Resistor's have a standard color code to identify their resistance value.
1. The color of the first band indicates the value of the first significant digit.
2. The color of the second band indicates the value of the second significant digit.
3. The third color band represents a decimal multiplier by which the first two digits must be multiplied to obtain the resistance value of the resistor.
The colors for the bands and their corresponding values are shown in the table below.
Table for identifying standard resistor values.
When measuring resistors, you will find situations in which the quantities to be measured may be extremely large, and the re-sulting number using the basic unit, the ohm, may prove too cumbersome.
Therefore, a metric system prefix is usually attached to the basic unit of measurement to provide a more manageable unit.
Two of the most commonly used prefixes are kilo and mega. Kilo is the prefix used to represent thousand and is abbreviated k. Mega is the prefix used to represent million and is abbreviatedM.
Resistors are the most common components used in electronics. The technician must identify, select, check, remove, and replace resistors. Resistors and resistor circuits are usually the easiest branches of electronics to understand.
The resistor color code sometimes presents problems to a technician. It really should not, because once the resistor color code is learned, you should remember it for the rest of your life.
Black, brown, red, orange, yellow, green, blue, violet, gray, white—this is the order of colors you should know automatically. There is a memory aid that will help you remember the code in its proper order.
Each word starts with the first letter of the colors. If you match it up with the color code, you will not forget the code.
Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8. White=9.
Bad boys race our young girls behind victory garden walls.
There are many other memory aid sentences that you might want to ask about from experienced technicians. You might find one of the other sentences easier to remember.
There is still a good chance that you will make a mistake on a resistor's color band. Most technicians do at one time or another. If you make a mistake on the first two significant colors, it usually is not too serious.
If you make a miscue on the third band, you are in trouble, because the value is going to be at least 10 times too high or too low. Some important points to remember about the third band are:When the third band is . . . .Black, the resistor’s value is less than 100 ohms.Brown, the resistor’s value is in hundreds of ohms.Red, the resistor’s value is in thousands of ohms.Orange, the resistor’s value is in tens of thousands of ohms.Yellow, the resistor’s value is in hundreds of thousands of ohms.Green, the resistor’s value is in megohms.Blue, the resistor’s value is in tens of megohms or more.
Although you may find any of the above colors in the third band, red, orange, and yellow are the most common. In some cases, the third band will be silver or gold. You multiply the first two bands by 0.01 if it is silver, and 0.1 if it is gold.
The fourth band, which is the tolerance band, usually does not present too much of a problem. If there is no fourth band, the resistor has a 20-percent tolerance; a silver fourth band indicates a 10-percent tolerance; and a gold fourth band indicates a 5-percent tolerance. Resistors that conform to military specifications have a fifth band. The fifth band indicates the reliability level per 1,000 hours of operationas follows:Fifth band color LevelBrown 1.0%Red 0.1%Orange 0.01%Yellow 0.001%
For a resistor whose the fifth band is color coded brown, the resistor’s chance of failure will not exceed 1 percent for every 1,000 hours of operation.
may seem like a lot of information to absorb, but knowing how to
identify resistors quickly by their color codes will make selecting the
correct resistor much easier.