Capacitors are often referred to as condensers which are devices for storing electrical charges. The ability of a capacitor to store a charge is called capacitance (C). And has a unit of Farad (F).
How Capacitors or Condensers Work
Capacitor Charge Formula
Capacitive Reactance Formula
Basically, capacitors are made (formed) from 2 insulated (separated) conductor plates from each other. The insulator or separator is called a dielectric. And based on the types of dielectrics, capacitors can be divided into several types, including:
- Ceramic condenser
- Electrolytic capacitor
- Capacitor mica
- Capacitor mylar
- Polyster capacitor
- Air condenser
Properties of Capacitors
- As a coupling, it holds DC current and passes AC current.
- As a filter, it stores DC current and when it is full it will be released.
Capacitors are divided into two groups, namely non-polar and polar.
1. Non-Polar Capacitors
It has no poles, its capacitance is below 1µF, made of wax paper, polythene, polyester and others.
Symbols for fixed (a) and variable (b) non-polar capacitors
One example of a non-electrolyte capacitor is a ceramic capacitor. This capacitor has a capacitance below 1 microfarad. Its two legs do not have positive and negative poles, so you don't need to worry about installing it upside down. This capacitor is usually used in intermediate frequency amplifier circuits.
2. Polar Capacitors
Has positive and negative terminals, capacitance ?1 µF, made of aluminum, tantalum.
Polar Capacitor or Elco (Electrolytic Condenser) Symbol
Electrolytic Capacitor (Elco) dielectric material is made of aluminum salt. This capacitor has a fairly large capacitance, above 1 micro farad. Elco has 2 legs that are positive and negative, so the installation should not be reversed.
Elco is usually used in low frequency amplifier circuits, as a DC current filter in the power supply. On the body of the elco is written the capacitance value and the positive and negative pole marks.
Damage that often occurs to Elco:
- Mica, ceramic, paper, and variable capacitors are connected between their legs. These capacitors can no longer be used, except for metal variable capacitors.
- Elcos often dry out, leak or explode due to incorrect polarity installation, or exceeding the working voltage limit of the capacitor.
- The capacitor capacity often changes and its legs often break.
- Dry (capacity changes)
- Short Circuit
- Explosion, which is caused by an error in providing positive and negative voltage, if the maximum voltage limit is exceeded it can also explode.
Series Connection in Capacitors
Parallel Capacitor Connection
Function of Capacitor
- Together the coil generates a certain frequency.
- Coupling one circuit with the next circuit.
- As Feedback, it returns the amplification results from the transistor to obtain greater amplification (feedback).
- As a bypass, it diverts AC current to the chassis/ground to get low tones (bass) on the amplifier.
- As a filter, to filter the AC current that still enters through the diode, so that it can be returned or rectified again.
How Capacitors Work
Charging and Discharging Capacitors
Network and graphics of charging (a) and discharging (b)
Capacitor Capacity
The capacitor capacity is measured in farads. The size of farads in practice is too large so it is usually expressed in smaller sizes, namely micro farads (µF or Mfd), pico farads (pF), nano farads (nF), and kilo farads (kF) see the equation below:
Stairs 1
- 1 farad = 1,000,000 Mfd
- 1 Mfd = 1.000.000 pF = 1.000 kF
- 1 kF = 1.000 pF = 1 nF
- 1 kpF = 1,000 pF = 0.001 µF = .001 µF
- 10 kpF = 10,000 pF = 0.01 µF = .01 µF
- 100 kpF = 100,000 pF =0.1 µF = .1 µF
Stairs 2
- 1 Farad = 1,000,000 µF (micro Farad)
- 1 µF = 1,000,000 pF (pico Farad)
- 1 µF = 1.000 nF (nano Farad)
- 1 nF = 1.000 pF (piko Farad)
- 1 pF = 1,000 µµF (micro-micro Farads)
Checking Mica / Ceramic Capacitors
- Connect the ohm meter to the capacitor.
- If the needle moves, it means the capacitor is good.
- If the needle moves to the right, it means the capacitor is connected between the legs.
- If the needle does not move, it means the capacitor is broken/damaged.
3. How to read capacitor values
a. Numeric Code
- Written 103, means the capacitance value = 10,000 pF = 10kF
- Written 102, means the capacitance value = 1000 pF = 1 kF
- So the last number is the number of zeros.
b. Color Code
Almost the same as the resistor, the difference is the first and second colors are numbers, the third color is the number of zeros, the fourth color is tolerance, and the fifth color is the maximum working voltage. The first color is the color furthest from the capacitor leg.
| Warna | Arti Warna Ke: | | | | |
|---------|----------------|---|-------|-----|------|
| | 1 | 2 | 3 | 4 | 5 |
| Hitam | 0 | 0 | - | 20% | - |
| Coklat | 1 | 1 | 0 | | 100V |
| Merah | 2 | 2 | 00 | | 250V |
| Jingga | 3 | 3 | 000 | | - |
| Kuning | 4 | 4 | 0000 | | 400V |
| Hijau | 5 | 5 | 00000 | | - |
| Biru | 6 | 6 | - | | 630V |
| Ungu | 7 | 7 | - | | - |
| Abu-Abu | 8 | 8 | - | | - |
| Putih | 9 | 9 | - | 10% | - |The 3rd color is the number of zeros, for example:
Capacitor color: Red, Red, Green, White, Red. So the capacity is:
22 000 00 pF = 2.2 Mfd, toleransi 10% dan V max = 250 Volt.Testing Elco Capacitors
Testing Elco
- Place the selector switch in the ohm meter (range) position.
- Attach the red plug to the positive leg of the Elco, and the black plug to the negative leg of the Elco.
- If the needle moves to the right, then back to the left, it means the elco is good.
- If the needle moves to the right then back to the left but is not full, it means the electrolytic capacitor is slightly damaged.
- If the needle moves to the right and then does not return to the left (stops), then the capacitor is leaking.
- If the needle does not move at all, it means the electrolytic capacitor is broken.
Additional Article (Abstract)
A capacitor is a device that can store energy in an electric field, by collecting the internal imbalance of electric charge. The capacitor has a unit called Farad. Discovered by Michael Faraday (1791-1867). The capacitor is now also known as a "capacitor", but the word "condenser" is still used today. First mentioned by Alessandro Volta, an Italian scientist in 1782 (from the Italian condensatore), regarding the ability of the device to store a high electric charge compared to other components. Most languages and countries that do not use English still refer to the Italian word "condensatore", such as the French condensateur, Indonesian and German Kondensator or Spanish Condensador.
Types of Capacitors
Based on its use, we divide capacitors into:
- Fixed capacitor (capacity value remains the same and cannot be changed)
- Electrolytic capacitor (Electrolite Condenser = Elco)
- Variable capacitor (capacity value can be changed)
4. Fixed capacitor
It is a capacitor whose value is constant and does not change. Fixed capacitors come in three forms:
Ceramic Capacitor
The shape is round thin, there are square ones in red, green, brown and others. In installation on the circuit board (PCB), it can be reversed because it does not have positive and negative legs. Has a capacity ranging from several pico Farads to hundreds of Kilopiko Farads (KpF). With a maximum working voltage of 25 volts to 100 volts, but there are also those that reach thousands of volts.
For example, if the body is written = 203, the capacity value is = 20,000 pF = 20 KpF = 0.02 µF. If the body is written = 502, the capacity value is = 5,000 pF = 5 KpF = 0.005 µF.
Capacitor polyester
Basically the same as ceramic capacitors as well as how to calculate their values. The shape is rectangular like candy. Usually has red, green, brown and so on.
Paper capacitor
This paper capacitor is often also called a padder capacitor. For example, on a radio it is installed in series from the oscillator coil to the variable capacitor. The capacity values used in the oscillator circuit include:
- Capacity 200 pF - 500 pF for medium wave (MW) area = 190 meters - 500 meters.
- Capacity 1,000 pF - 2,200 pF for short wave (Short Wave / SW) SW 1 = 40 meters - 130 meters.
- Capacity 2,700 pF - 6,800 pF for SW wave areas 1, 2, 3 and 4, = 13 meters - 49 meters.
5. Electrolytic capacitor
Electrolytic Condenser or Electrolytic Condenser (often abbreviated as Elco) is a capacitor that is usually shaped like a tube, has two poles of positive and negative polarity legs, marked by a long positive leg while the short negative or near the minus sign (-) is the negative leg. The capacity value is from 0.47 µF (microFarad) to thousands of microFarads with a working voltage of several volts to thousands of volts.
Various symbols for Electrolytic Capacitors in electronic schematics:
In addition to electrolytic capacitors that have polarity on their legs, there are also capacitors that have polarity, namely solid tantalum capacitors.
6. Capacitor variable
Variable and trimmer capacitors are types whose capacity can be changed. These capacitors can change their capacity because they physically have a shaft that can be rotated using a screwdriver.
Capacitor variable
Variable capacitors are made of metal, have a maximum capacity of around 100 pF (picoFarad) to 500 pF (100pF = 0.0001µF). Variable capacitors with antenna coils and oscillator coils function as selectors of certain frequency waves to be captured.
Capacitor trimmer
While the trimmer capacitor is installed parallel with the variable capacitor to adjust the selection of the frequency wave. The trimmer capacitor has a capacity below 100 pF (picoFarad).
Damage generally occurs if:
- Short circuit
- Half short circuit (transmitter wave reception becomes abnormal).