How To Measure and Identify Resistor Using Multimeter & Color Codes?

How To Measure and Identify Resistor Using Multimeter & Color Codes? | integraudio.com

Resistors are passive two-terminal electrical components that implement electrical resistance as a circuit element. They are used to reduce current flow, voltage drop, or electrical noise and find applications in electronic devices such as motors, televisions, audio amplifiers, and other electronic equipment. Resistors are color-coded to make it easier to identify the resistor’s value by looking at the color bands on the resistor.

If you are trying to repair an electronic device or troubleshoot a circuit, then you may be asking:

How do I identify and test a resistor using a multimeter?

You can quickly identify a resistor by the color bands printed on it. The first two or three bands represent a numerical value, while the rest indicate the resistor’s tolerance. Resistors are one of the most important components in an electronic circuit. 

There are several different types of resistors to choose from, all with specific applications.

Knowing how to test a resistor using a multimeter is critical for anyone working on electronic circuit boards, especially if you want to replace electronic components in your device, such as installing an amplifier into your car or building electric guitars. This article will explain how to test a resistor using a multimeter and identify the ohms rating using color codes.

How To Identify A Resistor Using Color Codes?

Three main colors are used in resistor color codes to indicate their value. Resistors are usually identifiable on a schematic by their color stripes. Each color represents a number that can be converted back into a resistance value using a simple formula.

The different colors on a resistor are identified as follows:

  • Black – B
  • Brown – B
  • Red – R
  • Orange – O
  • Yellow – Y
  • Green – G
  • Blue – B
  • Violet – V
  • Grey – G
  • White – W
Band Colors 1st Digit 2nd Digit 3rd Digit Multiplier Tolerance Temperature Coefficient
Black 0 0 0 1 Ohm 250 ppm/K
Brown 1 1 1 10 Ohm ±1% % 100 ppm/K
Red 2 2 2 100 Ohm ±2% % 50 ppm/K
Orange 3 3 3 1 k Ohm 15 ppm/K
Yellow 4 4 4 10 k Ohm ±0.5% 25 ppm/K
Blue 5 5 5 100 k Ohm ±1% 20 ppm/K
Green 6 6 6 1 M Ohm ± 0.1% 10 ppm/K
Violet 7 7 7 5 ppm/K
Grey 8 8 8 1 ppm/K
White 9 9 9
Gold 0.1 Ohm ± 5%
Silver 0.01 Ohm ±10%

How To Identify And Calculate A Three-Band Resistor Using Color Codes?

For a three-band resistor, there are only three color stripes. The first two bands represent the first two numbers of the resistor values, and the third band represents the multiplier.  For example, if a resistor has three bands arranged in the order red, black, and brown.

Then from the color codes, the red band represents 2, the black band represents 0, and the brown band which is the multiplier represents 10. Calculating the resistor value will mean 20 * 10 = 200 ohms. For a three-band resistor, there is no tolerance strip. The general value for the tolerance is given as ±20%. So, this will mean that the resistance of the resistor is 200 ±20%.

How To Identify And Calculate A Four-Band Resistor Using Color Code?

For a four-band resistor, the value can be calculated using the color code by identifying the values for each color band. The first two bands are the value of the resistance, the third band is the multiplier band, and the fourth band is the tolerance band. 

If you have a resistor with brown, black, red, and gold color bands arranged in order, the corresponding value of resistance will be calculated as follows:

Brown is the first band which is equivalent to 1
Black is the second band value which is equivalent to 0
Red is the multiplier band which is equal to 100
Gold is the tolerance band which is equal to ±5%
Therefore, the value of the resistance will be 10 X 100 = 1000±5%

How To Calculate A Five-Band Resistor Using Color Code?

For a five-band resistor, the first three color bands represent the three resistance values, the fourth band is the multiplier band, and the fifth band is the tolerance band. This type of resistor is found in components with high resistance values. 

If the five color bands are brown, black, orange, red, and gold, respectively, then the value of the resistance is calculated as follows

Brown is the first band which is 1
Black is the second band which is 0
Orange is the third band which is 3
Red is the multiplier band which is 100
Gold is the tolerance band which is ±5%
Calculating for the resistance, we have 103 X 100 = 10300±5%

How To Calculate A Six-Band Resistor Using Color Code?

A six-band resistor consists of the first three color bands representing the resistor values, the fourth color band representing the multiplier, the fifth color band representing the tolerance value, and the sixth color band representing the temperature coefficient.

Suppose the six colors in a resistor are brown, black, orange, red, gold, brown. Then, the resistance of the resistor will be calculated as follows:

Brown is the first band which is 1
Black is the second band which is 0
Orange is the third band which is 3
Red is the multiplier band which is 100
Gold is the tolerance band which is ±5%
Brown is the temperature coefficient which is 100 ppm/oC
The final value of the resistor is given as 103 X 100 = 10300±5% 100 ppm/oC

How To Test And Measure A Resistor Using A Multimeter?

There are two types of multimeters that you can use to test the resistance of your resistor. They are – digital and analog multimeters. Measuring the resistance value of a resistor follows the same principle whether you are using a digital or analog multimeter. 

The resistance is measured by placing the multimeter on the two probes of the resistor and passing a current through the resistor to determine the value of the resistance.

Source

How To Test A Resistor Using A Digital Multimeter?

As the name implies, the digital multimeter is much easier than the analog multimeter. Follow the steps below to measure the value of your resistor accurately using a digital multimeter.

  • Select the resistor you intend to measure and carefully estimate its resistance value.
  • Every multimeter has a socket for its probe. Insert the probes or wires into the socket and ensure it is properly fixed.
  • Put on the digital multimeter.
  • You will now have to select the resistance range according to the estimated value. Ensure the selected range is not too wide apart from the resistance value and is not too close. It should just be at a good enough range to get an accurate and precise measurement.
  • Use the probes on the digital multimeter to put on the two terminals of the resistor. This way, your measurement will be displayed on the screen of your digital multimeter.

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How To Test A Resistor Using An Analog Multimeter?

The analog multimeter is a bit technical when measuring the resistance of your resistor. Follow The steps below to measure your resistance accurately using an analog multimeter.

  • Select the resistor you intend to measure and estimate the value of the resistor.
  • Take the probes of the resistor and fit them into the sockets of your analog multimeter. Ensure it is properly fitted to avoid deflections when measuring.
  • Put on the meter and select the required range you intend to measure. The range should be selected based on the estimated value of the resistance. The value should not be too wide apart and shouldn’t be too close. It should be just okay to give the resistance an accurate and precise value.
  • Ensure you zero the meter. You can zero the analog multimeter by putting the terminal of the two probes together to cause a short circuit.
  • Make the measurement and ensure to read the values correctly.
  • Put off the multimeter and turn it into a high voltage range to avoid damage when measuring another resistor.

Source

Things To Note When Measuring Resistance Using A Multimeter

In measuring the resistance of a resistor in a circuit, there are certain precautions to note to ensure precise and safe measurement. Some of the precautions include:

  • Ensure the circuit is not connected to electricity or powered on before measuring the resistance.
  • Take measurements of the resistor when the components are not fixed or connected.
  • The capacitor in the circuit to be tested should be discharged.
  • Hold the resistor onto the probes closely because leakage can cause changes and fluctuations in the resistance value.

Using a multimeter to identify the value of the resistor you are working with is the easiest way to know the resistance of your electric component because in this case, you can read the resistance directly from your multimeter. There is no need to use your calculator and perform complex mathematical operations. Just connect the circuit using a test probe and finally, read the resistance value from the multimeter.

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