RC Circuit Calculator

Calculate time constant, characteristic frequency, and capacitor charging behavior for RC circuits

RC Circuit Parameters

Resistance value of the resistor

Capacitance value of the capacitor

RC Circuit Results

0.000e+0 s
Time Constant (τ = RC)
0.000e+0 Hz
Characteristic Frequency (f)
0.000e+0 Hz rad/s
Angular Frequency (ω)
0.000e+0 s
99.3% Charge Time (5τ)

Time Constant: τ = R × C = 0 Ω × 0.000e+0 F

Characteristic Frequency: f = 1 / (2π × R × C) = 1 / (2π × τ)

Example Calculation

Audio Low-Pass Filter

Application: Low-pass filter for audio processing

Resistance: 1.6 kΩ

Capacitance: 100 nF

Target cutoff: ~1 kHz for removing high-frequency noise

Calculation Results

τ = R × C = 1600 Ω × 100×10⁻⁹ F = 160 μs

f = 1 / (2π × RC) = 1 / (2π × 160×10⁻⁶) ≈ 995 Hz

Perfect for removing frequencies above 1 kHz

RC Circuit Applications

Low-Pass Filter

Blocks high frequencies, allows low frequencies

fc = 1/(2πRC)

High-Pass Filter

Blocks low frequencies, allows high frequencies

Same fc, different configuration

Timing Circuit

Controls charging/discharging rates

τ = RC

Charging Milestones

1τ (63.2%)1 time constant
2τ (86.5%)2 time constants
3τ (95.0%)3 time constants
4τ (98.2%)4 time constants
5τ (99.3%)Fully charged

RC Circuit Tips

Larger RC = slower charging, lower cutoff frequency

Time constant τ determines charging speed

Cutoff frequency is where output drops to 70.7%

Phase shift occurs around cutoff frequency

Use for signal conditioning and timing

Understanding RC Circuits

What is an RC Circuit?

An RC circuit is a fundamental electrical circuit consisting of a resistor (R) and capacitor (C) connected in series or parallel. The resistor controls current flow while the capacitor stores electrical energy, creating time-dependent behavior essential for filtering and timing applications.

Key Characteristics

  • Time constant τ = RC determines response speed
  • Exponential charging/discharging behavior
  • Frequency-dependent response (filtering)
  • Phase shift between input and output

Mathematical Relationships

Time Constant: τ = R × C

Cutoff Frequency: fc = 1 / (2π × R × C)

Charging Voltage: V(t) = V₀ × (1 - e^(-t/τ))

Discharging Voltage: V(t) = V₀ × e^(-t/τ)

Current: I(t) = (V₀/R) × e^(-t/τ)

Common Applications

  • Audio crossover networks and tone controls
  • Power supply filtering and smoothing
  • Timer circuits and delay generators
  • Coupling and decoupling in amplifiers
  • Signal conditioning and noise filtering