between the nodes. Let an unit of resistance, R R 1 V 1 = 1R; R 2 V 2 V 1 = 1R; R 3 V 3 V 2 = 2R; R 4 V 4 V 3 = 4R; R 5 V 5 V 4 = 2R. Total : 10 R in series 19 20

Example 2 Determine R 1 and R 2 Example 2 Determine R 1 and R 2 V 1 V 2

? 21 22 Example 3 If VAB = 4V, determine relationship of R 1, R 2, R 3

and have following cases. Case (i) If V B = -1.5V then V A = 2.

6 Example 2 Determine R 1 and R 2 Example 2 Determine R 1 and R 2 V 1 V 2 = I 2 R 2 I 2 =?? 10v V 2 = I 1 R 1 I 1 =?? Example 3 If VAB = 4V, determine relationship of R 1, R 2, R 3 and R 4 in the followed cases. Solution 3(a) If VAB = 4V. and have following cases. Case (i) If V B = -1.5V then V A = 2.5V 23 By potential divider, R 1 : R 2 = 1:1, R 3 : R 4 = 1:1 You can pick any value for resistances with relationship as shown. 24

7 Solution 3(b) Case (ii) If V B = -1V, V A = 3V By potential divider, R 1 : R 2 = 2 : 3, R 3 : R 4 = 2 : 1 Example 4 For the circuit in the figure, determine i 1 to i 5. Cases (iii) If V B = -2V V A = 2V By potential divider, R 1 : R 2 = 3 : 2, R 3 : R 4 = 1 : Solution 4 Simplify the resistor networks. We apply: V = IR Series / Parallel Combinations Current Divider Solution

8 Solution 4 Example Solution 5 Solution

9 Solution 5 Solution Example 6 : (Example 5 by KCL) Solution 6 : use KCL From B to M I 1 I 2 I

10 Solution 6 : Solution 6 : I 1 I4 I 2 38 Solution 6 : Example 7 : Find Thevenin s equivalent circuit for two batteries connected in parallel V 1 = 12V, r 1 = 0.4 ohm V 2 = 12.5V, r 2 = 0.1 ohm Solution 7 : Norton s Theorem 39 40

08 ohm Equivalent voltage = 155 x 0.08 V = 12.4V Equivalent voltage? Equivalent resistance?

11 Solution 7 : Solution 7 : Battery 1 : I 1 = V 1 /0.4 = 30A R N = R Th = 0.4 ohm Battery 2 : I 2 = 12.5/0.1 =125A R N = R Th = 0.1 ohm 41 Total current = 30 A + 125A = 155A Equivalent resistance = 1/(1/ /0.1) = 1/12.5 ohm Thevenin s equivalent circuit is Equivalent resistance = 1/12.5 ohm = 0.08 ohm Equivalent voltage = 155 x 0.08 V = 12.4V Equivalent voltage? Equivalent resistance? 42 [Recall] Voltage and Current sources Superposition Theorem Obtain contribution from every particular source Voltage source : replace by short circuit Current source : replace by open source Add all contribution together for the solution Thevenin s Theorem Current source OPEN circuit Ideal current source, Z = infinity, Norton s Theorem Voltage source SHORT circuit Ideal voltage source, Z = 0 ohm Example 8 : You have connected the lamp, with Vcc = 12V. The datasheet of the lamp states that it only turns on when V L > 8V. The lamp has an internal resistance of 1k ohm. What is the range of R that would allow the circuit to function correctly with all input combinations

Solution 8 : The range of R, R L = 1kΩ When the lamp

following statement correctly describe the properties

The lamp is off only if both A & B closed, x = 0, and

Function as an AND gate 45 Ans : D 46 Example 10 How

the rest of the circuit) affect v o and i o?

12 Solution 8 : The range of R, R L = 1kΩ When the lamp is turned on, x = 1, V L > 8 Example 9 Which of the following statement correctly describe the properties of ideal voltage source and ideal current source? The lamp is off only if both A & B closed, x = 0, and V L < 8. It will function regardless of the value of R. Function as an AND gate 45 Ans : D 46 Example 10 How does closing the switch (which connects the lamp to the rest of the circuit) affect v o and i o? Example 11 Find the current i in the following circuit. 750 Ans : D Ans : D 47 48

13 Example 12 Find the current in the following circuit. Example 13 Rank values of the following circuit in ascending order. (i+1.5)10+10i-5 = A What is means for a ve current? Ans : C Ans : B Example 14 Example 15 Ans : A Ans : E 51 -END- 52

Chapter 5. Department of Mechanical Engineering

Chapter 5. Department of Mechanical Engineering Source Transformation By KVL: V s =ir s + v By KCL: i s =i + v/r p is=v s /R s R s =R p V s /R s =i + v/r s i s =i + v/r p Two circuits have the same terminal voltage and current Source Transformation