|
|
|
Resistor Selector |
Determine the correct resistor colour code by converting the numerical resistance value.
|
|
|
Instructions:
Enter the required numerical resistor value in ohms. Valid input for a 5k6 ohm resistor for
example is 5600. No commas or letters allowed.
Use the mouse to select the required accuracy % tolerance.
The correct colour code is subsequently displayed
Note:
Preferred Values
E12 Series E24 Series
10 10 33
12 11 36
15 12 39
18 13 43
22 15 47
27 16 51
33 18 56
39 20 62
47 22 68
56 24 72
68 27 82
82 30 91
|
Most resistors are so small that it is impractical to print their values on them using normal numeric characters. Instead, they are marked with a code using coloured bands.
Resistors made to tolerance of 5% and 10% are marked with 4 bands while higher precision types, such as 2%, 1 % or better, may be marked with 5 bands to allow for an extra digit of precision.
How to read 4-band codes:
At one end of the resistor there will be a gold, silver or brown tolerance band. This band is usually spaced apart from the other three bands. Start with the band nearest to the other end. Its colour represents the first digit of the resistor's value, as shown in the colour code chart. The next band represents the second digit of the resistor's value. The third band represents the decimal multiplier, that is, the number of zeroes that we have to put after the first two digits to arrive at the resistor's value. The final band gives us the tolerance of the resistor, silver for 10% types, gold for 5% types, brown for 1% types.
Lets take the default resistor shown in the program at the top of the page as an example. It's first band is yellow, representing '4' and the second band is violet, representing 7. The third band, the multiplier, is orange which tells us to add 3 zeroes to the number we already have. This is the same as multiplying it by 1,000. Thus the value of the resistor is 47,000 - fortyseven thousand ohms or 47k-ohms. Finally, the fourth band, being gold, indicates that the resistor has a 5% tolerance, that is, its actual value will be somewhere between 44,650 ohms and 49,350 ohms.
Some special high-voltage resistors use a yellow tolerance band in lieu of gold. This is simply because the metal particles in the gold paint might compromise the resistor's voltage rating.
What they mean.
Band one - first figure of value
Band two - second figure of value
Band three - number of zeroes/multiplier
Band four - tolerance
Tolerance band colours: brown 1%, red 2%, gold 5%, silver 10%, none 20%.
Reading 5-band resistors:
Because the final band on these resistors is usually brown or red, it can be a bit more difficult to know which end to start from. In most cases the first four bands are grouped a bit closer together than the fourth and fifth bands. The first two bands are read the same as they are on the 4- band types. The third band supplies the third digit of the value. The fourth band now becomes the multiplier and the fifth represents the tolerance.
For example, if the 5 bands are, from first to fifth, red/yellow/black/gold/brown, then the three significant digits of the value would be '240', the multiplier would be 0.1, and the tolerance 1%. Hence, this is the code fora 24 ohm, 1% resistor.
What they mean:
Band one - first figure of value
Band two - second figure of value
Band three - third figure of value
Band four - number of zeroes/multiplier
Band five - tolerance
|
|
|