What is Color Ring Inductor? How to Read Inductor Color Code?

Ⅰ. What is color ring inductor?

A color ring inductor, also known as a color code inductor, is a fundamental electronic component that plays a crucial role in circuit design and electronic systems. These components work in conjunction with capacitors to create resonant and filter circuits, serving essential functions in modern electronics (Cogdell, 2021). Together with a capacitor, the inductance coil (color ring inductance) frequently creates a resonant and filter circuit in the circuit. The color ring inductor's main operating principle is charging and discharging, with rectification, oscillation, and other functions are thrown in for good measure. Color ring inductance is commonly used for signal quality control and circuit matching. The link between the ground and the power supply is, in general, an energy storage element.

The change in inductance of the color ring inductor is caused by a change in the external alternating power supply, therefore the color ring inductance has the property of preventing current changes in the  AC  circuit due to the objective impact. In other words, when the color ring inductor is connected to an  AC power supply, the magnetic field lines inside the color ring inductor will always vary with the alternating current, causing electromagnetic induction to occur. The color ring inductor refers to the electromotive force generated by the inductor's current changing.

Ⅱ. How does color ring inductor work?

Color ring inductors operate on the principle of electromagnetic induction, generating a magnetic field when subjected to varying current. This interaction between current and magnetic field is fundamental to the inductor's operation, creating self-inductance in any conductor carrying fluctuating current (Alexander & Sadiku, 2020).

Key characteristics include:

• Magnetic field generation

• Self-inductance properties

• Current regulation capabilities

The color ring inductor works because it generates a shifting magnetic field when an unstable current is passed through it, and this magnetic field affects the current. As a result, any conductor that passes an unstable current will fail. The current will be affected by the changing magnetic field, hence any conductor will have self-inductance. On the motherboard, there are a lot of copper-wound coils. Inductance is the name given to this coil. Magnetic core inductance and air-core inductance are the two basic types of inductance. In a similar vein, the huge inductance of the magnetic core inductance is frequently utilized in filter circuits, whereas the small inductance of the air core inductance is frequently employed in high-frequency circuits.

Ⅲ. What's the function of color ring inductor?

Only the unstable current can be used by the color ring inductance. It has the property that the voltage at both ends is proportional to the current running through it at the instantaneous rate of change (derivative). Because of its "self-inductance" inductance, the proportional coefficient operates. A shifting magnetic field is produced when an unstable current is passed, and this magnetic field affects the current. As a result, any conductor passing an unstable current will produce a fluctuating magnetic field that will be reversed in this scenario. As a result of the effect on the current, any conductor will have self-inductance.

Color ring inductors serve several critical functions:

• Current stabilization

• Energy storage

• Signal filtering

• Circuit matching

• Power supply decoupling

Color ring inductors are similar to color ring resistors in appearance. The inductance is usually marked with three or four colored bands. Color ring inductors or color code inductors are inductors that employ color rings to indicate inductance. The color ring inductor is made up of a coil and a magnetic core and serves as an energy storage and filtering device. The look of the color ring inductor in high-frequency electronic equipment has a layer of paint that works as insulation. The color ring inductor plays a role in the circuit that is similar to that of a transformer, which is utilized for signal conversion and transmission and is sometimes referred to as a transformer.

Ⅳ.  How to read inductor color code?

The color coding system follows standardized conventions similar to resistor color codes, allowing for quick identification of inductance values (Malik et al., 2019).

The numbers represented by the color of the color ring inductor: brown 1, red 2, orange 3, yellow 4, green 5, blue 6, purple 7, gray 8, white 9, black 0

The magnification represented by the color of the color ring inductor  : brown*10 (10^1), red*100 (10^2), orange*1K(10^3), yellow*10K(10^4), green*100K(10^5), blue*1M(10^6), purple*10M(10^7), gray*100M(10^8), white*1000M(10^9), black*1(10^0), gold* 0.1 (10^-1), silver 0.01 (10^-2)

The error level represented by the color of the color ring inductance: gold 5 [%], silver 10 [%], brown 1 [%], red 2 [%], green 0.5 [%], blue 0.25 [%], purple 0.1 [%] , Gray 0.05［%］, colorless

The basic unit of color ring inductance is "microhenry"

Take the four-ring inductor as an example:

How to read the four-ring inductor: the first 2 digits are valid digits, the third digit is the magnification, and the fourth digit is the error level.

For example:

The first ring: Brown——represents 1

The second ring: black-represents 0

The third ring: Red-represents 2 zeros, but the "2" in the third ring is not a "significant digit", but means the number of "zeros" added after the first two significant digits.

From this point of view, the inductance of this inductor should be 1000. What is the unit? In the color ring inductance, the default is "micro-sharing" (the basic unit of inductance, the symbol is uH).

The inductance of the above inductance is: 1000uH (102)

So, what does the fourth ring mean? The fourth ring represents the "precision" of the inductance, that is, the error of the sensed value. Gold represents an error of ±5%, and silver represents an error of ±10%.

Recognition sequence of color ring inductance

To arrange the order of the color circles, first, find the color circle that represents the inaccuracy. Gold, silver, and brown, particularly gold and silver rings, are the most widely utilized hues to indicate resistance faults. They are almost never used as the first ring of a resistance color ring. As a result, as long as the resistor has gold and silver rings, it can be presumed that this is the color ring resistance's last link.

Whether the brown ring represents the mistake mark's judgment. The brown ring is frequently used as an error ring, but it can also be used as a legitimate number ring, and it frequently appears in both the first and last rings at the same time, making it difficult to tell which is the first. In fact, the resistance of a five-color ring can be measured by the interval between the color rings: for example, the interval between the fifth ring and the fourth ring is bigger than the interval between the first ring and the second ring. The sequence of the color circle can be determined depending on this to make it wider.

If you can't figure out the first step, you'll need to take a closer look at the color circle. The second ring is the one that appears white, gray, purple, blue, green or yellow between the first and last second rings.

Points for Attention in Color Ring Inductance  Recognition

What are the key points of the color ring inductance identification method?

Note 1: Use ambient temperature

In the circuit, how does the color ring inductor heat up? The temperature of the color ring inductor is usually kept between minus 40 and 120 degrees Fahrenheit, although it cannot be too high or too low. When the temperature is high, the inductance begins to decrease. What makes this unique? The inductance of the color ring inductor will drop quickly if the temperature of the inductor surpasses 140 degrees, because the higher the inductor's usage temperature, the greater the influence of the inductor product, according to the majority of customers. Keep an eye on the circuit's temperature while it's in operation. At high temperatures, inductors cannot be utilized continually. This is something that should be kept in mind while using the product.

Note 2: Introduction to the reading method of color ring inductance

Introduction to the color ring inductor reading method: The color ring inductor is the same as the four rings' color ring resistance, although the inductance is significantly less accurate than the resistance. Carbon film resistance is typically around 5%. It's the same thing as defiance. If you have previous experience, you can return to the E24 resistance sequence list (1.0, 1.1, 1.2 to 9.1), as well as the inductance. The color ring inductance is the same as the four rings' color ring resistance, although the inductance is significantly less accurate than the resistance. The carbon sheet resistance is typically 5%, and the inductance is typically 10%. (the silver ring is the last ring). A frequent way is to place the silver ring on the far right. Numbers are represented by the first and second rings from the left, while the power of ten is represented by the third ring. Brown-black-brown-silver, for example, is a power of 10*10. The calculating unit is micro-Henry  (uH) (for reference, the unit after reading the color ring resistance is ohm), and silver denotes an accuracy of plus or minus 10%. The numbers are represented by the colors of the color circle: brown 1, red 2, orange 3, yellow 4, green 5, blue 6, purple 7, gray 8, white 9, black 0. The magnification represented by the color circle color: brown*10, red*100 , Orange*1K, yellow*10K, green*100K, blue*1M, purple*10M, gray*100M, white*1000M, black*1, gold*0.1, silver*0.01 The error level represented by the color ring color: gold 5 %, silver 10%, brown 1%, red 2%, green 0.5%, blue 0.25%, purple 0.1%, gray 0.05%, colorless 20%

Ⅴ.  How to measure the color ring inductance?

Use a multimeter to test the resistance of the color ring inductor

Inductors cannot be tested with ordinary analog multimeters since they lack special gear. We can only use this type of multimeter to basically measure the quality of inductors: use the analog multimeter's R1W gear to measure the inductor's resistance and measure it. If the measured resistance is, the inductor has been opened and damaged. If the measured resistance is, the inductor has been opened and damaged. If the resistance between the shell (shielding cover) of the oscillating inductor coil and each pin is not a particular resistance value or zero for an inductor with a metal shell (such as a center circumference), there is an issue with this inductor, 

The extra reason is that when testing inductors, the digital multimeter's range selection is critical. It's ideal to measure inductance in a range that's close to the nominal value; otherwise, the test result will be off by a lot.

Because the color ring inductor is a non-standard item, it's not as easy to spot as a resistor.  and some inductors don't have a label, it's usually essential to utilize the parameter label on the drawing to determine its inductance. It must be replaced with an inductor that has the same characteristics and properties as the original one when it is repaired.

How to measure the inductance of the color ring inductor?

An  LCR  tester, which can precisely and consistently measure inductance, can be used to determine it. If an  LCR measuring equipment is not available, the inductance and capacitance meter indicated in the diagram below can be used to determine the inductance.

Multimeter measuring color ring inductance is good or bad

The color ring inductor has a similar shape to the color ring resistance, but the two ends are pointed, the middle is large, and the point where the lead connects is gradually thinner; the resistance, on the other hand, is thick on both sides, then in the middle, and very uniform, and it is connected to the lead. The vertical cross-section is the location.

Color ring inductors typically have a green backdrop, whereas resistors typically have a brown, blue, or off-white background.

Set the pointer multimeter's switch to the Rx1 gear and connect the red and black test leads to any pin of the inductor to detect the inductor's quality. It can be split into three categories based on the measured resistance value. Determine the following scenarios:

①There is a short-circuit fault inside the tested coil or color code inductor.  and its resistance value is zero.

②The needle rotates, and the resistance value of the measured inductance is read. The diameter of the enameled wire used to wound the inductor and the number of turns has a direct relationship with the resistance value. It can be regarded as the measured winding or the measured resistance value as long as the resistance value can be measured. The inductance is very standard.

③There is no movement of the needle, and the recorded inductance resistance value is infinite, indicating an open circuit problem inside.

Matters needing attention in the use of  color ring inductors

1. The core and winding of inductance components are prone to changing inductance as the temperature rises. Please keep in mind that the body temperature must be within the specified range.

2. After the current flows through the inductor's winding, an electromagnetic field can easily form. When assembling the components, make sure that adjacent inductors are spaced apart or that the winding groups are at right angles to each other to reduce mutual induction.

3. Gap capacitance will be formed between the windings of each layer of the inductor.  especially the multi-turn thin wire, causing high-frequency signal bypass and reducing the inductor's actual filtering function.

4. To acquire accurate data while measuring the inductance and Q values with the meter, the test lead should be as close to the component.

References:

Alexander, C. K., & Sadiku, M. N. O. (2020). Fundamentals of Electric Circuits (7th ed.). McGraw-Hill Education.
https://www.mheducation.com/highered/product/fundamentals-electric-circuits-alexander-sadiku/M9781260226416.html

Cogdell, J. R. (2021). Foundations of Electronic Circuits and Devices (5th ed.). Oxford University Press.
https://global.oup.com/academic/product/foundations-of-electronics-9780190855796

Malik, N., Morris, J. E., & Digite, K. (2019). Electronic Components and Technology (4th ed.). CRC Press.
https://www.routledge.com/Electronic-Components-and-Technology/Malik-Morris-Digite/p/book/9780367657834

National Institute of Standards and Technology. (2022). Electronics and Electrical Engineering Laboratory: Electromagnetic Components and Measurements.
https://www.nist.gov/electronics-and-electrical-engineering