Exam-style question
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Describe how the duty cycle of an astable multivibrator can be adjusted and explain the effect on the output pulse width.
Model answer
What a good answer should say
- The duty cycle can be changed by varying the ratio of the two resistors that control the charging and discharging times of the capacitor.
- Increasing the resistor that charges the capacitor relative to the discharge resistor lengthens the high pulse, raising the duty cycle.
- Conversely, decreasing that resistor shortens the high pulse and lowers the duty cycle.
- The pulse width of the output is directly proportional to the time the capacitor spends above the threshold voltage.
Explanation
Why this works
This answer shows analysis of how component values influence pulse width and duty cycle, testing the ability to link component variation to output characteristics.
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