Resistor Color Code
Four-band resistor value from the band colors.
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The engineering
Bands read left to right with the tolerance band on the right. Brown-black-red-gold is the 1 kΩ ±5% you will pull out of every drawer for the rest of your life.
The mnemonic wars are eternal; the drawer label is more reliable.
Where this math comes from
Color coding was standardized by the Radio Manufacturers Association around 1928, when resistors were dipped dots on ceramic bodies too small to print on. The scheme survived because paint bands read at any orientation on a part that tumbles in a bin.
The system was later enshrined as EIA RS-279 and internationally as IEC 60062 — one of the oldest continuously used standards in electronics.
- 1928Radio Manufacturers AssociationStandardizes the resistor color code.
- 1952IECInternational color-code standard (now IEC 60062).
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