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The circuit of given figure shows a 555 Timer IC connected as an astable multivibrator. The value of the capacitor C is 10 nF. The values of the resistors RA and RB for a frequency of 10 kHz and a duty cycle of 0.75 for the output voltage waveform are
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- RA = 3.62 kΩ, RB = 3.62 kΩ
- RA = 3.62 kΩ, RB = 7.25 kΩ
- RA = 7.25 kΩ, RB = 3.62 kΩ
- RA = 7.25 kΩ, RB = 7.25 kΩ
Correct Option: C
Duty cycle, α = TON/T
∴ TON = αT = 0.75 T
= 0.75 × 10–4 = 75 µ sec.
As TON = 0.7C (RA + RB)
| ∴ | = RA + RB | |
| 0.7 × 10-8 |
⇒ RA + RB = 10.714 kΩ
and TOFF = 0.7C RB
| ∴ RB = | = 3.57 kΩ | |
| 0.7 × 10-8 |
∴ RA = 7.25 kΩ
