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8 of 12 articles

555 Timer Astable Mode

Free running oscillator, frequency and duty cycle formulas.

Darshan N
Updated: 19 March 2026
4 min read

555 Astable Mode Quiz

Test your ability to calculate frequency and duty cycle in 555 timer astable configurations.

Question 1 of 3

Q1.In a standard 555 astable circuit with RA, RB, and C, the capacitor charges through RA + RB and discharges through RB only. The duty cycle D = T_high / T_total is: