Module 3.4
Inductor Colour Codes
- After studying this section, you should:
- • Know the EIA and military standard colour codes for inductors.
- • Be able to calculate the value of colour coded inductors.
Fig 3.4.1 Four Band Standard EIA Colour Code For Inductors.
Therefore value = 27 x10 = 270µH +/-20%
| Band | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Meaning | 1st Digit | 2nd Digit | Multiplier (No. of zeros) | Tolerance % |
| Gold | x 0.1 (divide by 10) | +/-5% | ||
| Silver | x 0.01 (divide by 100) | +/-10% | ||
| Black | 0 | 0 | x1 (No Zeros) | +/-20% |
| Brown | 1 | 1 | x10 (0) | |
| Red | 2 | 2 | x100 (00) | |
| Orange | 3 | 3 | x1000 (000) | |
| Yellow | 4 | 4 | x10000 (0,000) | |
| Green | 5 | 5 | ||
| Blue | 6 | 6 | ||
| Violet | 7 | 7 | ||
| Grey | 8 | 8 | ||
| White | 9 | 9 |
Note: If no Band 4 is used, tolerance is also +/-20%
Fig 3.4.2 Five Band Military Standard Inductor Colour Code
| Band | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Meaning (See Notes) |
Mil. Spec. | Digit or Dec. point |
Digit or Dec. point |
Digit (or Multiplier) |
Tolerance % |
| Gold | Decimal point |
Decimal point |
+/-5% | ||
| Silver | Always Silver double width |
+/-10% | |||
| Black | 0 | 0 | 0 (or x 1) |
+/-20% | |
| Brown | 1 | 1 | 1 (or x 10) |
+/-1% | |
| Red | 2 | 2 | 2 (or x 100) |
+/-2% | |
| Orange | 3 | 3 | 3 (or x 1,000) |
+/-3% | |
| Yellow | 4 | 4 | 4 (or x 10,000) |
+/-4% | |
| Green | 5 | 5 | 5 | ||
| Blue | 6 | 6 | 6 | ||
| Violet | 7 | 7 | 7 | ||
| Grey | 8 | 8 | 8 | ||
| White | 9 | 9 | 9 |
Notes:
The military standard for cylindrical inductors specifies 5 coloured bands The same colours are used as in the EIA 4 band code, but:
For band 1, a double width sliver band is used to signify Military Standard.
For values less than 10µH:
Bands 2, 3 and 4 indicate the value of inductance in µH
A gold band might be used in either band 2 or band 3. In either of these two bands, gold indicates a decimal point and band 4 is used as a digit instead of a multiplier band.
When no gold band is present in bands 2 or 3, band 4 is a multipier band.
For example:
- If bands 2,3 and 4 are red, gold, red the value would be 2.2 µH
- If bands 2,3 and 4 are gold, yellow, violet the value would be 0.47 µH (470nH)
Band 5 indicates the tolerance between 1% and 20%
For values of 10µH or more:
Bands 2 and 3 represent basic value, and band 4 gives the number of zeros.
For example:
If bands 2, 3 and 4 are red, violet, orange the value would be 27000 µH
Surface Mount Device(SMD) or Chip Inductor Codes.
For inductors of a very small physical size, coloured dots may be used instead of bands. In such cases, The silver dot indicating a Military (Mil) specification will be larger than the other dots and will be placed a the beginning of the dot sequence.
In some cases only a single coloured dot is used,and for their meaning it is neccesary to refer to individual manufacturers data for accurate interpretation.
Dot code examples from Coilcraft Inc. http://www.coilcraft.com/colrcode.cfm
Dot code examples from Viking Tech Corporation. http://www.vikingamerica.com/ftp/NL.pdf