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⏲ 555 Timer Calculator

Astable oscillator and monostable one-shot pulse calculations with circuit diagrams

Astable Inputs

Frequency
—
Period
—
High Time (tH)
—
Low Time (tL)
—
Duty Cycle—

Astable Circuit

Vcc NE555 4 8 7 6 3 5 2 1 R₁ DIS R₂ THR C TRIG GND Output 10 nF
Vcc supply & RST tie
R1 (charge only)
R2 (charge & discharge)
Timing capacitor C
Output (square wave)
GND

📐 Formula Reference

Astable: tH = 0.693 × (R1 + R2) × C  |  tL = 0.693 × R2 × C

f = 1.44 / ((R1 + 2×R2) × C)  |  Duty = (R1 + R2) / (R1 + 2×R2)

Monostable: tw = 1.1 × R × C

R in Ω, C in Farads for exact results. Calculator handles unit conversion automatically.