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Q1— Section header —
1.1Various options are given as possible answ ers to the following questions. Choose the answer and write only the le tter (A C\ next to the question number (1.1.1
1.1.5\n the ANSWER BOOK.
1.1.1What is freq uency selectivity? The frequency at which the capacitive reactance equals the resistance in a low pass RC
1.1.2What is bandwidth? The frequency at which the capacitive reactance equals the resistance in a low pass RC
1.1.3What is cut off frequency? The frequency at which the capacitive reactance equals the resistance in a low
1.1.4What is reactive power in an RLC circuit? The upper and lower cu
1.1.5What is active power in an RLC circuit?
1.2The circuit below shows an inductor connected in series with a r esistor. he voltage across the inductor (V \is 40 V and the voltage across the resistor (V \0 V.
1.2.1Calculate the total voltage across the circuit. (3\
1.2.2Calculate t he phase angle between the total voltage and the total current. (3\
1.2.3Calculate the impedance of the circuit. (3\
1.2.4Draw the phasor diagram of the circuit. (6\ [20]20
Q2— Section header —
2.1Indicate whether the following statements ar e TRUE or FALSE. Choose the answer and write only 'True' or 'F al se' next to the question number (2.1.1
2.1.5\ the ANSWER BOOK.
2.1.1When the capacitor in an LC oscillator circuit is at maximum, the inductor energy is at minimum.
2.1.2In a n LC oscillator the frequency of the oscillator is proportional to L or C.
2.1.3With undamped oscillation, the amplitude of the oscillations remains constant.
2.1.4Hartley oscillator is commonly used in radio transmitters.
2.1.5
2.2Name FIVE factors that affect oscillation frequency. (5\ (12041024\ Copyright reserved
2.3Explain each of the following:
2.3.1mplifier
2.3.2
2.4Give TWO applications of each of the following multivibrators:
2.4.1Astable multivibrator
2.4.2Monostable multivibrator
2.4.3
2.5Give the meaning of each of the followin power supplier abbreviations:
2.5.1SMPS
2.5.2
2.6Study the circuit diagram below and answer the questions.
2.6.1Determine the saturation current (3\
2.6.2Determine the cut off voltage (1\
2.6.3Draw the DC load line from the above values. (4\ [30]30
Q3— Section header —
3.1Briefly explain the common problem experienced when using a strip board for the first time. (3\
3.2Name FOUR common faul ts in relays re sulting in a malfunctioning circuit. (4\
3.3Briefly explain each of the following parameter procedures to replace a transistor when using data sheet s:
3.3.1Maximum collector base voltage (V CBO
3.3.2Maximum collector emitter voltage (V CE
3.3.3Maximum emitter base voltage (V EBO
3.3.4Power dissipation (P in watts\
3.3.5
3.4Use the semicon ductor technical manual shown in the table below to find t he main characteristics of BC640 devices. (6\ Device
3.5What is an optocoupler (2\ [20] (12041024\20
Q4— Section header —
4.1Convert each of the following as indicated:
4.1.100110100 BCD to decimal (1\
4.1.20000 BCD to XS (1\
4.1.3510 to 2421BCD code (1\
4.2.1Make a neat labelled diagram of a four stage serial in serial out
4.2.2Explain the operation of the shift register in 4.2.1. (6\ [15]15
Q5— Section header —
5.2START STOP T