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Cracking the color code of resistor

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If you think these color code of resistor are to increase the beauty of resistor, to make it look presentable … hmm!   think again.

These resistors color code are the color code that tells you its resistance.

Before cracking the color codes of resistors, let’s have a quick view of what resistor is? What color code is?

As the resistors are small in size, it will be tough to read the description written on resistors.

Knowing the difficulty, designers come up with an idea of printing color codes on resistors. Moreover, these color stripes indicate resistance, tolerance, and temperature coefficient.

If you don’t have any idea how you read the color-coding of the resistor – worry not, we’ll explore together.

What is a Resistor?

Resistor is the small device used to limit the flow of electrical current. Secondly, to provide the specific voltage to an active device. It is a passive device comes in various sizes, shapes with multiple resistance according to your need in your electrical circuits.

Unless, you are not using any conductor or inductor in the circuit, ohm’s law applies to both direct current and alternating current circuits. The current through a resistor is inversely proportional to resistance and directly proportional to the voltage across it.

V= I R

Types of Resistor

Carbon-composition resistors are the most common resistors’ type; resistance depends upon the proportion of fine granulated carbon is jumbled with the clay and hardened.

We all know that carbon is a good conductor, and if we use an excessive amount of carbon, then more current will pass through it. It means the resistance of the carbon composition resistor is inversely proportional to the carbon.

Resistor Symbol

Resistor Color Code

If we look carefully at a resistor, there are colors coated on its surface, and these colors represent the special meaning behind it.

Three and four-band resistors are used in electronic circuits, and five and six bands resistors have high precisions.

Color codes not only state the resistance but also narrate the tolerance and heating coefficient. Moreover, we could also find out the resistance by using an ohmmeter.

The gap between the third and fourth band indicates the reading direction. This color code technique only works in fixed-resistance resistors.

However, you cannot find the resistance in variable resistance through the color code technique, you will need an ohmmeter to measure the resistance of variable resistors.

How to read color code of resistor

Chart below shows how to calculate the resistance of your resistor when you have no ohmmeter, and the chart given by the manufacturer has gone away.

These color stripes on resistors are called bands, and we have multiple bands on resistors like three, four, five, and six bands.

What is a tolerance band?

Resistors have tolerance band coated on their body, and it represents the variation in the resistance. Most precision resistors have a very low tolerance. Mostly, low tolerance resistors used in military, medical equipment, space to get better reliability.

Let’s say we have a resistor of 1 kΩ with a tolerance of ±5 then its actual resistance of the resistor is somewhere between 950Ω to 1050Ω.If there is a gold band coated at the right, then it means a resistor has 5% tolerance, silver has 10%, and if there is no band, then 20%.

Four bands resistor

Gaps between the bands are just to make reading easy, and you have to read it from left to right. First, two-bands are the significant figures, the third band is the multiplier, and the fourth band is the tolerance band.

If you read the color-coding of four band resistors from the picture. We have a red and green band; red has a significant figure of 2 and green has 5. The third band shows the multiplier, which is “1K,” then we will multiply the 1k with 2 and 5 that is 25k, and the fourth band indicates the tolerance of the resistor.

Five band resistor

First three bands of the resistor show the significant figure, the fourth one is the multiplier, and the fifth represents the tolerance band.

Six band resistor

Resistors with six bands have high precision, and the sixth band uses the temperature coefficient (ppm/K), and brown is the most common color for the sixth.

  1. 1st Band (orange) represents the significant number that is 3.
  2. 2nd Band (red) represents the significant number that is 2.
  3. 3rd Band (brown) represents the significant number that is 1.
  4. 4th Band represents the multiplier that is 10.
  5. 5th Band represents the tolerance band.
  6. 6th Band represents the temperature coefficient.

Shown example: 321*10= 3210 Ω or 3.21k Ω

Questions regarding resistor color code

Metallic band; gold and silver, could never be on the left side. If it starts with the gold and silver. Keep that band onto the right side and read again from left to right.

Bands which are closed to each other or placed towards one end. Position them to the left and read it from left to right.

A lot of techniques are circulating on the internet to memorize the color coding sequence. This one is the easiest to remember the color coding sequence. You just need to remember a sentence “Bad Beer Rots Our Young Guts but Vodka Goes Well Get Some Now!”

You can also learn it by heart, but if you are mixing the colors, then you have an excellent opportunity to learn these colors by just remembering the sentence.

In short, active devices are those who are capable of delivering power to the circuit. On the other hand, passive devices are those who don’t deliver or incapable of delivering power to the circuit such as resistors, inductors and capacitors.

The measuring unit of resistance is ohms.

Examples

You might have understood the concept of how to read the color codes of resistors. Here are some examples you need to tell the resistance by just looking at the color codes printed on the resistors.

It might be a good practice of reading the color codes.

Calculate the resistance.

Answer

Brown: significant number (1)

Black: significant number (0)

Brown: multiplier (10)

Gold: tolerance ±510*10=100 Ω ±5 tolerance

Answer

Brown: significant number (1)

Black: significant number (0)

Orange significant number (3)

Red: multiplier (100)

Gold: tolerance ±5103*100=10.3 K Ω ±5 tolerance

Answer

Orange: significant number (3)

Red: significant number (2)

Brown: significant number (1)

Brown: multiplier (10) and Sixth band is tolerance band

Red: temperature coefficient 50ppm/K

321*10=3210 or 3.21K Ω ±1 50ppm/K

Power rating of resistor

The heat will produce when resistors having low resistance pass an excessive amount of current. You will also feel a little warm when you touch the top of the resistor. Manufacturers rarely quote the power rating of resistors. It is mentioned on the part list when high power is required.

P=V2 / R or  I2/R

  • P= power developed in watts
  • I= current through resistors in amps
  • R= resistance through resistors in ohms
  • V= voltage across resistors in volts

Schematic representation of resistor

  1. Resistor
  2. Variable resistor
  3. Potentiometer
  4.  IEC resistor symbol
1 Comment
  1. Bilal Ahmed says

    It’s such a wonderful knowledge about resistors.

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