Introduction
In this article, we will discuss what capacitance is, what capacitors are and the different types of capacitors. This is part of several articles that will tackle basic electronics concepts and components.
What is Capacitance?
According to Wikipedia, Capacitance is the ratio of the amount of electric charge stored on a conductor to a difference in electric potential. For people who do not have any background in electronics, this is a complex definition. So let us explain it a little simpler. Capacitance is the measurement of a component, usually a capacitor, to hold a charge.
What are Capacitors?
Capacitors are electronic components that can hold a charge. The part of the capacitor that has this ability is made up of two conductive plates and a “dielectric” material. A dielectric material is a poor conductor but can be polarized when exposed to a magnetic field.
The ability of a capacitor to hold a charge is measured in “Farad”. This unit of capacitance was named after Michael Faraday, an English scientist who contributed to the study of electromagnetism and electrochemistry.
Types of Capacitors
- Electrolytic Capacitor – These capacitors have polarities. Meaning, their terminals are marked as either positive (+) or negative (-). Their values and voltage rating are clearly marked on the side.
- Mica Capacitor – These capacitors use silver mica as the dielectric material and are very small in size. These types are most resistant to mechanical, and temperature variations. Because of their small size, the values are written based on the capacitor code table. More on this later.
- Paper Capacitor – As the name implies, this type of capacitor uses oil paper or thinly waxed paper as its dielectric material. Paper capacitors have voltage ratings of up to 2,000 Volts.
- Film Capacitor – These capacitors use thin plastic sheets as the dielectric material. These types of capacitors are stable and low cost to manufacture.
- Non-Polarized Capacitor – these are basically two electrolytic capacitors connected in series and back-to-back (one of the like terminals are connected together).
- Ceramic Capacitor – These use ceramic discs as a dielectric material. These types of capacitors are used for their high-frequency response.
How to read capacitor codes
Capacitor values cannot be written directly to capacitors with small bodies. To solve this, manufacturers follow a Capacitor code table.
| Picofarad (pF) | Nanofarad (nF) | Microfarad (uF) | Code | Picofarad (pF) | Nanofarad (nF) | Microfarad (uF) | Code |
|---|---|---|---|---|---|---|---|
| 10 | 0.01 | 0.00001 | 100 | 4700 | 4.7 | 0.0047 | 472 |
| 15 | 0.015 | 0.000015 | 150 | 5000 | 5.0 | 0.005 | 502 |
| 22 | 0.022 | 0.000022 | 220 | 5600 | 5.6 | 0.0056 | 562 |
| 33 | 0.033 | 0.000033 | 330 | 6800 | 6.8 | 0.0068 | 682 |
| 47 | 0.047 | 0.000047 | 470 | 10000 | 10 | 0.01 | 103 |
| 100 | 0.1 | 0.0001 | 101 | 15000 | 15 | 0.015 | 153 |
| 120 | 0.12 | 0.00012 | 121 | 22000 | 22 | 0.22 | 223 |
| 130 | 0.13 | 0.00013 | 131 | 33000 | 33 | 0.033 | 333 |
| 150 | 0.15 | 0.00015 | 151 | 47000 | 47 | 0.047 | 473 |
| 180 | 0.18 | 0.00018 | 181 | 68000 | 68 | 0.068 | 683 |
| 220 | 0.22 | 0.00022 | 221 | 100000 | 100 | 0.1 | 104 |
| 330 | 0.33 | 0.00033 | 331 | 150000 | 150 | 0.15 | 154 |
| 470 | 0.47 | 0.00047 | 471 | 200000 | 200 | 0.2 | 254 |
| 560 | 0.56 | 0.00056 | 561 | 220000 | 220 | 0.22 | 224 |
| 680 | 0.68 | 0.00068 | 681 | 330000 | 330 | 0.33 | 334 |
| 750 | 0.75 | 0.00075 | 751 | 470000 | 470 | 0.47 | 474 |
| 820 | 0.82 | 0.00082 | 821 | 680000 | 680 | 0.68 | 684 |
| 1000 | 1.0 | 0.001 | 102 | 1000000 | 1000 | 1.0 | 105 |
| 1500 | 1.5 | 0.0015 | 152 | 1500000 | 1500 | 1.5 | 155 |
| 2000 | 2.0 | 0.002 | 202 | 2000000 | 2000 | 2.0 | 205 |
| 2200 | 2.2 | 0.022 | 222 | 2200000 | 2200 | 2.2 | 225 |
| 3300 | 3.3 | 0.0033 | 332 | 3300000 | 3300 | 3.3 | 335 |
Reading from left to right, the first two numbers are the first two digits of the value of the capacitor. The third number is the number of zeroes following the first two digits. The unit is in picoFarads (pF). For example, if the code is “332”, this means that the capacitor value is “33” followed by two zeroes which result in 3300 pF.
Conclusion
We hope this article has helped you understand what capacitance is, how capacitors work and how to read capacitor codes.
