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2.1FIGURE 2 below is a DC machine. Identify the parts labeled A to F. Write only the answer next to the letter (A F\ in the ANSWER BOOK. FIGURE 2 (6 1\ (6\
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3.1The field system is the stationary part of a DC machine. State the functions of the following components that make up the field system:
3.1.1Field coils
3.1.2
3.2Bearings are used to support the rotating armature of a DC machine. Name TWO types of bearings used in DC machines. (2\
3.3Laminations are thin layers that are bound together. Why are the field poles and the armature cores of DC machines laminated? (2\
3.4There are two types of armature windings in a DC machine. State which winding is used in the case of a:
3.4.1Low voltage, high current application.
3.4.210
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4.1Explain how a load test is conducted on an electrical machine. (8\
4.2Polarity test are one of the test need to be done during electrical installation, explain the main purpose of doing a polarity test on electrical equipment or installations. (2\ [10] 808011510
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5.1Draw a neat, labelled circuit diagram of an SCR by using transistors only. (4\
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5.3State any TWO advantages of using silicon controlled rectifier (2\ [10]10
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6.1An operational amplifier (op amp\ is an integrated circuit containing a number of transistors and other components. A typical op amp is the 741.
6.1.1Name the TWO different types of the 741 operational amplifier. (2\
6.1.2Sketch a fully labelled circuit symbol for an operational amplifier. (5\
6.2Name any THREE main characteristic of operational amplifier. (3\ [10]10
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7.1FIGURE 3 below shows output waveforms as displayed on the oscilloscope screen. Define the THREE waves in terms of rectification. FIGURE 3 (3\
7.2As a technician, for what reason will you use an oscilloscope and not a digital multi meter? (4\
7.3If you do not plan to use a digital multi meter for a long time, how should you take care of it? (1\ FIGURE
7.4You have just purchased a new oscilloscope and want to use it. What must be done first before using it? (2\ [10]10
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8.1Logic gates form part of the building blocks of electronic memory circuitry such as flip flops. Explain what a flip
8.2Study the diagram below and then answer the questions that follow: FIGURE 4
8.2.1Name the flip flop that is represented by the diagram in FIGURE 4. (1\
8.2.2Complete a truth table and IEC symbol for the flip flop in QUESTION
8.2.1above. (7\ [10]10
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9.1Various options are given as possible answers to the following questions. Choose the correct answer and write only the letter (A D\ next to the question number (9.1.1
9.1.6\n the ANSWER BOOK.
9.1.1all inputs are HIGH. at least one input is HIGH. all inputs are LOW. at least one input is LOW.
9.1.2with an output that complements the input. INVERTER gate Comparator OR gate
9.1.3any one of its inputs is HIGH. NOT gate NOR gate OR gate AND gate
9.1.4for any case. OR gate NOT gate AND gate NAND gate
9.1.5LOW inputs and a LOW output. LOW inputs and a HIGH output. HIGH inputs and a HIGH output.
9.1.6If a signal passing through a gate is inhibited by sending a LOW into AND NOR OR NAND
9.2Draw the truth table for a THREE input NAND gate. (4\ [10] 808011510
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10.101001010,0110 . (16\
10.2011,11 . (8\
10.376,25 10 . (2\
10.4111.01 . (10\
10.510