Photo AI
Refer to FIGURE 2.2 and answer the questions that follow - NSC Electrical Technology Digital - Question 2 - 2020 - Paper 1
Question 2
Refer to FIGURE 2.2 and answer the questions that follow. 2.2.1 Identify the multivibrator in FIGURE 2.2. 2.2.2 Describe the operation of the multivibrator in FIGU... show full transcript
Worked Solution & Example Answer:Refer to FIGURE 2.2 and answer the questions that follow - NSC Electrical Technology Digital - Question 2 - 2020 - Paper 1
Step 1
Step 2
2.2.2 Describe the operation of the multivibrator in FIGURE 2.2 from a point where the capacitor has just discharged and point is low.
Answer
When the capacitor in the circuit has just discharged, it initially has a voltage of 0V across it. This causes the voltage at point A to be less than the reference voltage set by the voltage divider of resistors R1 and R2. As the capacitor begins to charge, the voltage at point A increases gradually until it reaches the upper threshold level.
Once the voltage at point A exceeds this threshold, the output of the op-amp switches from high to low, causing the capacitor to discharge again, creating a continuous oscillation between high and low states.
Step 3
2.2.3 Explain how the frequency of the multivibrator in FIGURE 2.2 can be increased.
Answer
The frequency of the astable multivibrator can be increased by decreasing the values of either the resistors R1 or R2, or by reducing the capacitance of the capacitor C1. This is due to the relationship between frequency (f), resistance (R), and capacitance (C) defined as:
By adjusting these components, the period (T) of the oscillation can be shortened, leading to an increase in frequency.