Design your oscillator circuit and visualize the output waveform in real-time.
When configured in astable mode, the 555 timer IC acts as an oscillator (a continuous square wave generator). It has no stable state—it continuously toggles its output between HIGH and LOW without requiring any external trigger. This makes it perfect for flashing LEDs, generating clock pulses for digital circuits, or creating basic synthesizer tones.
The characteristics of the output wave are completely controlled by the three external components you specify above: R1, R2, and C1.
t1 = 0.693 × (R1 + R2) × C1t2 = 0.693 × R2 × C1T = t1 + t2f = 1.44 / ((R1 + 2×R2) × C1)In a standard 555 astable circuit, the duty cycle (the percentage of time the signal is HIGH) will always be greater than 50%. This is because capacitor charging goes through R1 + R2, while discharging only goes through R2. If you need a duty cycle of exactly 50% or less, you typically need to add a signal diode in parallel with R2 to bypass it during the charging phase.