What is the 555 astable frequency formula?

f = 1.44 / ((R1 + 2·R2) × C), with the high and low times set by R1, R2 and C.

Can a 555 produce a 50% duty cycle?

The standard astable output is always above 50%. Add a diode across R2 (or use a different topology) to reach close to 50%.

t = 1.1 × R × C — a single pulse of that length each time the timer is triggered.

555 타이머 계산기을(를) 위한 무료 온라인 도구입니다. 입력값은 기기 안에서 계산됩니다.

Mode

R1 (Ω)

R2 (Ω)

Unit

Choose astable (oscillator) or monostable (one-shot).
Enter R1, R2 (astable) or R (monostable) and C with its unit.
Click Calculate for frequency, period and duty cycle, or the output pulse width.

Astable mode (continuous square wave):

f = 1.44 / ((R1 + 2·R2) · C)

t_high = 0.693 · (R1 + R2) · C | t_low = 0.693 · R2 · C

Duty cycle = (R1 + R2) / (R1 + 2·R2). The standard 555 astable output is always above 50% duty; add a diode across R2 to get close to 50%.

Monostable mode (single pulse on trigger):

t = 1.1 · R · C

What is the 555 astable frequency formula?: f = 1.44 / ((R1 + 2·R2) × C), with the high and low times set by R1, R2 and C.
Can a 555 produce a 50% duty cycle?: The standard astable output is always above 50%. Add a diode across R2 (or use a different topology) to reach close to 50%.
What is the monostable pulse width?: t = 1.1 × R × C — a single pulse of that length each time the timer is triggered.