GCSE Electronics June 2003 Paper

For Examiner’s Use Number Number 123456789 Mark Mark Total (Column 1) Total (Column 2) TOTAL Examiner’s Initials General Certificate of Secondary Education Summer 2003 ELECTRONICS 3432/F Tuesday 3 June 2003 Afternoon Session In addition to this paper you will require: 􀁺 a pencil and a ruler; 􀁺 a calculator. Time allowed: 1 hour 30 minutes Instructions 􀁺 Use blue or black ink or a ball-point pen. 􀁺 Fill in the boxes at the top of this page. 􀁺 Answer all the questions in the spaces provided. 􀁺 Show the working of your calculations. Information 􀁺 The maximum mark for this paper is 120. 􀁺 Mark allocations 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 reminded of the need for good English and clear presentation in your answers. 0203/3432/F Surname Other Names Centre Number Candidate Number Candidate Signature FOUNDATION TIER Copyright © 2003 AQA and its licensors. All rights reserved.2 0203/3432/F Information Sheet The following information may be useful in answering the questions. 1. Power Power = voltage x current; P = VI 2. Amplifiers Voltage gain GV = VOUT VIN 3. Resistor colour code The colours in the resistor colour code correspond to the following values. BLACK 0 GREEN 5 BROWN 1 BLUE 6 RED 2 VIOLET 7 ORANGE 3 GREY 8 YELLOW 4 WHITE 9 The fourth band colour gives the tolerance. GOLD ±5% SILVER ±10% No fourth band ±20% 4. Resistor printed code (BS 1852) R means × 1 K means × 1000 M means × 1 000 000 Position of letter gives the decimal point. Tolerances are indicated by adding a letter at the end. J ± 5% K ± 10% M ± 20% e.g. 5K6J = 5.6 kΩ ± 5% 5. Preferred values for resistors (E24 SERIES) 1.0 1.1 1.2 1.3 1.5 1.6 1.8 2.0 2.2 2.4 2.7 3.0 3.3 3.6 3.9 4.3 4.7 5.1 5.6 6.2 6.8 7.5 8.2 9.1 and multiples of ten. 6. Resistance = voltage ; R =V current R = I 7. Effective resistance, R, of resistors in series is given by R = R1 + R2 + R3. 8. Effective resistance, R, of two resistors R1 and R2 in parallel is given by 1 = 1 + 1 R R1 R2 9. A.C. waveforms (a) Frequency of waveform = 1 ; f = 1 time period T (b) peak value = 1.4 x rms value 10. Astable and monostable generators using 555 timers (a) Monostable mode, time period T= 1.1 R1 x C1 (b) Astable mode, time period T= (R1 + 2R2) C1 1.44Answer all questions in the spaces provided. 1 The diagram shows the inside of a mains plug. (a) Label on the diagram above: the cord grip the fuse the live wire the earth wire. (4 marks) (b) What are the colours of: (i) the earth wire? ....................................................................................................................... (ii) the live wire? ......................................................................................................................... (iii) the neutral wire? .................................................................................................................... (3 marks) (c) Refer to the diagram above. (i) Which part of the wired plug is a safety hazard? .............................................................................................................................................. (ii) How can this be improved? .............................................................................................................................................. .............................................................................................................................................. (iii) What makes this wired plug unsuitable for a 25W soldering iron? .............................................................................................................................................. .............................................................................................................................................. (3 marks) 10 0203/3432/F LEAVE MARGIN BLANK Turn over􀀗 3 ................................................ ................................................ ................................................ ................................................ 13A2 Name each component symbol shown by completing the name column on every line. Tick one of the other columns for each component to show whether the component is an input device or an output device. (10 marks) 10 0203/3432/F LEAVE MARGIN BLANK 4 Symbol Name Input Output3 The diagram shows a digital thermometer system. It will measure the temperature and show the result on a 7-segment display. (a) Which block represents: (i) an input? ............................................................................................................................... (ii) an output? ............................................................................................................................. (iii) an analogue process? ............................................................................................................ (iv) a digital process? ................................................................................................................... (4 marks) (b) In which block could: (i) an op-amp be used? .............................................................................................................. (ii) a D-type flip-flop be used? .................................................................................................. (iii) a thermistor be used? ............................................................................................................ (3 marks) (c) Which block: (i) increases the size of the signal? ........................................................................................... (ii) contains LEDs? .................................................................................................................... (iii) is a simple memory? ............................................................................................................ (3 marks) 10 0203/3432/F LEAVE MARGIN BLANK Turn over􀀗 5 temperature sensor amplifier analogue to digital converter latch display4 (a) Label the three types of logic gate in the diagram below. (3 marks) (b) Complete the truth table below to describe the operation of the logic circuit in part (a).(6 marks) (c) The inputs A and B are connected to temperature sensors. Hot gives a logic 1 and cold gives a logic 0. A is at the top of a tank of liquid and B is at the bottom. Q is connected to a buzzer which sounds when a logic 1 is present. Put a tick under the tank which will sound the buzzer. ......................... ......................... ........................ (1 mark) 10 0203/3432/F LEAVE MARGIN BLANK 6 A B C D Q 0 0 0 1 1 0 1 1 whole tank cold hot cold whole tank hot A B B B A A AB C Q D..................................... ..................................... .....................................5 (a) Name and describe the function of the following types of component. (i) Name ............................................................. Function ........................................................ ....................................................................... (ii) Name ............................................................. Function ........................................................ ....................................................................... State its forward voltage drop ...................... (5 marks) (b) Name this component and complete the information below. Name .............................................................................................................................................. Value .............................................................................................................................................. Tolerance ........................................................................................................................................ (5 marks) 10 0203/3432/F LEAVE MARGIN BLANK Turn over􀀗 7 green blue orange silver6 A block diagram of a hi-fi system is shown below. (a) Name the unlabelled block by writing its function in the empty box above. (1 mark) (b) Which sub-system: (i) converts electrical signals into sound signals?...................................................................... (ii) can be used to record and playback?..................................................................................... (iii) converts signals above 150 kHz into audio signals? ............................................................. (3 marks) (c) The tuner could be made from the first three sub-systems of a simple radio receiver shown in the diagram below. Describe the function of: (i) the aerial, .............................................................................................................................. .............................................................................................................................................. (ii) the rf tuned circuit, ............................................................................................................... .............................................................................................................................................. (iii) the demodulator. ................................................................................................................... .............................................................................................................................................. (6 marks) 10 0203/3432/F LEAVE MARGIN BLANK 8 cassette deck CD player tuner loudspeakers aerial rf tuned circuit demodulator7 (a) Which electronic component can: (i) limit current in a circuit? ...................................................................................................... (ii) store charge? ......................................................................................................................... (2 marks) (b) State the unit of: (i) power, .................................................................................................................................. (ii) frequency. ............................................................................................................................. (2 marks) (c) The lamp in the circuit below has 6V across it and the current through it is 0.06 A. (i) State the current through the resistor R. .............................................................................................................................................. Calculate, showing your working and the correct units for : (ii) the voltage across the resistor R, .............................................................................................................................................. .............................................................................................................................................. (iii) the value of resistor R, .............................................................................................................................................. .............................................................................................................................................. (iv) the power dissipated by the resistor R. .............................................................................................................................................. .............................................................................................................................................. (6 marks) 10 0203/3432/F LEAVE MARGIN BLANK Turn over􀀗 9 R +9V 0V8 The flowchart describes the operation of a car alarm and immobiliser. Some of the flowchart symbols have been left out. (a) (i) Draw the correct flowchart symbols where they are missing on the diagram. (ii) Label on the flowchart: a decision box an input box a loop an output box a process box (10 marks) 0203/3432/F LEAVE MARGIN BLANK 10 start yes no no no yes yes input state of ignition switch input signal from remote control is valid signal present? is 30 s delay over? operate immobiliser flash sidelights and bleep twice flash sidelights and bleep once bring alarm system into operation is ignition on? start 30 s delay(b) Using the flowchart in part (a), describe the sequence of events that occur in the 60 seconds after the ignition has been switched off and the remote control is not used to operate the system. What purpose might be served by this sequence of events? ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ (5 marks) (c) Using the flowchart in part (a) as a guide, draw a new flowchart to describe the part of the alarm system that would detect anyone entering the car. The system should give a short delay before sounding an audible alarm and flashing lights. While the delay is operating it should be possible to switch the alarm system off using the remote control. (5 marks) 20 0203/3432/F LEAVE MARGIN BLANK Turn over􀀗 119 A student makes an electronic doorbell system for the front and back doors of a house. The system is designed to make a different sequence of sounds depending on which switch is pressed. People in the house would then know which door to open. Part of the system is an astable using a 555 timer IC which provides pulses to a 4017 counter IC. (a) Complete the diagram below to show how a 555 timer IC is connected as an astable. On the diagram, draw two resistors, two capacitors and wire links to complete it. (6 marks) (b) (i) The 4017 counter has ten decoded outputs. Describe what happens to the logic levels at these outputs as pulses are fed into its clock input. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. 0203/3432/F LEAVE MARGIN BLANK 12 Discharge Threshold TriggerGround Control Output Reset +Vs 5550203/3432/F LEAVE MARGIN BLANK Turn over􀀗 13 Clock clock input 4017 from astable 0 1 2 3 4 5 6 7 8 9 Decoded outputs 101 0 Q (ii) Logic gates are connected to some of the 4017 outputs as on the diagram below. Complete the timing diagram below to show the output from Q as pulses are fed into the clock input. (iii) The logic output Q controls a buzzer, describe the pattern of sound made when the system operates. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. QUESTION 9 CONTINUES ON THE NEXT PAGE Q(iv) To make a different pattern of sound from the buzzer a different logic system is needed. Draw a logic diagram to show how to make the following pattern of sound: short buzz, short gap, longer buzz, longer gap. A 4017 IC diagram has been drawn for you to add suitable logic gates. (12 marks) 0203/3432/F LEAVE MARGIN BLANK 14 Clock 4017 from astable 0 1 2 3 4 5 6 7 8 9 Decoded outputs(c) (i) Each output from the logic system in part (b) opposite must only be sent to the buzzer when the relevant doorbell is pressed. Complete the diagram below showing how the gates and sub-systems are connected. (ii) This system still has one problem in that pressing either switch for a short time may give no output at all. Explain why this is and suggest a way of solving this problem. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. (6 marks) (d) The electronic doorbell system operates from the mains supply using a transformer. Which component can: (i) rectify the transformer output?.............................................................................................. (ii) smooth the rectified output?.................................................................................................. (iii) stabilise the smoothed output? .............................................................................................. (iv) Draw below a labelled circuit diagram of a suitable rectified, smoothed, regulated power supply that would operate from the transformer secondary. Transformer (6 marks) 30 END OF QUESTIONS 0203/3432/F LEAVE MARGIN BLANK 15 sound pattern 1 sound pattern 2 buzzer front door switch back door switch