Thursday, 2 January 2014

BASIC ELECTRONICS CAPACITOR



Capacitor Colour Codes

Generally, the actual values of Capacitance, Voltage or Tolerance are marked onto the body of the capacitors in the form of alphanumeric characters. However, when the value of the capacitance is of a decimal value problems arise with the marking of a "Decimal Point" as it could easily not be noticed resulting in a misreading of the actual value. Instead letters such as p (pico) or n (nano) are used in place of the decimal point to identify its position and the weight of the number.
For example, a capacitor can be labelled as, n47 = 0.47nF, 4n7 = 4.7nF or 47n = 47nF and so on. Also, sometimes capacitors are marked with the capital letter K to signify a value of one thousand pico-Farads, so for example, a capacitor with the markings of 100K would be 100 x 1000pF or 100nF.
To reduce the confusion regarding letters, numbers and decimal points, an International colour coding scheme was developed many years ago as a simple way of identifying capacitor values and tolerances. It consists of coloured bands (in spectral order) known commonly as the Capacitor Colour Codesystem and whose meanings are illustrated below:

Capacitor Colour Code Table

Colour
Digit
A
Digit
B
Multiplier
D
Tolerance
(T) > 10pf
Tolerance
(T) < 10pf
Temperature Coefficient
(TC)
Black
0
0
x1
± 20%
± 2.0pF

Brown
1
1
x10
± 1%
± 0.1pF
-33x10-6
Red
2
2
x100
± 2%
± 0.25pF
-75x10-6
Orange
3
3
x1,000
± 3%

-150x10-6
Yellow
4
4
x10,000
± 4%

-220x10-6
Green
5
5
x100,000
± 5%
± 0.5pF
-330x10-6
Blue
6
6
x1,000,000


-470x10-6
Violet
7
7



-750x10-6
Grey
8
8
x0.01
+80%,-20%


White
9
9
x0.1
± 10%
± 1.0pF

Gold


x0.1
± 5%


Silver


x0.01
± 10%



Capacitor Voltage Colour Code Table

Colour
Voltage Rating (V)
Type J
Type K
Type L
Type M
Type N
Black
4
100

10
10
Brown
6
200
100
1.6

Red
10
300
250
4
35
Orange
15
400

40

Yellow
20
500
400
6.3
6
Green
25
600

16
15
Blue
35
700
630

20
Violet
50
800



Grey

900

25
25
White
3
1000

2.5
3
Gold

2000



Silver





Capacitor Voltage Reference

  • Type J  -  Dipped Tantalum Capacitors.
  •  
  • Type K  -  Mica Capacitors.
  •  
  • Type L  -  Polyester/Polystyrene Capacitors.
  •  
  • Type M  -  Electrolytic 4 Band Capacitors.
  •  
  • Type N  -  Electrolytic 3 Band Capacitors.

An example of the use of capacitor colour codes is given as:

Metalised Polyester Capacitor

Disc & Ceramic Capacitor


The Capacitor Colour Code system was used for many years on unpolarised polyester and mica moulded capacitors. This system of colour coding is now obsolete but there are still many "old" capacitors around. Nowadays, small capacitors such as film or disk types conform to the BS1852 Standard and its new replacement, BS EN 60062, were the colours have been replaced by a letter or number coded system.
Generally the code consists of 2 or 3 numbers and an optional tolerance letter code to identify the tolerance. Where a two number code is used the value of the capacitor only is given in picofarads, for example, 47 = 47 pF and 100 = 100pF etc. A three letter code consists of the two value digits and a multiplier much like the resistor colour codes in the resistors section.
For example, the digits 471 = 47*10 = 470pF. Three digit codes are often accompanied by an additional tolerance letter code as given below.

Capacitor Tolerance Letter Codes Table


Letter
B
C
D
F
G
J
K
M
Z
Tolerance
C <10pF ±pF
0.1
0.25
0.5
1
2




C >10pF ±%


0.5
1
2
5
10
20
+80-20
Consider the capacitor below:

The capacitor on the left is of a ceramic disc type capacitor that has the code 473J printed onto its body. Then the 4 = 1st digit, the 7 = 2nd digit,
the 3 is the multiplier in pico-Farads, pF and the letter J is the tolerance and this translates to:

   47pF * 1,000 (3 zero's) = 47,000 pF , 47nF or 0.047 uF

 the J indicates a tolerance of +/- 5%
Then by just using numbers and letters as codes on the body of the capacitor we can easily determine the value of its capacitance either in Pico-farad's, Nano-farads or Micro-farads and a list of these "international" codes is given in the following table along with their equivalent capacitances.

Capacitor Letter Codes 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
0.022
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
0.0022
222
2200000
2200
2.2
225
3300
3.3
0.0033
332
3300000
3300
3.3
335

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