A capacitor reduces ripple after rectification.
A reservoir capacitor charges at peaks and supplies the load between them. Ripple ΔV≈I_load/(f_ripple·C). More capacitance or a regulator reduces ripple. RC and LC filters further smooth. Large capacitors cause high inrush current.
100 mA with 100 Hz ripple frequency and 1000 µF gives about 1 V ripple.
A smoothing capacitor reduces ripple from a rectifier, which decides how clean a power rail is for sensitive electronics.
A capacitor reduces ripple after rectification.
A smoothing capacitor reduces ripple from a rectifier, which decides how clean a power rail is for sensitive electronics.
For a simple full-wave rectifier, the peak-to-peak ripple is roughly the load current divided by the product of frequency and capacitance.
It increases inrush current at switch-on and can increase cost and size, so the value must be balanced against these effects.
Typical applications include sizing the reservoir capacitor for a 5 V supply that must hold ripple below 50 mV, adding bulk capacitance to a motor controller supply and choosing the capacitor for a low-noise sensor power rail.
Study "Rectifier circuits" first (topic 5 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
Choose C by acceptable ripple. Electrolytics have ESR. Active regulators reject ripple.
100 mA with 100 Hz ripple frequency and 1000 µF gives about 1 V ripple.
The next topic is "Zener diode regulators", which builds directly on this one.
It is classed as Beginner in Electronics & Embedded (topic 6 of 104). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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