Exam-style question
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If you want to increase the period of an astable 555 timer circuit without changing the duty cycle, which component should you adjust?.
- A.R1
- B.R2
- C.C
- D.All of the above
Model answer
What a good answer should say
- C
Explanation
Why this works
Formula: T = 0.693 (R1+2R2) C. Substitution: T ∝ C.
Working: Increasing C increases the period proportionally while the ratio (R1+R2)/(R1+2R2) – the duty cycle – remains unchanged. Answer: C.
Units: None. Conclusion: Changing the capacitor changes the period without affecting the duty cycle.
Common mistake
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