Like resistors the capacitance value of modulated paper and mica and ceramic capacitors is expressed by means of colour dots or bands while the capacitance of other types of capacitors is printed on them. The method of expression of the value of a carbon resistor is recognized internationally and their exists only one method. But, there are following four methods for the expression of the capacitance value of a capacitor:
1. Three dots method of E.I.A.:
The Electronics Industrial Association method is used for the expression of the capacitance value of moulded mica capacitors. Their working voltage is 500 volts and their tolerance is +/-20% and the capacitance value is expressed in Pico farads.
2. Six Dots Method of E.I.A.:
This method is also used for the expression of the capacitance value of moulded mica capacitors. The working voltage and the tolerance of the capacitor may also be expressed by this method and the capacitance value is expressed in Pico farads.
3. Six Dots Method of J.A.N. Or A.W.S.:
The joint Army Navy or American War Standard method is used for the expression of the capacitance value of moulded paper and mica capacitors. In this method also, the capacitance is expressed in Pico farads.
4. Colour Code of Ceramic Capacitors:
There are two methods:
(a) Dot Method:
In this method, 5 dots of different colours are marked on the capacitor. Out of 5 dots, the first one is thicker than others and then there are second, third, fourth and fifth dots. In this method also, the capacitance is expressed in Pico farads.
(b) Band Method:
In this method, 5 bands of different colours are marked on the capacitor in place of dots. The first band indicates temperature coefficient, second band indicates first digit of the capacitance value, third band indicates second digit of the capacitance value, fourth band indicates the no. of zeros to be put after two digits and the fifth band indicates tolerance value of the capacitor.
The colour code for this method is shown in figure. In this method also the capacitance value is expressed in Pico farads.
1. Three dots method of E.I.A.:
The Electronics Industrial Association method is used for the expression of the capacitance value of moulded mica capacitors. Their working voltage is 500 volts and their tolerance is +/-20% and the capacitance value is expressed in Pico farads.
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| Three dots method of E.I.A |
2. Six Dots Method of E.I.A.:
This method is also used for the expression of the capacitance value of moulded mica capacitors. The working voltage and the tolerance of the capacitor may also be expressed by this method and the capacitance value is expressed in Pico farads.
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| Six dots method |
3. Six Dots Method of J.A.N. Or A.W.S.:
The joint Army Navy or American War Standard method is used for the expression of the capacitance value of moulded paper and mica capacitors. In this method also, the capacitance is expressed in Pico farads.
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| Six dots method of J.A.N. |
4. Colour Code of Ceramic Capacitors:
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| Five dots method |
There are two methods:
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| Colour code of ceramic capacitors |
(a) Dot Method:
In this method, 5 dots of different colours are marked on the capacitor. Out of 5 dots, the first one is thicker than others and then there are second, third, fourth and fifth dots. In this method also, the capacitance is expressed in Pico farads.
(b) Band Method:
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| Band method for ceramic capacitors |
In this method, 5 bands of different colours are marked on the capacitor in place of dots. The first band indicates temperature coefficient, second band indicates first digit of the capacitance value, third band indicates second digit of the capacitance value, fourth band indicates the no. of zeros to be put after two digits and the fifth band indicates tolerance value of the capacitor.
The colour code for this method is shown in figure. In this method also the capacitance value is expressed in Pico farads.
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| Examples |
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