Electronic Industry Association (EIA)
Standard EIA resistor values are used by the electronic industry in manufacturing and deciding values of resistor used in electronic circuits. The Electronic Industry Association also known as (EIA), decided the perfect or we can say preferred values of the resistor to manufacture. And the series is called as Standard Resistor Value. |
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Short Idea of Standard Resistor Value
Before the series got introduced there was no standard of making the preferred values of resistor. For example, let's say a company called XYZ made two resistors of value 100 ohms with a tolerance of 10% and 105 ohms with again 10% tolerance, Then this makes no sense as we already know that 100 ohms resistor has tolerance of 10% that means its value will range from 90 ohms to 110 ohms. Then there will be no need in making a resistor of 105 ohms value.History of Preferred Values
The history towards the invention of this series started in the early year of the last century when the resistor used to make up of carbon-graphite. To overcome the problem mentioned as above the Electronic Industry Association (EIA) decided some Standard Resistor Values and given the name "E" series of a resistor and "E" came from ("E" IA). And depending upon the tolerance value they made different series which we call it E3, E6, E12, E24, E48, E198 Standard Resistor value "E series".Tolerance Value of Each Series
From the no. of series each series has been made with reference to the particular tolerance value. To understand which value is associated with what value of tolerance let's have a look at the following table:-E3 series:- 50% tolerance (not in use)
E6 series:- 20% tolerance (rarely used)
E12 series:- 10% tolerance
E24 series:- 5% tolerance
E48 series:- 2% tolerance
E96 series:- 1% tolerance
E192 series:- 0.5%, 0.25%, 0.1% tolerance
Concept of Tolerance
So far we used the term tolerance, now you might be knowing what the tolerance mean... |
| Chart showing tolerance band identification |
but let us revise this again or this might be helpful for those who don't know about tolerance.
Let me tell you in a simple way,
When we tell that a resistor of value 100 ohms and 10% tolerance that means when we implement that resistor in a practical circuit we get its value in between 90 ohms to 110 ohms but not exactly 100 ohms.
From the above example, we can say that a tolerance means a % about which a value of resistor increase or decrease.
Form the above example it might be clear to you that what does tolerance is.
Concept of Decade
Now let's move towards the next topic Decade.You might have got a question that why only the value is like 3, 6,12, 24, 48, 96, 192 ???
Then read the following couple of lines...
The answer is due to Decade. A decade means the range of numbers from lower power of 10 up to the next conjugative power of 10.
That is from, let's say, (10 to 100) or from (100 to 1000) and so on...
But how this Decade is related to our question ???
E3 series mean values of a resistor having tolerance 50% so only 3 value of such a resistor is possible in each decade. again if we take an example of E6 series that means only 6 values of a resistor is possible in each decade. If we consider E12 series than only 12 values of a resistor with tolerance 10% is possible.
That's why these series were named so E3, E6, E12, E24, E48, E96, E192.
Now you are cleared that why the name is so "E" and why those particular ranges of a number.
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| E6, E12, E24 colour code chart |
standard Resistor Values in Decade from 1 to 10
Following are the values of each series in a particular decade.1) E3 values (50% tolerance)
1.0, 2.2, 4.7
2) E6 values (20% tolerance)
1.0, 1.5, 2.2, 3.3, 4.7, 6.8
3) E12 values (10% tolerance)
1.0, 1.2, 1.5, 1.8, 2.2, 2.7,
3.3, 3.9, 4.7, 5.6, 6.8, 8.2
4) E24 values (5% tolerance)
1.0, 1.1, 1.2, 1.3, 1.5, 1.6,
1.8, 2.0, 2.2, 2.4, 2.7, 3.0,
3.3, 3.6, 3.9, 4.3, 4.7, 5.1,
5.6, 6.2, 6.8, 7.5, 8.2, 9.1
5) E48 values (2% tolerance)
1.00, 1.05, 1.10, 1.15, 1.21, 1.27,
1.33, 1.40, 1.47, 1.54, 1.62, 1.69,
1.78, 1.87, 1.96, 2.05, 2.15, 2.26,
2.37, 2.49, 2.61, 2.74, 2.87, 3.01,
3.16, 3.32, 3.48, 3.65, 3.83, 4.02,
4.22, 4.42, 4.64, 4.87, 5.11, 5.36,
5.62, 5.90, 6.19, 6.49, 6.81, 7.15,
7.50, 7.87, 8.25, 8.66, 9.09, 9.53
6) E96 values (1% tolerance)
1.00, 1.02, 1.05, 1.07, 1.10, 1.13,
1.15, 1.18, 1.21, 1.24, 1.27, 1.30,
1.33, 1.37, 1.40, 1.43, 1.47, 1.50,
1.54, 1.58, 1.62, 1.65, 1.69, 1.74,
1.78, 1.82, 1.87, 1.91, 1.96, 2.00,
2.05, 2.10, 2.15, 2.21, 2.26, 2.32,
2.37, 2.43, 2.49, 2.55, 2.61, 2.67,
2.74, 2.80, 2.87, 2.94, 3.01, 3.09,
3.16, 3.24, 3.32, 3.40, 3.48, 3.57,
3.65, 3.74, 3.83, 3.92, 4.02, 4.12,
4.22, 4.32, 4.42, 4.53, 4.64, 4.75,
4.87, 4.99, 5.11, 5.23, 5.36, 5.49,
5.62, 5.76, 5.90, 6.04, 6.19, 6.34,
6.49, 6.65, 6.81, 6.98, 7.15, 7.32,
7.50, 7.68, 7.87, 8.06, 8.25, 8.45,
8.66, 8.87, 9.09, 9.31, 9.53, 9.76
7) E192 values (0.5% and lower tolerance)
1.00, 1.01, 1.02, 1.04, 1.05, 1.06,
1.07, 1.09, 1.10, 1.11, 1.13, 1.14,
1.15, 1.17, 1.18, 1.20, 1.21, 1.23,
1.24, 1.26, 1.27, 1.29, 1.30, 1.32,
1.33, 1.35, 1.37, 1.38, 1.40, 1.42,
1.43, 1.45, 1.47, 1.49, 1.50, 1.52,
1.54, 1.56, 1.58, 1.60, 1.62, 1.64,
1.65, 1.67, 1.69, 1.72, 1.74, 1.76,
1.78, 1.80, 1.82, 1.84, 1.87, 1.89,
1.91, 1.93, 1.96, 1.98, 2.00, 2.03,
2.05, 2.08, 2.10, 2.13, 2.15, 2.18,
2.21, 2.23, 2.26, 2.29, 2.32, 2.34,
2.37, 2.40, 2.43, 2.46, 2.49, 2.52,
2.55, 2.58, 2.61, 2.64, 2.67, 2.71,
2.74, 2.77, 2.80, 2.84, 2.87, 2.91,
2.94, 2.98, 3.01, 3.05, 3.09, 3.12,
3.16, 3.20, 3.24, 3.28, 3.32, 3.36,
3.40, 3.44, 3.48, 3.52, 3.57, 3.61,
3.65, 3.70, 3.74, 3.79, 3.83, 3.88,
3.92, 3.97, 4.02, 4.07, 4.12, 4.17,
4.22, 4.27, 4.32, 4.37, 4.42, 4.48,
4.53, 4.59, 4.64, 4.70, 4.75, 4.81,
4.87, 4.93, 4.99, 5.05, 5.11, 5.17,
5.23, 5.30, 5.36, 5.42, 5.49, 5.56,
5.62, 5.69, 5.76, 5.83, 5.90, 5.97,
6.04, 6.12, 6.19, 6.26, 6.34, 6.42,
6.49, 6.57, 6.65, 6.73, 6.81, 6.90,
6.98, 7.06, 7.15, 7.23, 7.32, 7.41,
7.50, 7.59, 7.68, 7.77, 7.87, 7.96,
8.06, 8.16, 8.25, 8.35, 8.45, 8.56,
8.66, 8.76, 8.87, 8.98, 9.09, 9.20,
9.31, 9.42, 9.53, 9.65, 9.76, 9.88.
Still, want more standard resistor value then have a lookup to below image...
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| Standard Resistor values from 100 to 1000 |
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