Refer to FIGURE 2.1 below and answer the questions that follow - NSC Electrical Technology Digital - Question 2 - 2021 - Paper 1
Question 2
Refer to FIGURE 2.1 below and answer the questions that follow.
2.1 Identify the multivibrator in FIGURE 2.1.
2.2 State the polarity of the pulse provided on the ... show full transcript
Worked Solution & Example Answer:Refer to FIGURE 2.1 below and answer the questions that follow - NSC Electrical Technology Digital - Question 2 - 2021 - Paper 1
Step 1
Identify the multivibrator in FIGURE 2.1.
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Answer
The multivibrator in FIGURE 2.1 is a monostable multivibrator. This circuit produces a single output pulse in response to a trigger input.
Step 2
State the polarity of the pulse provided on the inverting input switch S5 is pressed.
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Answer
When switch S5 is pressed, the polarity of the pulse provided on the inverting input is negative. This is because the inverting input is connected to a lower potential which results in a negative pulse.
Step 3
State TWO functions of the 741 op-amp in the circuit.
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Answer
The 741 op-amp is used as a voltage comparator to compare the input voltage against a reference voltage.
It also functions as a signal amplifier by amplifying the difference between its inverting and non-inverting inputs.
Step 4
In which LED will be forward biased when S5 is pressed.
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Answer
When switch S5 is pressed, LED1 will be forward biased as the output of the op-amp switches high, allowing current to flow through LED1.
Step 5
State the polarity of the voltage present on pin 3 after switch S5 is pressed.
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Answer
After switch S5 is pressed, the polarity of the voltage present on pin 3 of the op-amp is positive. This occurs as the output goes high in response to the trigger from the inverting input.
