555 Timer Calculator
Astable frequency / duty cycle, or monostable pulse width.
Values
Result
f = 655 Hz · duty 52.4% · thigh 0.9 ms · tlow 0.8 ms
The 555 timer
In astable mode the 555 oscillates: f = 1.44 / ((R1 + 2·R2)·C), with thigh = 0.693·(R1+R2)·C and tlow = 0.693·R2·C. Duty cycle is always >50% in the classic two-resistor circuit (use R1 ≪ R2 to approach 50%).
In monostable mode a trigger pulse produces one output pulse: t = 1.1·R·C.