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Refer to FIGURE 2.2 below and answer the questions that follow - NSC Electrical Technology Digital - Question 2 - 2019 - Paper 1
Question 2
Refer to FIGURE 2.2 below and answer the questions that follow. 2.2.1 State the function of R1 and R2. 2.2.2 Describe what happens when the set switch, S1, is pres... show full transcript
Worked Solution & Example Answer:Refer to FIGURE 2.2 below and answer the questions that follow - NSC Electrical Technology Digital - Question 2 - 2019 - Paper 1
Step 1
2.2.1 State the function of R1 and R2.
Answer
The resistors R1 and R2 in the bistable multivibrator circuit serve as pull-up resistors. They set the threshold levels for the 555 timer by establishing the reference voltages necessary for the operation of the circuit. R1 connects pin 7 (discharge) to Vcc, while R2 connects pin 6 (threshold) to ground, effectively determining the time delay during the switching operation.
Step 2
2.2.2 Describe what happens when the set switch, S1, is pressed.
Answer
When the set switch S1 is pressed, it pulls pin 2 (trigger) of the 555 timer low. This causes the output pin (pin 3) to go high, turning on the LED. The pressing of the switch sets the state of the multivibrator to stable '1', and it will remain in this state until the reset switch is pressed or the power is cycled off.
Step 3
2.2.3 Explain why threshold pin 6 is connected directly to ground.
Answer
Threshold pin 6 is connected directly to ground to ensure that it receives a low voltage level that will help reset the timer. This connection allows the 555 timer to detect when the voltage at pin 6 drops below a certain threshold, effectively helping in determining when the output should switch back to a low state.