**Standard Resistor values:**

IEC60063 defines the
preferable numbers for passive components. There are E6, E12, E24, E48, E96,
E192 series resistors. E6 series resistors have 20% tolerance. E12 series
resistors have 10% tolerance. E24 series resistors have 5% tolerance. E48
resistors have 2% tolerance. E96 resistors have 1% tolerance. E192 resistors
have 0.5% tolerance. 1% tolerance resistors are available in E24 series also. 0.1%,
0.25% resistors are also available in E192 series

__E6 Series (20%):__

__E12 Series (10%):__

__E24 Series (5%):__

__E48 Series (2%):__

__E96 Series (1%):__

__E192 Series (0.5%, 0.2%, 0.1%):__

Standard
resistance value can be obtained by multiplying any value shown in above tables
by 10^x
(i.e. 10 to the power x). ‘x’ can be any integer.

In 4 band resistor
code, first 2 lines represent significant, third line represents multiplier, 4

^{th }line represents tolerance. In 5 band resistor code 4^{th}line is the multiplier and 5^{th}line represents tolerance. In 6 band resistor 4^{th}line is the multiplier and 5^{th}line is tolerance, 6^{th}line is temperature coefficient.
For example consider a
5 band resistor with first line Brown, 2&3

^{rd}line Black, 4^{th}line represents Red, 5^{th}line is Brown. Then resistance value is calculated as
Value is
100x100=10000=10Kohm

Since 5^{th}line is Brown, tolerance is 1%. So the resistor is a 10K, 1% resistor.

**SMD Resistor marking:**

SMD
chip resistors have 3-digit or 4-digit code marked on them. Recently new coding
system (EIA-96) is being used for marking.

__3-digit code:__

In the 3-digit code, first two numbers represent significant digits. Third digit is multiplier. Third digit represents power of 10. For example consider above marking, here multiplier (3

^{rd}digit) 4 means “10 to the power 4” is the multiplier. So resistance value is 10 X = 100K Ohm

‘R’
is used to indicate decimal point in resistance value. For example ‘10R’ is the
marking on the resistor then, it is 10ohm resistor. ‘4R7’ is the marking then
resistance value is 4.7Ohm.

__4-digit code:__

In
the 4-digit code, first three numbers represent significant digits. Fourth
digit is multiplier. Fourth digit represents power of 10. For example consider
above marking, here multiplier (4

^{th}digit) 2 means “10 to the power 2” is the multiplier. So resistance value is 150 X = 15K Ohm
‘R’
is used to indicate decimal point in resistance value. For example ‘10R0’ is
the marking on the resistor then, it is 10ohm resistor. ‘470R’ is the marking
then resistance value is 470 Ohm.

__EIA-96 code:__

In this code, first two
numbers represent significant information about resistance value. Refer to the
below table for the equivalent resistance value against two digit number. Third
alphanumeric is multiplier.

__Multiplier:__

For example marking on
the resistor is ‘10C’, and then resistance value is 124 X 100 =12.4K ohm (10
means from table 124).

**Resistor packages:**

The
following are the surface mount packages and their corresponding wattage and
dimensions.

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