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Standard EIA Decade Resistor Values Table

    The Electronic Industries Association (EIA), and other authorities, specify standard values for resistors, sometimes referred to as the "preferred value" system. The preferred value system has its origins in the early years of the last century at a time when most resistors were carbon-graphite with relatively poor manufacturing tolerances. The rationale is simple - select values for components based on the tolerances with which they are able to be manufactured. Using 10% tolerance devices as an example, suppose that the first preferred value is 100 ohms. It makes little sense to produce a 105 ohm resistor since 105 ohms falls within the 10% tolerance range of the 100 ohm resistor. The next reasonable value is 120 ohms because the 100 ohm resistor with a 10% tolerance is expected to have a value somewhere between 900 and 110 ohms. The 120 ohm resistor has a value ranging between 110 and 130 ohms. Following this logic, the preferred values for 10% tolerance resistors between 100 and 1,000 ohms would be 100, 120, 150, 180, 220, 270, 330 and so on (rounded appropriately); this is the E12 series shown in the table below.
    The EIA "E" series specify the preferred values for various tolerances. The number following the "E" specifies the number of logarithmic steps per decade. The table below is normalized for the decade between 100 and 1,000. The values in any decade can be derived by merely dividing or multiplying the table entries by powers of 10. The series are as follows:

E6 20% tolerance,
E12 10% tolerance,
E24 5% tolerance (and usually 2% tolerance),
E48 2% tolerance,
E96 1% tolerance,
E192 .5, .25, .1% and higher tolerances.

           Standard EIA Decade Values Table (100 to 1,000 Decade)

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