How to decide and calculate the values of the resistors
Nov 22nd, 2009 by admin
In some circuit boards, carbon resistors with color codes are used but in most of the circuits of electronic devices, you will find smaller resistors with values written on them. If you are confused about deciding or calculating the values of the resistors by seeing the resistors, then I am just sharing some simple and basic tips about resistors.
In the carbon color coded resistor with four color bands, the first two colors indicate the first two digits of the resistor’s value. The third band gives the multiplier value and the fourth color band indicates the tolerance of the resistor (Gold for 5% tolerance and silver for 10% tolerance). Refer the below chart for the values of the different color bands in the resistors for different bands.
If you have any difficulty in remembering the color value at the above chart, then many formulae are invented for easy remembrance of the color sequence. I am sharing some of the tips. But it is not important to use these formulae because after Black, Brown, (six spectrum color without Indigo, ROYGBV), Gray and White.
1. Bright Boys Rave Over Young Girls But Veto Getting Wed
2. Bad Boys Ravage Only Young Girls, But Violet Gives Willingly
3. Bad beer rots our young guts but vodka goes well
In some cases, five band resistors are used and in those cases, you can calculate the value of the resistor by using the table below:
In many cases manufactured resistor is usually labeled with the nominal value. The rectangualr resistors usually contain numbers that indicate a resistance and a multiplier. If there is three or four digits in the resistor, then the first numbers indicate the resistance value and the last number refers to the number of the zeros in the multiplier. And if there is one R is the resistor value, then it indicates the position of the decimal point. Refer the example below for more understanding about resistor value reading:
3002 means 300 X 10^2 = 30K Ohm
3R5 means 3.5 Ohm