How to Identify Capacitor

Capacitors have extensive use in electrical circuits and devices but finding the right capacitor having adequate values is necessary for smooth operation of circuits. For this, it is imperative that one should be able to read the specifications of the capacitor because the specifications of a capacitor are printed on it in the form of code. The primary reason behind the use of code for its specification is due to the fact that the size of the capacitors is usually small. However, the big capacitors usually don’t have their specifications written in the form of code due to ample space.

Outline:

How to Identify Capacitor

• Aluminum Electrolytic Capacitors
• Tantalum Capacitors
• Ceramic Capacitors

Conclusion

How to Identify Capacitor

The specifications of a capacitor include its capacitance, tolerance, temperature range, and range for the voltage it can bear which is also called working voltage. Some capacitors include CM or DM in their code, and this means it is a military-grade capacitor and in that case, consult the military-grade capacitor specification chart.

The specifications of capacitors vary based on their internal composition, which includes dielectric, material of electrodes, and electrolyte. To identify the specifications of a capacitor we need to divide them based on their configuration because of the variation in the codes, shapes, and sizes. There are three major specifications of the capacitors that are: capacitance, voltage, and tolerance. The table for voltage codes is given below:

Code	Voltage	Code	Voltage	Code	Voltage	Code	Voltage
0E	2.5VDC	1A	10 VDC	2A	100 VDC	3L	1.2 KVDC
0G	4.0VDC	1C	16 VDC	2Q	110 VDC	3B	1.25 KVDC
0L	5.5VDC	1D	20 VDC	2B	125 VDC	3N	1.5 KVDC
0J	6.3VDC	1E	25 VDC	2C	160 VDC	3C	1.6 KVDC
0K	80VDC	1V	35 VDC	2Z	180 VDC	3D	2 KVDC
		1G	40 VDC	2D	200 VDC	3E	2.5 KVDC
		1H	50 VDC	2P	220 VDC	3F	3 KVDC
		1J	63 VDC	2E	250 VDC	3G	4 KVDC
		1M	70 VDC	2F	315 VDC	3H	5 KVDC
		1U	75 VDC	2V	350 VDC	3I	6 KVDC
				2G	400 VDC	3J	6.3 KVDC
				2W	450 VDC	3U	7.5 KVDC
				2J	630 VDC	3K	8 KVDC
				2K	800 VDC	4A	10 KVDC

Below the image shows two capacitors having a code printed on them their rated voltage will be:

The codes for the values of tolerance are given below:

Code	Tolerance	Code	Tolerance
A	± 0.05	K	± 10
B	± 0.1	L	± 15
C	± 0.25	M	± 20
D	± 0.5	N	± 30
E	± 0.5	P	–0%, +100%
F	± 1	S	–20%, +50%
G	± 2	W	–0%, +200%
H	± 3	X	–20%, +40%
J	± 5	Z	–20%, +80%

In small capacitors like tantalum and ceramic capacitors, you will always find the code having three numbers. Among these numbers the first two will be the capacitance and the third one will be the prefix that is the multiplier, here is the table for it:

Number	Multiplier
0	1
1	10
2	100
3	1000
4	1000 0
5	1000 00
6	1000 000

On the surface mount capacitors where the space is limited, usually to show the decimal point R letter is used. If the written code is 4R1 then it means that the value is 4.1:

Aluminum Electrolytic Capacitors

These capacitors have an oxide layer as a dielectric that is sprayed onto its electrodes, and it could be aluminum metal oxide. There are a variety of ways in which the specifications of a capacitor are printed on it.

Polarity

These capacitors are polarized which means that if connected in the opposite polarity it can be damaged. Usually, these capacitors have only one side marked like this:

This means that this side has a negative terminal so when you see there are such markings for the polarity, then it means that this is a polarized capacitor. Some surface-mount capacitors can have different marking designs to show the polarity of the capacitor:

Some capacitors may have polarity signs printed on the metal body right next to the terminals. Moreover, in some capacitors, the terminals are colored using the same color code used for live and ground wire. Some capacitors do not have the markings for the terminals, but the polarity can be determined by the length of its terminals. The length of the positive terminal is larger than that of the negative terminal:

Capacitance

The unit for capacitance is farads and to simplify the values of capacitance there are different prefixes used like micro, pico milli, and nano. Some capacitors have mentioned the prefix along with the prefix and the unit of capacitance.

On surface-mount capacitors the space is limited so only the value is written, in that case, the prefix can be assumed as micro:

Voltage Rating

Another specification mentioned on the capacitor is the voltage rating under which the capacitor will operate to its full potential. Usually, one fixed voltage is printed in the capacitor but in the case of bigger capacitors a voltage range is given:

Some of the electrolytic capacitors come with voltage values written in the form of codes as in the image below the first capacitor has the code C which means it has a rated voltage of 16V:

Tolerance

Just like resistors capacitors also have tolerance but only for those whose capacitance is low, it is basically the range under which the capacitance can vary. So for tolerance there is a code printed on the capacitors and if there is no code present then it means the tolerance lies between ± 20% to ±80 %. Here is an example of a capacitor having a four-letter code printed on it that 107D and in that case, the capacitance will be 100 µF and the tolerance will be 0.5%:

Sometimes the value of tolerance is already mentioned on the capacitor like this:

Temperature

The temperature in the surroundings of the capacitor greatly affects the working of the capacitor, so normally the temperature range is printed on the capacitor:

Tantalum Capacitors

Like the aluminum capacitors, these are also polarized but instead of having aluminum in their composition they have tantalum. These capacitors have higher capacitance and low operating voltage which look like this:

The specifications of the tantalum capacitors can also be written in other ways, as in the image below:

Ceramic Capacitors

The ceramic capacitors have a dielectric made from ceramic materials, they have comparatively lower capacitance and are non-polarized which means that they can be used in AC circuits. The rate voltage ranges from a few volts up to kilo volts, these types of capacitors look like this:

Now, to further sum up how the capacitor specifications can be interpreted, here is an image that gives the overview:

 

Conclusion

Capacitor specification in any circuit is based on the respective circuit requirement, the specification includes its capacitance (capacity to store charge), working voltage, tolerance temperature, and internal composition. The big-size capacitors have their specifications printed on them clearly whereas the small-size capacitors present their specifications in the form of codes that are printed on them due to the limitation of space. So, to crack the code there are specified tables for tolerance, voltage and capacitance.