Woodlands Ring Prelim 2022

This document consists of 22 printed pages. WOODLANDS RING SECONDARY SCHOOL Name : _____________________________ Reg No. ________ Class : ____________ _______________________________________________________________________ EXAMINATION : PRELIMINARY EXAMINATION LEVEL : SECONDARY 4 EXPRESS DATE: 31 AUG 2022 SUBJECT : ELECTRONICS (6063) PAPER: 1 DURATION : 2 hours MAX MARKS: 100 SETTER(S) : Mr Ong Chee Lim Parent’s/Guardian’s Signature: ______________________________________________________________________ READ THESE INSTRUCTIONS FIRST Write your name, class and register number in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. You may use a calculator. Section A Answer all questions. Section B Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. The total number of marks for this paper is 100. 100

2 DATASHEET Resistor Colour Codes 1st Colour Band 1st Digit 2nd Colour Band 2nd Digit 3rd Colour Band Multiplier 4th Colour Band Tolerance Black 0 Black 0 Black 0 Gold ± 5% Brown 1 Brown 1 Brown 1 Red ± 2% Red 2 Red 2 Red 2 Orange 3 Orange 3 Orange 3 Yellow 4 Yellow 4 Yellow 4 Green 5 Green 5 Green 5 Blue 6 Blue 6 Blue 6 Violet 7 Violet 7 Violet 7 Grey 8 Grey 8 Silver 0.01 White 9 White 9 Gold 0.1 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 4.3 4.7 5.1 5.6 6.2 6.8 7.5 8.2 9.1 and multiples of ten.

3 Table on Boolean algebra Single variable theorems Laws of Complementation • 0 = 1 • 1 = 0 • A̿ = A AND Laws • A. 0 = 0 • A ∙ 1 = A • A ∙ A = A • A ∙ A = 0 OR Laws • A + 0 = A • A + 1 = 1 • A + A = A • A + A = 1 Multivariable theorems Commutative Laws • A + B = B + A • A ∙ B = B ∙ A Associative Laws • A + (B + C) = (A + B) + C = A + B + C • A ∙ (B ∙ C) = (A ∙ B) ∙ C = A ∙ B ∙ C Distributive Laws • A ∙ (B + C) = A ∙ B + A ∙ C ; • (A + B) ∙ (C + D) = A ∙ C + B ∙ C + A ∙ D + B ∙ D Absorptive Laws • A + A ∙ B = A • A ∙ (A + B) = A • A + A̅ ∙ B = A + B • A ∙ (A̅ + B) = A ∙ B DeMorgan’s Theorems • (A + B) = A ∙ B • (A ∙ B) = A + B

4 Section A Answer all questions in this section. 1 A heating lamp has seven subsystems to turn on the heat as shown in Fig. 1.1. Fig. 1.1 Write the name (s) of each subsystem in the heating lamp to the correct function(s) in Table 1.1. Table 1.1 Function of subsystem Name(s) of subsystem Input Output Logic Timer Analogue to digital converter Switch [6] 2 Fig. 2.1 shows a simple resistor circuit. Fig. 2.1 Calculate the total effective resistance of the circuit. ………….…………………………………………………………………………………………. [2]

5 3 (a) Draw the circuit symbol for a microphone. [1] (b) State the function of an input transducer. ………………………………………………………………………….…………………… [1] 4 Fig. 4.1 shows two electrolytic capacitors connected in parallel to smooth the output of a DC power supply. A resistor, Rout, is connected across the capacitors to discharge them when the power supply is switched off. Fig. 4.1 Calculate (a) the current, Iout, when the power supply is on, ………….………………………………………………………………………………… [2] (b) the total capacitance, CT, of the two capacitors. ………….………………………………………………………………………………… [2]

6 5 Fig. 5.1 shows a RC circuit with E = 12.0 V, R = 1.26 MΩ and C = 1.70 μF. Fig. 5.1 (a) Calculate the time constant of the RC circuit. ………….…………………………………………………………………………………… [2] (b) Find the maximum charge of the capacitor during charging. ………….…………………………………………………………………………………… [2] (c) When the switch is closed, how long does it take for the potential difference across the capacitor to reach 8 V? You must show your working clearly. ………….…………………………………………………………………………………… [2]

7 6 The output of 555 timer is connected to an oscilloscope and the following waveform is captured in Fig. 6.1. Fig. 6.1 (a) State the peak voltage of the waveform. ………….…………………………………………………………………………………… [1] (b) Determine the ‘on time’ of the waveform. ………….…………………………………………………………………………………… [1] (c) Determine the duty cycle of the waveform. ………….…………………………………………………………………………………… [2]

8 7 Fig. 7.1 shows an incomplete circuit diagram. Connect an SPST switch and a general -purpose diode to Fig. 7.1 such that the user can set the light to be dim or bright. Single pole single throw (SPST) General-purpose diode Table 7.1 Fig. 7.1 [3] 8 Choose the correct type of Bipolar Junction Transistor for the switching circuits A and B shown in Fig. 8.1. For each circuit, draw the transistor symbol inside the dotted circle and label its type on the dashed line. Circuit A Circuit B Fig. 8.1 [4]

9 9 Fig. 9.1 shows a combinational logic circuit. Fig. 9.1 (a) Fig. 9.2 shows a timing diagram of the circuit. Complete the timing diagram of the circuit for X, Y and Q. Fig. 9.2 [3] (b) Write in terms of input A, B and C, the Boolean expressions for X, Y and Q. X = ………………………………………………………………………………… Y = ………………………………………………………………………………… Q = ………………………………………………………………………………… [3]

10 10 Fig. 10.1 shows a circuit using AC input signal. Fig. 10.1 The reference voltage is at the non-inverting input of the voltage comparator. Fig. 10.2a shows an input waveform Vs applied at the inverting input. Fig. 10.2a Fig. 10.2b (a) Draw the reference voltage on Fig. 10.2a. Indicate its voltage value. [1] (b) Draw the voltage signal waveform at Vout on Fig. 10.2b. Indicate its voltage value and necessary signal/line trace from Fig. 10.2a. [2]