GCSE Electronics June 2006 Paper

For this paper you must have: ! a pencil and ruler ! a calculator General Certificate of Secondary Education June 2006 ELECTRONICS 3432/F Written Paper Foundation Tier Thursday 25 May 2006 1.30 pm to 3.00pm Time allowed: 1 hour 30 minutes Instructions ! Use blue or black ink or ball-point pen. ! Fill in the boxes at the top of this page. ! Answer all questions. ! Answer the questions in the spaces provided. ! Show the working of your calculations. Information ! The maximum mark for this paper is 120. ! The marks for questions are shown in brackets. ! A list of formulae and other information, which you may wish to use in your answers, is provided on page 2. ! You are expected to use a calculator where appropriate. ! You are reminded of the need for good English and clear presentation in your answers. M/Jun06/3432/F F 3432/F Leave blank Surname Other Names Centre Number Candidate Number Candidate Signature For Examiners Use Number Mark Number Mark 1 9 2345678 Total (Column 1) Total (Column 2) TOTAL Examiners Initials2 M/Jun06/3432/FTurn over! 3 LEAVE MARGIN BLANK M/Jun06/3432/F Answer all questions in the spaces provided. 1 A student goes into an electronics workshop alone after school to repair an electronic circuit. The workbench and the circuit are shown below. (a) State five dangers in this situation. 1 ......................................................................................................................................... 2 ......................................................................................................................................... 3 ......................................................................................................................................... 4 ......................................................................................................................................... 5 ......................................................................................................................................... (5 marks) (b) The student touches the live wire of the mains supply. State two different effects this will have on the student. 1 ......................................................................................................................................... 2 ......................................................................................................................................... (2 marks) (c) You discover the student after this has happened. Give three steps you would take to help the student. 1 ......................................................................................................................................... 2 ......................................................................................................................................... 3 ......................................................................................................................................... (3 marks) ____ 104 LEAVE MARGIN BLANK M/Jun06/3432/F 2 (a) Name the circuit symbols shown below. (5 marks) (b) Complete the following sentences about transducers. (i) An output transducer that converts electrical energy into sound energy is a .................................. . (ii) An input transducer that converts sound energy into electrical energy is a .................................. . (iii) An LED is an .................................. transducer that converts .................................. energy into .................................. energy. (5 marks) Symbol Name ____ 10Turn over! 5 LEAVE MARGIN BLANK M/Jun06/3432/F 3 A block diagram of an electronic temperature control system is shown below. (a) Which block represents (i) an input, ..................................................................................................................... (ii) an output, ................................................................................................................... (iii) an analogue to digital converter? .............................................................................. (3 marks) (b) In which block could (i) an op-amp be found, ... (ii) a thermistor be found? (2 marks) (c) Which two blocks use a small current to control a larger current? 1 ................................................................................................................................... 2 ................................................................................................................................... (2 marks) (d) Describe three actions of this system when the temperature drops below the set level. 1 ......................................................................................................................................... 2 ......................................................................................................................................... 3 ......................................................................................................................................... (3 marks) temperature sensor comparator transistor switch electromagnetic switch heater ____ 106 LEAVE MARGIN BLANK M/Jun06/3432/F 4 (a) Label the three different types of logic gate in the circuit below. (3 marks) (b) Complete the truth table below to describe the operation of the logic circuit. (4 marks) (c) Logic input A is connected to a door switch that gives logic 0 when open and logic 1 when closed. Logic input B is connected to a heat sensor that gives logic 0 when cold and logic 1 when warm. Describe the two sets of conditions that would cause Q to give logic 1. 1 ................................................................. and .......................................................... 2 ................................................................ and ............................................................ (2 marks) (d) How could the circuit be changed so that the logic values of the output Q are reversed? ............................................................................................................................................ (1 mark) ...................................................... ...................................................... ................................ A C Q D B A B C D Q 0 0 0 1 1 0 1 1 ____ 10Turn over! 7 LEAVE MARGIN BLANK M/Jun06/3432/F +6V 0V 5 A 555 timer IC is used to make an astable. (a) Complete the circuit diagram of the astable below. Add wire links, draw and label the timing resistor R2 and the timing capacitor C. (6 marks) (b) The astable above operates on a supply voltage of 6V. Draw on the axes below a typical output signal from this circuit. (4 marks) ____ 10 555 IC 06 12 time/s output /V R1 reset +Vs discharge threshold trigger ground control voltage output8 LEAVE MARGIN BLANK M/Jun06/3432/F 6 A block diagram of a simple radio receiver system is shown below. (a) Complete these sentences to describe the function of each of the following sub-systems. (i) The aerial converts..................................................................................................... into .......................................................................................................................... . (ii) The tuned circuit ....................................................................................................... ................................................................................................................................ . (iii) The demodulator converts ........................................................................................ into ......................................................................................................................... . (6 marks) (b) The audio frequency amplifier can be made using an audio amplifier IC. What does this type of IC do to the audio frequency signal? Choose from: decreases does not change increases Select from the list above and use your answer to complete the sentences which follow. You may use each answer once, more than once, or not at all. (i) The signal voltage................................................................................................... . (ii) The signal current .................................................................................................. . (iii) The signal frequency............................................................................................... . (iv) The signal power .................................................................................................... . (4 marks) aerial tuned circuit demodulator af amplifier loudspeaker ____ 10Turn over! 9 LEAVE MARGIN BLANK M/Jun06/3432/F 7 A MOSFET is used to switch current to an electric motor. (a) Label the leads of the MOSFET on the circuit diagram below. (3 marks) (b) Another component is required to protect the MOSFET when the motor switches off. Draw this component, in the correct location, on to the diagram above. (3 marks) (c) Give a reason why an input resistor is not needed in this circuit. ............................................................................................................................................ (1 mark) (d) The motor current is 10 A. Why is a MOSFET a better choice for the switching function than a bipolar transistor? ............................................................................................................................................ (1 mark) (e) For which of the following input voltages will the motor be: Choose from: 0V, 1V, 2V, 3V or 5V (i) completely off, ............................................... (ii) fully on? ......................................................... (2 marks) +Vs 0V input M ..................................... ..................................... ..................................... ____ 1010 LEAVE MARGIN BLANK M/Jun06/3432/F 8 The diagram below shows a bent wire game, where a contestant tries to pass a metal ring over a bent wire track without touching it. The flowchart describes what happens when the ring touches the wire for the first, second, and third time. Each time the ring touches the wire, a 1 second pulse is produced and the number of touches is shown by three green LEDs. (a) Draw the correct flowchart symbols at five places where they are missing above. (5 marks) (b) Label on the flowchart: a decision box, an input box, a loop, an output box and a process box (5 marks) switch game on input signal from ring count pulses is count =1? produce 1 sec pulse N Y NN Y Y start is count =2? is count =3? Light 1st LED Light 2nd LED Light 3rd LEDTurn over! 11 LEAVE MARGIN BLANK M/Jun06/3432/F (c) The action of the bent wire game continues after the third touch. The fourth touch makes a yellow LED flash on and off as a warning sign that the contestant has no more chances. The fifth touch makes a red LED flash on and off and a buzzer sound to mark the end of the game. Draw a flowchart for this part of the game, to follow on from the flowchart on page 10. Use that flowchart to help you. The lower part of that flowchart is drawn here; start your flowchart from it. (10 marks) N Y is count =3? ____ 2012 LEAVE MARGIN BLANK M/Jun06/3432/F 9 A student decides to construct a bent wire game similar to that described in Question 8. It is not necessary to have completed your answer to Question 8 before attempting this question. The bent wire and the ring form the input sub-system which triggers a 555 IC monostable circuit when the ring touches the wire. A 4017 counter IC counts the pulses from the monostable and provides outputs to switch the LEDs, and also a buzzer which sounds only when the ring touches the wire for a fifth time. (a) Draw a system block diagram to show how all the sub-systems should be connected. (5 marks) (b) Complete the circuit diagram below to show how the 555 IC should be connected to form the monostable. Include a timing resistor and capacitor, any other components needed and label the connection that goes to the counter. (8 marks) +6V 0V +Vs reset output ground control voltage discharge threshold trigger pull up resistor from ring from wire 555 ICTurn over! 13 LEAVE MARGIN BLANK M/Jun06/3432/F (c) (i) Complete the timing diagram below to show the output voltage from the monostable during the time interval shown. The monostable has a period of 1 second. (ii) What component in the monostable circuit keeps the trigger voltage high when the ring is not touching the wire? ................................................................................................................................... (iii) What action forces the trigger voltage to go low? ................................................................................................................................... (6 marks) (d) Add to the counter circuit diagram below three LEDs and their series resistors that would indicate the first three pulses from the monostable. (6 marks) Question 9 continues on the next page 0 1 2 3 4 ring voltage /V monostable output voltage /V time/s 0 1 2 3 4 5 6 7 8 9 4017 input +Vs 0V14 LEAVE MARGIN BLANK M/Jun06/3432/F (e) What extra sub-system is required to make an LED flash on and off? ............................................................................................................................................ (1 mark) (f) The 4017 IC can supply a current of 10mA to each output, and is connected to a 9V battery. The LEDs have a forward voltage of 2V. (i) Calculate the voltage drop across the LED current limiting resistor. ................................................................................................................................... (ii) Calculate the required resistance of the LED current limiting resistor. ................................................................................................................................... (iii) State which resistor from the E24 range would be suitable if the current limit is not to be exceeded. ................................................................................................................................... (4 marks) END OF QUESTIONS ____ 3015 M/Jun06/3432/F There are no questions printed on this page16 M/Jun06/3432/F There are no questions printed on this page Copyright © 2006 AQA and its licensors. 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