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Inductors can be labeled with a number of different ways. The most common are text codes and color codes.

Axial-inductor-on-PCB-board

Text Marking[]

Various-inductors-with-text-labels

  • xRx values are in micro Henries (μH)
  • Three digit values are in nano Henries (nH) or micro Henries (μH), depending on manufacturers choice
  • First two digits are the value
  • Third digit is the multiplier (or number of zeros added to the value)
  • If there is an R, its acts as a decimal point, and there is no multiplier
  • Examples:
    • 472 = 47*102nH = 4700nH = 4.7μH (Coilcraft)
    • 472 = 47*102μH = 4700μH = 4.7mH (Bourns)
    • 4R7 = 4.7μH
  • Suffix
    • Sometimes the precision of the inductor will be marked, using a final letter F, G, J, K, or M
      • F = +/-1%
      • G = +/-2%
      • J = +/-5%
      • K = +/-10%
      • M = +/-20%

Color Code Markings[]

Inductors can be marked by colored bands or colored dots. Each color represents a value.

bands may be spaced evenly of have a gap between bands C and D

Band A Band B Band C Band D
1st Digit 2nd Digit Multiplier Tolerance
1 Silver 10-2 (0.01uH) Gold 5%
Gold 10-1 (0.1uH) Silver 10%
Black 0 Black 100 (1uH) Black 20%
Brown 1 Brown 1 Brown 101 (10uH)
Red 2 Red 2 Red 102 (100uH)
Orange 3 Orange 3 Orange 103 (1000uH)
Yellow 4 Yellow 4 Yellow 104 (10000uH)
Green 5 Green 5 Yellow 104 (10000uH)
Blue 6 Blue 6
Violet 7 Violet 7
Gray 8 Gray 8
White 9 White 9

note: brown and violet can look very similar on some components. Violet and white can also look similar sometimes


Example 47 micro Henry

Axial-inductor-on-PCB-board
  • Band colors:
    • 1st band: yellow=4
    • 2nd band: violet=7
    • 3rd band: black=10^0=1
  • Inductor value = 47x10^0uH = 47uH
    • 4th band: silver = 10% tolerance
    • inductance=47+-10

References[]

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