What is a Capacitor?
A capacitor stores energy in an electric field between two plates. Capacitance is measured in farads (F), typically µF, nF or pF. In student projects, capacitors smooth power supplies, filter noise, couple audio signals, and time RC circuits.
Types you'll encounter
- Ceramic (non-polarised, small values pF–µF)
- Electrolytic (polarised, large values µF–mF, watch the +/− marking)
- Tantalum (small, precise, polarised)
- Supercapacitor (huge, for backup power)
Where you'll use one
- 100 nF across VCC/GND of every IC ('decoupling') to reject noise
- 10 µF – 1000 µF on power rails to smooth ripple
- Timing element in 555 timer circuits
- Coupling capacitor between audio stages
FAQs
Does polarity matter?
Yes for electrolytic and tantalum. Reversing polarity can make them explode. Ceramic capacitors are non-polarised.
Why does my Arduino reset randomly?
Add a 100 µF electrolytic capacitor across VIN and GND — the supply is dipping when motors or Wi-Fi radios pull current.
