Figure 6 shows a type of NOT gate called a Schmitt Trigger - AQA - A-Level Physics - Question 4 - 2022 - Paper 8
Question 4
Figure 6 shows a type of NOT gate called a Schmitt Trigger. This is connected to a capacitor of capacitance C and a resistor of resistance R to make an oscillator ci... show full transcript
Worked Solution & Example Answer:Figure 6 shows a type of NOT gate called a Schmitt Trigger - AQA - A-Level Physics - Question 4 - 2022 - Paper 8
Step 1
Stage 1: Since Ve is LOW, the output is HIGH.
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The output voltage Vout is HIGH as long as Ve remains below the lower trigger voltage Vl. This state allows the capacitor to charge, causing Ve to rise.
Step 2
Stage 2: The capacitor now charges through the resistor, making Ve rise.
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As the capacitor charges, the voltage across it increases. This process continues until the voltage reaches the upper trigger voltage Vu.
Step 3
Stage 3: When Ve reaches a value of Vu, the output voltage Vout drops LOW.
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Once Ve surpasses Vu, the Schmitt Trigger changes state, dropping Vout to LOW. This causes the capacitor to start discharging.
Step 4
Stage 4: The capacitor now discharges through the resistor causing the value of Ve to fall.
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As the capacitor discharges, the voltage Ve decreases until it approaches the lower trigger voltage Vl.
Step 5
Stage 5: When Ve reaches a value of Vl, the output voltage Vout jumps HIGH.
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At this point, the cycle starts over. The output switches back to HIGH, and the capacitor begins charging again.
