555 Timer Calculator

555 timer integrated circuits (ICs) are typically configured to produce a square waveform output. These common 555 timer IC circuits can be configured in either monostable or astable mode:

• Monostable mode: This configuration produces a short, single high pulse output, generated for a single input event (one-shot mode). The duration of this is determined by the circuit’s capacitance and resistance values
• Astable mode: This configuration produces a continuous square wave output (free-running mode). Both the high and low times and the frequency are determined by the circuit’s capacitance and resistance values.

The 555 timer calculator enables you to determine the output pulse frequency or duration based on the circuit’s capacitance and resistance values.

For monostable mode, the following 555 timer formula can be used:

T = 1.1RC

In other words, the output signal duration can be described as:

Time in Seconds (T) equal to the constant of 1.1, multiplied by the Resistance (R), multiplied by the Capacitance (C).

The following formulas can be used for astable mode:

Time high formula:

Tₕ = 0.693(R₁ + R₂)C

Time low formula:

Tₗ = 0.693R₂C

Frequency formula:

f = 1.44/((R₁ + 2R₂)C)