- Select frequency, inductance, or capacitance as the unknown.
- Choose a series or parallel circuit and calculation model.
- Enter known component values with their matching units.
- Add voltage, tolerances, losses, parasitics, source, and load values.
- Choose the frequency-response range, point count, and scale.
- Calculate, review the results, then export or print them.
| Application | Circuit | R | L | C | Approximate resonance |
|---|---|---|---|---|---|
| Audio filter | Series | 10 Ω | 10 mH | 1 µF | 1.592 kHz |
| Radio tuned circuit | Parallel | 100 kΩ | 100 µH | 100 pF | 1.592 MHz |
| Low-Q damped circuit | Series | 100 Ω | 25 mH | 2.2 µF | 678.6 Hz |
| High-Q tank circuit | Parallel | 1 MΩ | 47 µH | 220 pF | 1.565 MHz |
What resonance means
Resonance occurs when inductive and capacitive effects balance. Their opposite reactances cancel at the resonant frequency. Circuit resistance then controls damping and response sharpness.
Series and parallel resonance
A series RLC circuit reaches minimum impedance near resonance. Current therefore reaches its greatest value around that point. A parallel RLC tank reaches maximum impedance instead.
Quality factor and bandwidth
Quality factor describes resonance sharpness and stored energy. Higher Q normally produces a narrower response bandwidth. The cutoff frequencies define the half-power response limits.
Practical limitations
Real inductors and capacitors contain resistance and parasitics. These losses shift response and reduce achievable quality factor. Measurements may differ because component behavior changes with frequency.
Does resistance change ideal resonance frequency?
The basic ideal formula depends only on inductance and capacitance. Resistance mainly changes damping, bandwidth, current, and quality factor.
Why can practical resonance differ from ideal resonance?
Inductor winding resistance, capacitor ESR, leakage, source resistance, load resistance, and parasitic capacitance alter the complete impedance response.
What happens in a series RLC circuit at resonance?
Net reactance approaches zero, total impedance becomes smallest, and source current usually reaches its maximum value.
What happens in a parallel RLC circuit at resonance?
Inductive and capacitive branch currents oppose each other. Tank impedance becomes large while source current becomes comparatively small.
What is angular resonance frequency?
Angular frequency is measured in radians per second. It equals ordinary frequency multiplied by two times pi.
How are cutoff frequencies found?
This calculator searches the modeled response for points where the selected resonance response falls to its half-power level.
How do component tolerances affect resonance?
Higher inductance or capacitance lowers resonance. Lower values raise resonance, producing a predictable worst-case frequency range.
Can this calculator design an RLC circuit?
Yes. Select inductance or capacitance as the unknown, then enter the desired frequency and remaining known component.
Why are inductor and capacitor voltages high?
In a high-Q series circuit, reactive voltages can exceed supply voltage because energy repeatedly transfers between both components.
Should I use a linear or logarithmic frequency scale?
Use logarithmic scaling for wide frequency ranges. Use linear scaling for a narrow inspection around resonance.
Are these results suitable for final hardware certification?
No. Verify designs with component datasheets, circuit simulation, laboratory measurements, thermal limits, voltage ratings, and applicable engineering standards.