In electronic repair, most of the time i came across five band resistor color code. The purpose of using the five colour band resistor in a circuit is that it provide a more accurate value compare to the four color band. For example in order to get the value of 22.6kohm, with four colors band resistor you will not be able to find it. The most you can get is 22k
(red,red,orange and gold). If with the five color band you will be able to calculate it (red, red, blue, red, brown)the last color which is brown represent 1% tolerance. You may go to google search engine and type resistor color code, resistor color coding, resistor color code calculator, or resistor color code chart to know more about how to calculate a five band resistor values.
If you open up an analog multimeter you will understand what i mean. Most of the resistor circuit inside
the multimeter are using five color band. Why? Because the reading that you get whenever you measure current,
voltage or ohm, the panel will show the nearest value. For instance, if you measure a 9v battery
the needle will point to may be 8.9v,9v,or 9.1 volt. If that particular multimeter was designed
using four color band resistor the result that it gets may be 8.5v,9.5v or even 10 volt. In other
words the use of five color band resistor is to make a circuit more precise and output the desire
result as what the engineers want it to be.
There's a interesting five color band resistor which is unique.
In fact i have already seen quite a number of them. I will reveal the calculation about this
unique five color band resistor. The colors are orange, orange, red, gold, white.
Actually it is a four color band resistor. Just ignore the white color and proceed to calculate
using the four color band formula. As to why the resistor manufacturers add this 'extra' white
band i really do not know. However, from forum someone said that it is for the military purposes.
If you know the answer i would like you to email me so that i can share with other fellow
electronic repairer thru this info repairing newsletter.
Jestine Yong is a electronic repairer and a writer. For more information on electronic repair please visit his website at
http://www.noahtec.com/electronic-repair-articles.htm