To indicate the values or ratings of electronic components such as resistors,capacitors, inductors and many others, electronic color code scheme is applied which will be discussed further in this site. But if you need to identify the wires used in telecommunications cables, a separate color code scheme is used which is referred to as the 25-pair color code.

In the early 1920s, Radio Manufacturer’s Association (now part of Electronic Industries Alliance) developed the electronic color code which was known as EIA-RS-297. At present the international standard used for electronic color code is IEC 60062.

Colorbands are normally used (particularly on resistors) because they are more economical in terms of construction costs and are easily printed on small components.  But this method has a downside especially to color blind people. When components are exposed to extreme heat or became dusty and dirt build-up, it will be very difficult to know the difference of brown, red and orange color. However, in modern electronics, state of the art printing technology made way to print numbers for small components more practical and convenient to use.

The values of resistors are always expressed in ohms (symbol Ω), capacitors in picofarads (pF) and inductors in microhenries (µH).

• Band A is the first significant number of the component value
• Band B is the second significant number
• Band C is the decimal multiplier
• Band D, if present, indicates the tolerance of the value in percent (if not present it means 20% tolerance)

For example, in a resistor with color bands of yellow, violet, red and gold will have 4 as its first digit (see table below for yellow), 7 as the second digit (violet), next are 2 (red) zeros, or equivalent to 4,700 ohms. The gold color indicates that the tolerance is ±5%, thus the actual value of the resistance could be anywhere between 4,465 ohms and 4,935 ohms.

Resistors may also have a fifth band which indicates component failure rate or reliability; especially resistors used in military (see MIL-HDBK-199 for more details).Resistors which require strict tolerance usually have three bands rather than two and more often it has another band indicating the temperature coefficient (ppm/K).

All coded components should have a minimum of two value bands and a multiplier, additional bands are optional (see table below).

The standard color code per EN 60062:2005 is as follows:

For example, a resistor which has the following colors: yellow, violet, yellow and brown (read from left to right). The first two colors or bands will give the value of 4 and 7. The third color, which is another yellow, is the multiplier equivalent to x104. The overall value of the resistor will be 47 x 104 Ω or equivalent to 470,000 Ω or for simplicity 470 kΩ.  Thus, the brown color is the tolerance which is ±1%.

Resistors values can be determined by their tolerances. These values repeat for every order of magnitude; 1.2, 12, 120, and so forth. This is very helpful because the digits (the first two or three colors) will always be of the same colors, which as a result is much simpler to identify.

Don’t be surprised that zero ohm resistors are also fabricated; these are made of wire links enclosed in a resistor shape body which if error occurred can be replaced by another resistor value especially when using an automatic insertion machine. Zero ohmresistors are marked by a single black band.

For radial-lead composition resistors that are often times used in vacuum-tube equipment, “body-end-dot” or “body-tip-spot” system is implemented. The body color indicates the first band, the color of the end of the resistor will be the second band and the dot will be the multiplier which is found at the middle of the resistor. The other end of the resistor which is the gold or silver color will be the tolerance, but if it’s not present then assumes that it has a 20% tolerance.

In ceramic capacitors, the extra bands indicate the voltage rating class and temperature coefficient characteristics. For tubular paper capacitors, a broad black band is used to identify the end which has the outer electrode; this end allows thecapacitor to be connected to the chassis ground which gives protection against hum and noise pickup.

Polyester film and “gum drop” tantalum electrolytic capacitors also come in color coded scheme to identify the value, working voltage and tolerance.

Mnemonics

A mnemonic can be very useful in matching the first letters of the color codes by order of increasing magnitude. Below are some of the variations.

Bad boys rape our young girls behind victory garden walls.
Bad boys run our young girls behind victory garden walls.
Bad boys rape our young girls but Violet gives willingly.
Big boys race our young girls but Violet generally wins.

The tolerance codes, gold, silver and none, are not usually included in the mnemonics; one example that includes them is:

Bad beer rots our young guts but vodka goes well – get some now.