Calculate frequency, duty cycle, and pulse times for an NE555 timer in astable mode.
Component Values
kΩ
kΩ
µF
Calculation Results
Enter parameters to calculate
Quick Reference
fFrequency
t1High time = 0.693 * (R1 + R2) * C
t2Low time = 0.693 * R2 * C
Duty Cycle(t1 / (t1 + t2)) * 100
Overview
In astable mode, the NE555 timer acts as an oscillator, producing a continuous square wave. The frequency and duty cycle are determined by two resistors (R1, R2) and one capacitor (C).
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Pro Tips
R1 should be at least 1kΩ to prevent excessive current.
Total resistance (R1 + R2) should not exceed 10MΩ.
The duty cycle in this standard configuration is always greater than 50%.
Use high-quality capacitors (like film or C0G ceramic) for stable frequency.
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Fun Facts
"The 555 timer was designed by Hans Camenzind in 1971 and is still one of the most popular integrated circuits ever made."
"The name '555' comes from the three 5kΩ resistors used in its internal voltage divider network."
"Over 1 billion 555 timers are manufactured every year."
