RESISTOR

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TABLE OF CONTENTS:

II . TYPES OF RESISTOR

III. RESISTOR COLOR CODING

I . RESISTOR

RESISTOR

An Electronic components that are designed to have a specific amount of resistance.

Are the most common in electronic circuits

Controls the current flow and voltage

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HIGH FREQUENCY EFFECTS ON RESISTOR

• The effective resistance value of a resistor may be changed when it is subjected to alternating voltage. Not only that the value of resistance varies with variation of frequency of supply voltage. This change of resistance with frequency is called BOELLA EFFECT.• High frequency effect on resistor depends upon its constructional

feature. The impedance of wire-wound resistor increases with frequency. On the other hand composition resistor reduces its impedance with increasing frequency.

• The high frequency response of a resistor may also depend up to some extend on diameter of the resistor. It is seen that smaller diameter resistor has better frequency response.

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VOLTAGE COEFFICIENT OF RESISTANCE

• Voltage Coefficient of Resistance (VCR) is a measure of the stability of the resistor with respect to changes in voltage.

• Voltage coefficient, measured in ppm/V, is negative for most materials. Voltage coefficient is generally measured between 10% and full rated voltage.

• Voltage coefficient (VC) is usually experienced with film resistors as the electrostatic field generated by the voltage tends to align polarized molecules in the resistance film, much in the same way as a capacitor dielectric.

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NOISE OF A RESISTOR

• Noise in a resistor is caused by it’s applied voltage, it’s physical dimensions, and materials by which it is made of. The noise includes Johnson noise, noise due to flow of current, noise due to cracked bodies, and noise due to loosen end caps and leads of the resistor. For variable resistors the noise can also be caused by the jumping of a moving contact over turns and by an imperfect electrical path between the contact and resistance element.

• Johnson noise is thermal noise. This noise depends upon temperature but does not depend upon frequencies. As this noise is same for all frequencies it is referred as “white noise”.

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POWER RATING OF RESISTOR

• The power rating of resistor is defined as the maximum power that a resistor can dissipate in form of heat to maintain the temperature within maximum allowable limit. How much power a resistor will dissipate depends upon material, dimensions, voltage rating, maximum temperature limit of the resistor and ambient temperature.

• A resistor must be operated within a temperature limit so that there should not be any permanent damage due high temperature.

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VOLTAGE RATING OF RESISTOR

• This rating is defined as the maximum voltage that can be applied across a resistor due to which power dissipation will be within its allowable limit. Actually voltage rating of resistor is related to the power rating.

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EVALUATION

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QUESTION:

1. DEFINED AS THE MAXIMUM VOLTAGE THAT CAN BE APPLIED ACROSS A RESISTOR DUE TO WHICH POWER DISSIPATION WILL BE WITHIN ITS ALLOWABLE LIMIT.

A. NOISE

B. VOLTAGE RATING

C. HIGH FREQUENCY

EXCELLENT!!!

GENIUS

PROCEED

QUESTION:2. IT IS CAUSED BY IT’S APPLIED VOLTAGE, IT’S PHYSICAL DIMENSIONS, AND MATERIALS BY WHICH IT IS MADE OF.

A. VOLTAGE COEFFICIENT

B. NOISE

C. POWER RATING

EXCELLENT!!!

GENIUS

PROCEED

QUESTION:

3. IT IS A MEASURE OF THE STABILITY OF THE RESISTOR WITH RESPECT TO CHANGES IN VOLTAGE.

A. VOLTAGE COEFFICIENT

B. POWER RATING

C. VOLTAGE RATING

EXCELLENT!!!

GENIUS

TYPES OF RESISTORS• Resistors can be classified on various types based on various

factors. Some of the classification of resistors are:

Based on Conductive properties of Resistor:1. Linear Resistor:

A linear resistor is the type of resistor whose resistance remains constant with increase in the potential difference or voltage applied to it.2. Non linear resistor:

Non Linear Resistor are those types of resistors in which the current passed through it is not exactly directly proportional to the Potential Difference applied to it. These types of resistors have non linear V-I characteristics and does not strictly follows ohm’s law. NEXT

BASED ON RESISTOR’S VALUE:

1. Fixed Value Resistor:Fixed value resistor are those types of resistors whose value

is fixed already while manufacturing and cannot be changed during it’s usage.

2. Variable Resistor or Potentiometer :Variables resistors or Potentiometers are those types of

resistors whose value can be changed during it’s usage. These types of resistor usually contains a shaft which can be rotated or moved by hand or a screw driver to change it’s value in between a fixed range for example 0 Kilo Ohms to 20 Kilo Ohms.

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3. Package resistor:These types of resistor which contains a package that

contains two or more resistors inside it. It may have many terminals among the available terminals or can also be used as an resistor array for various purposes.

Based On Composition:

1. Carbon Deposition:The resistor which is made by depositing a thin layer of

carbon around a ceramic rod is called Carbon Deposition resistor. They are made by heating a ceramic rod inside a flask of methane and depositing the carbon around it by using Glass Cracking process. The value of resistor is determined by the amount of carbon deposited around the ceramic rod.

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2. Carbon Composition:These types of resistors are made by a composition of

Carbon Particles which are hold together by a binding resign. The proportion of carbon particles and resign used determines the value of the resistor. At both ends of the composition a Metal Cap with a small rod of tin is attached to solder it or use it in circuits , then the whole package is enclosed in a plastic case to prevent moisture and reaction with air.

These types of resistors normally produces noise in circuit due to electron passing through one carbon particle to another , thus these types or resistors are not used in critical circuits although they are cheap.

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3. High Voltage Ink Film:

These types of resistors are made by coating a special resistive ink in a helical band above a ceramic base. These resistors can withstand very high voltage of up to one thousands of kilo voltages and usually have high resistance too ranging from on kilo ohms to one hundred thousand mega ohms.

4. Metal Film:Metal film resistors are made by depositing vaporized metal

in vacuum on a ceramic core rod. these types of resistors are very reliable , have high tolerance and also have high temperature coefficient. These types of resistors are costlier compared to other but are used in critical systems.

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5. Metal Glaze:Metal Glaze resistors are made up of glass and metal

which is mixed and applied as a thick films to a ceramic substrate and then fired to form a film.

6. Wire Wound:Wire wound resistor are made by winding a metal wire

around a ceramic core. The metal wire is an alloy of various metals based on the characteristics and resistance of the resistor required. These types of resistor have high stability and can also withstand high powers but are usually bulkier compared to other types of resistors.

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7. Ceramic Metal:These types of resistor are made by firing certain metals blended with ceramics on a ceramic substrate. The proportion of the mixture in the blended ceramic and metal determines the value of the resistor. These type of resistors are very stable and also have accurate resistance. These types of resistors are mostly used as Surface Mount type resistor for using in SMD PCB.

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EVALUATION

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QUESTION: 1. THE TYPE OF RESISTOR WHOSE RESISTANCE REMAINS CONSTANT WITH INCREASE IN THE POTENTIAL DIFFERENCE OR VOLTAGE APPLIED TO IT.

A. LINEAR RESISTOR

B. NON LINEAR RESISTOR

C. CARBON COMPOSITION

EXCELLENT!!!

GENIUS

PROCEED

QUESTION:2. THE TYPE OF COMPOSITION RESISTOR THAT ARE MADE BY DEPOSITING VAPORIZED METAL IN VACUUM ON A CERAMIC CORE ROD.

A. CERAMIC METAL

B. METAL FILM

C. METAL GLAZE

EXCELLENT!!!

GENIUS

PROCEED

QUESTION:

3. THESE TYPES OF RESISTOR USUALLY CONTAINS A SHAFT WHICH CAN BE ROTATED OR MOVED BY HAND OR A SCREW DRIVER TO CHANGE IT’S VALUE IN BETWEEN A FIXED RANGE FOR EXAMPLE 0 KILO OHMS TO 20 KILO OHMS.

A. FIXED RESISTOR

B. VARIABLE RESISTOR/POTENTIOMETER

C. PACKAGE RESISTOR

EXCELLENT!!!

GENIUS

RESISTOR COLOR CODING• Manufacturers typically use a color band system in order to

identify the nominal resistance and tolerance of a resistor.

Resistor color coding chart

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4-Band Resistors

1. Resistors with 5% and 10% Tolerance will have 4-bands

2.Convert nominal value to ohms ()

3.1st digit (from left to right) of nominal value = 1st color band

4.2nd digit of nominal value = 2nd band

5.Number of zeros remaining = 3rd (multiplier) band

6.Tolerance = 4th band

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5-Band Resistors

1.Resistors with 1% and 2% Tolerance will have 5-bands

2.Convert nominal value to ohms ()

3.1st digit (from left to right) of nominal value = 1st color band

4.2nd digit of nominal value = 2nd band

5.3rd digit of nominal value = 3rd band

6.Number of zeros remaining = 4th (multiplier) band

7.Tolerance = 5th band

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EXAMPLES OF 4-BAND & 5-BAND RESISTOR

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EVALUATION

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QUESTION:

1. WHAT IS VALUE OF THIS RESISTOR?

A.360 K Ω±10%

B.2.4 M Ω±10%

C.2.6 M Ω±10%

GENIUS

EXCELLENT!!!

PROCEED

QUESTION:

2. A SYSTEM USED BY MANUFACTURERS IN ORDER TO IDENTIFY THE NOMINAL RESISTANCE AND TOLERANCE OF A RESISTOR.

A. RESISTOR COLOR CODE

B. RESISTOR TOLERANCE

C. 4- BAND RESISTOR

EXCELLENT!!!

GENIUS

PROCEED

QUESTION:

3. A TYPE OF BAND RESISTOR WITH 1% AND 2% TOLERANCE

A. 4-BAND RESISTOR

B. 5-BAND RESISTOR

C. COLOR SYSTEM BAND

EXCELLENT!!!

GENIUS

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