Physics

Capacitor Size Calculator

Find the smoothing capacitor needed for a power supply.

Load current (A)

Ripple period

Allowed ripple (V)

Calculated Output

Capacitance (µF) 10,000

Capacitance (F) 0.01

Formula: C = I·t ÷ ΔV

Step-by-Step Breakdown

1. Values used:

2. Load current = 1 A

3. Ripple period = 0.01

4. Allowed ripple = 1 V

6. Capacitance = 10,000µF

7. Capacitance = Load current x Ripple period = 1 x 0.01 = 0.01F

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The math behind it

C = I·t ÷ ΔV. More load current or tighter ripple needs a bigger capacitor.

1 A, 10 ms period, 1 V ripple → 10,000 µF.

What is the ripple period?

1/(2·mains frequency) for a full-wave rectifier — about 10 ms at 50 Hz.