Capacitors

1 Definition

1.1 capacitor

A capacitor is a passive two-terminal electronic component that stores electrical energy in an electric field, created by a voltage difference between its plates.

capacitors

Capacitor symbol

Capacitor symbol

1.2 Capasitence

Capacitance is the ability of a substance or device to store an electrical charge.Commonly, capacitance is associated with capacitors.It is a measure of how much electric charge can be stored for a given voltage.

2. Features

  • Measurement: measured in farads (F), typically in microfarads (µF), nanofarads (nF), or picofarads (pF).
  • Voltage Rating: maximum voltage it can safely handle without breaking down.
  • Tolerance: how much the actual capacitance can vary from the stated value (e.g., ±5%, ±10%, ±20%).
  • Temperature Coefficient: capacitance changes with temperature.
  • Physical Size: larger capacitors often have higher capacitance or voltage ratings.
  • Fixed or Variable: can be fixed (most common) or adjustable (trimmer capacitors).

4. How to Use

Safety Note

Do not touch the terminals of a charged capacitor. Capacitors can store a dangerous electric charge even after power is disconnected, which may result in electric shock.

4.1. Identify the capacitor value

  • Read printed numbers (e.g., “104” = 100 nF) or use a capacitance meter.
  • Value is given in Farads (F) or its smaller units (µF, nF, pF).

capacitor value code

4.2. Choose the right capacitor

  • Capacitance value (for filtering, timing, or coupling needs).
  • Voltage rating (must be higher than the circuit voltage).
  • Type (electrolytic, ceramic, film, tantalum, etc.).

4.3. Connect it correctly

  • Polarity: electrolytic and tantalum capacitors are polarized (marked with + or –); ceramic capacitors are non-polarized.
  • In parallel: total capacitance is the sum of all capacitors. => increases overall capacitance.
  • In series: total capacitance is less than the smallest capacitor. => increases overall voltage handling, decreases capacitance.

4.4. Test and verify

  • Use a multimeter with capacitance mode to measure actual capacitance.
  • Check for leakage current in electrolytics.
  • Ensure the capacitor is not overheating or bulging.

4.5. Install in circuit

  • On breadboard: insert leads into holes.
  • On PCB: solder into the correct pads, respecting polarity.

5. When to use

  • Energy Storage: to store and release electrical energy quickly (e.g., camera flash).
  • Filtering: to smooth voltage in power supplies by reducing ripple.
  • Coupling/Decoupling: to block DC and allow AC signals in audio or communication circuits, or to stabilize voltage.
  • Timing Circuits: with resistors to set delays or oscillation frequencies.
  • Filtering in AC to DC Circuits: Capacitors smooth the pulsating DC output from a rectifier, making it closer to a steady DC voltage.

    6. Video Explanation

video coming soon