Tiêu đề Industrial Electronics-2019_S1.pdf ✅

Page 2 of 5 This page is intentionally left blank
Page 3 of 5 Question 1 (a) Using the datasheet provided for the SN74LS76A Dual JK flip flop, answer the following questions: i) Discuss the setup and hold times for this device. ii) What is the propagation delay for each FF of this device in the worst case? iii) If one FF is used as a MOD-2 counter, what is the maximum frequency the device will operate if the propagation delay is the worst case? iv) How many of this device is required to make a MOD-60 counter? [13 marks] (b) A jet aircraft employs a system for monitoring the rpm, pressure, and temperature values of its engines using sensors that operate as follows: Figure Q1 shows the logic circuit that controls a cockpit warning light for certain combinations of engine conditions. Assume that a HIGH at output W activates the warning light. i) Determine what engine conditions will give a warning to the pilot? ii) Change this circuit to one using all NAND gates. [12 marks] Figure Q1: Logic circuit for the cockpit warning light system Temperature Sensor Pressure Sensor RPM Sensor
Page 4 of 5 Question 2 (a) Design a circuit to perform the EXCLUSIVE OR function using only NAND and NOR gates. Simplify the circuit so that you use the smallest possible number of NAND and NOR gates (and only use NAND and NOR gates). Show your Boolean calculation. Check the result using truth tables. [7 marks] (b) In the circuit of Figure Q2, inputs A, B, and C are all initially LOW. Output Y is supposed to go HIGH only when A, B, and C go HIGH in a certain sequence. i) Determine the sequence that will make Y go HIGH. ii) Explain why the START pulse is needed? iii) Modify this circuit to use D FFs. [6 marks] Figure Q2: A dual J-K Flip Flop logic circuit (c) A house has two lights to illuminate the stairs leading from the hall to the upstairs landing. The lights can be switched OFF and ON by either one of two switches, one in the hall and one in the landing. The lights are to be OFF when both switches are either ON or OFF together, and the lights are to be ON when one switch is ON and the other is OFF. i) Obtain the truth table of the system. ii) Obtain the sum of products (SOP) Boolean expression for the system. iii) Implement the system using AND, NOT and OR logic gates. iv) Implement the system using exactly ONE logic gate. [12 marks]