Capacitors

A capacitor stores electric charge in the insulator between two conductors. Ceramic and film types have small values and are non-polarized; electrolytic, tantalum and supercapacitors have large values but are polarized. Capacitance, voltage, polarity and loss (ESR) decide the choice.

7 types3 groupsSymbol IEC

Non-polarized

104 (100 nF, 50 V)

Ceramic discSmall-value general-purpose filtering and decoupling, breadboard experiments

Code: 104 = 100 nF
Voltage: 50 V
Polarity: None

0805, 100 nF, X7R, 50 V

MLCC (multilayer ceramic)Decoupling, high-frequency filter, SMD boards

Capacitance: 100 nF
Package: 0805
Dielectric: X7R

2A104J (100 nF, 100 V, ±5%)

Film (polyester/polypropylene)Stable, low-loss value in timing, audio and filter circuits

Capacitance: 100 nF
Voltage: 100 V
Polarity: None

Adjustable (trimmer) capacitorFine-tuning frequency in radio and oscillator circuits

Range: ≈2–60 pF
Adjustment: Screwdriver
Polarity: None

Polarized

100 µF 25 V, 105 °C

Aluminum electrolyticHigh capacity on power supply line: ripple filtering, energy buffer

Capacitance: 100 µF
Voltage: 25 V
Polarity: Yes

10 µF 16 V teardrop type (code 106)

TantalumStable µF values in a small body, compact boards

Capacitance: 10 µF
Voltage: 16 V
Polarity: Yes

Energy storage

5.5 V 1 F coin type

SupercapacitorShort-term backup energy: clock, memory, brief outages

Capacitance: 1 F
Voltage: 5.5 V (2 cells)
Polarity: Yes

Which one should I choose?

If you will put 100 nF at the chip’s supply pin

MLCC (multilayer ceramic)

Small, cheap and with very low ESR.

If you need a small general-purpose value on a breadboard

Ceramic disc

Leaded, nonpolar and easy to find.

For µF-level capacity on a power supply line

Aluminum electrolytic

It gives the cheapest large capacitance.

If you want a stable value in 555 or audio circuits

Film (polyester/polypropylene)

Its value changes little with temperature and voltage.

If you want a clock or memory to keep running briefly when power is cut

Supercapacitor

Farads of capacitance, fast charging.

If you'll fine-tune a radio or oscillator frequency

Adjustable (trimmer) capacitor

pF level, adjusted with a screwdriver.

Compare7 types · 6 features

Type	Capacitance range	Voltage	Polarity	Loss/ESR	Price	Typical use
Ceramic disc	1 pF – 100 nF	50 V typical	None	Low	Very low	Noise filtering
MLCC (multilayer ceramic)	1 pF – 100 µF	6.3–100 V	None	Very low	Very low	Decoupling
Aluminum electrolytic	1 µF – 10 000 µF	6.3–450 V	Yes	High	Low	Power supply filter
Tantalum	0.1–470 µF	4–50 V	Yes	Low-medium	Medium	Filter in a small area
Film (polyester/polypropylene)	1 nF – 10 µF	63–630 V	None	Very low	Medium	Timing, audio
Supercapacitor	0.1 F – 500 F	2.5–2.7 V / cell	Yes	Varies by type	Medium	Backup energy
Adjustable (trimmer) capacitor	≈2–60 pF	Low	None	Low	Medium	Fine frequency tuning

Typical values; vary by manufacturer and series.