UNIVERSITY OF BOLTON. ENGINEERING, SPORTS and SCIENCES BSC (HONS) MECHATRONICS SEMESTER 1 EXAMINATION 2013/2014 ELECTRONICS FOR MECHATRONICS

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1 [kh24] UNIVERSITY OF BOLTON ENGINEERING, SPORTS and SCIENCES BSC (HONS) MECHATRONICS SEMESTER 1 EXAMINATION 2013/2014 ELECTRONICS FOR MECHATRONICS MODULE NO: MEC6005 Date: 16 December 2013 Time: 10:00 12:00 INSTRUCTIONS TO CANDIDATES: There are 6 questions. Answer 4 questions. All questions carry equal marks. Marks for parts of questions are shown in brackets. This examination paper carries a total of 100 marks. All working must be shown. A numerical solution to a question obtained by programming an electronic calculator will not be accepted.

2 Page 2 of 7 1. A series RCL circuit is given in Figure 1. Vin AC R C Vout R = 860 Ohms C = 2.2uF L = 120mH Vin = 35V 2000 Hz L Figure 1 Series RCL Circuit From the circuit given in Figure 1: a) Draw the phasor diagram showing the resistance, the reactance of the capacitor, and the reactance of the inductor, and hence calculate the magnitude and phase angle of the circuit impedance. (10 marks) b) Calculate the peak current flowing in the circuit. c) Calculate the resonant frequency of the RCL circuit. d) Calculate the peak current flowing in the circuit at the resonant frequency.

3 Page 3 of 7 2. a) A full wave rectifier circuit converts an AC supply to a pulsed DC voltage. i. Draw the circuit for a full wave rectifier including a reservoir capacitor ii. Describe using how the full wave rectifier circuit functions for each half cycle of the voltage supply. iii. Sketch the waveforms showing the effect of adding a reservoir capacitor to the output of a full wave rectifier circuit. b) A zener diode is used to produce a constant output of 5.6V from an input voltage that may vary from 10V to 12V. i. Sketch the circuit that uses a zener diode to produce the function described above. (4 marks) ii. Select appropriate component values such that the circuit will deliver a current of at least 100mA to an external load, and estimate the maximum power dissipation in the diode. (6 marks)

4 Page 4 of 7 3. a) An operational amplifier can be considered to have certain ideal characteristics which are used in the analysis of amplifier circuits containing such devices. i. Describe the characteristics of an ideal operational amplifier ii. Identify the key rules used when analysing operational amplifier circuits b) One of the standard circuits for an operational amplifier is in the non-inverting mode. i. Draw the circuit for an operational amplifier in non-inverting mode and derive from first principles an equation describing the operation of the circuit. ii. Design a non-inverting amplifier having a gain of 21. Use resistor values between 1k Ohm and 100 k Ohm in your design. (12 marks) c) Define the term Common Mode Rejection Ratio (CMMR)

5 Page 5 of 7 4. a) List the differences between a Microcontroller and Microprocessor. (4 marks) b) Briefly define the following components of a microcontroller: i. RAM ii. ROM iii. A/D converter (6 marks) c) Determine the content of PORTB after executing the following lines of code. i char A = 0x32; PORTB=0x35; PORTB =(~A); PORTB &=(0x35); ii char C = 0x12; PORTB=0x45; PORTB=PORTB>>2; C=C<<3; PORTB ^=C; (9 marks) d) Give the bit size, and the maximum and minimum ranges of the following data types used in C. i. char ii. unsigned int iii. long (6 marks)

6 Page 6 of 7 5. a) A stepper motor has an angular resolution of 7.5 degrees per step. If the clock input producing the stepper motor drive sequence is 100Hz, what will be the rotational speed of the stepper motor in revolutions per minute? b) One mode of operation to drive a stepper motor is called Half Stepping. Describe the operation of this mode of operation. Illustrate your answer with the aid of diagrams (9 marks) c) A circuit used to drive a load by a microcontroller using a transistor as a switch is shown in Figure 3. Using the parameters given calculate the required value of the resistor R. V+ uc R Load V+ = 12V Load resistance = 120 Ohms HFE of transistor is100 Microcontroller output is 5V for a logic High and0v for a logic low Figure 3 Transistor as a switch

7 6. a) What is the difference between combinational logic and sequential logic. b) Implement the following Boolean expression using standard logic gates. Z = (A. B) + (C ) + D (5 Marks) c) Generate a Boolean expression from the following logic diagram. d) Show the symbol for a positive edge triggered D type flip flop and a negative edge triggered D type flip flop, and describe its operation using a sample timing diagram. (7 marks) END OF QUESTIONS