Introduction to Basic Component.

Mr. Kishor.S.Bonde

Department of Physics

Moolji Jaitha College, Jalgaon. (MS)

M.J.COLLEGE, JALGAONF.Y.BSc Electronics

Sub:- Analog Electronics-I

• Resistor

• Capacitor

• Relay

• Switches

What is Resistor?Resistor is circuit element which opposes the flow of

current through it. The constructed element of resistive

material is called resistor.It is two terminal passive components, which obeys ohm law. i.e. The potential difference across two terminals of resistance is directly proportional to current flowing through the resistor.V = IR. The unit of resistance is (ohm). The large units are K, M.

Types of Resistance: –Resistors are classified into two groups

1. Fixed Resistor: –

Fixed Resistors are two terminal components. The resistance between two

terminals remains fairly constant.

The symbol of fixed resistor is as follows.

2. Variable Resistor: –

Variable resistors having Three terminals, Two terminals are fixed where

as third one is variable. The resistance between fixed & variable terminals

can be changed using shaft or slider etc.

The symbol of variable resistor is as follows.

1.Fixed Resistor: –Three basic types of fixed resistors are available into market.1.Carbon composition resistor.2.film resistor 3.wire wound resistor

1.Carbon Composition Resistor

Color bands are painted on resistance to indicate value of resistance. Specification: –

Resistance Range 1 TO 20m

Tolerance 5% to 20%

Temp Range – 55o C to 150o

Power Ratings

Working Voltage up to 750 V.

These resistors are cheap, small in size & having low induction applications of resistors are in general purpose electronic equipments & high voltage circuits.

At higher temperature it introduce noise in signal and stability is affected.

cap

Terminal (lead)

Carbon composition rod.Colour coding

1 1 11 2 W .

8 4 2W , W , W , W ,

2.Film ResistorThere are two types of film resistor

i)Metal film Resistors: –Specification: –Resistance Range 1 to 107 k.Temp. Coeff of Resistance 1000 ppm/o C. Stability < 3 %Tolerance < 2 %Maximum Voltageup to 500 V.Working temperature – 40o to + 150o C.

These resistors having better stability than carbon composition resistor, small in size, close tolerance values, but do not withstand to higher load current.

ii). Carbon Film Resistors:Specification: –Resistance Range 1 to 107 k.Temp. Coeff of Resistance 1000 ppm/o C. Stability < 3 %Tolerance < 2 %Maximum Voltageup to 500 V.Working temperature – 40o to + 150o C.

These resistors having better stability than carbon composition resistor, small in size, close tolerance values, but do not withstand to higher load current.

Ceramic rod. (substrate)

lead

Metal thin film

epoxy coating

Ceramic rod. (substrate)

lead

Carbon film

epoxy coating

3.Wire Wound Resistor

11

111111

Specification: – Resistance Range 0.1 to few ohms. Tolerance > 0.5 % Temp coeff 5 ppm/o C. Working voltage < 300 V.

2.Variable Resistor Rheostat

Potentiometer

Thermistors

Light dependent Resistors (LDR)

Varistors (Voltage dependant Resistors)

Rheostat

Specification: –

Resistance Range few ohms to 500 .

Current Capacity 0.1 to 20 Amp.

Slider

Variable

terminal

Fix terminals

Fig. 1.10: Rheostat

Potentiometer Resistive material coated

over substrate.

Wiper / Slider

Preset potentiometer

Specification: –

•Resistance Range 100 to 20 M.

•Power Ratings Maxm 0.6 w.

•Maxm Operating temp 70o C.

•Temp coeff 1200 ppm/ o C .

•Tolerance 20%.

Advantages: –

•Small in size.

•Cheaper than potentiometer.

Disadvantages: –

•Poor stability.

Thermistors

There are two types of thermistors are available into market, the resistance value of thermistor varies with temperature.

NTC Negative temperature coefficient. PTC Positive temperature coefficient

Symbol of ThermistorBead Type disc

Washer Type Rod type

T

Light dependent Resistors (LDR): The resistance of LDR depends upon the intensity of light

incident on it. Hence it is also called as photo resistors, or light dependent resistor.

LDR having very high resistance more than 100 k, in dark called as dark resistance, when illuminated by light, resistance decreases as intensity of light increases.

The photo conductive material such as cadmium selenide, cadmium sulphate lead sulphide or thalium sulphide is coated in zigzag line.

Symbol of LDR

LDR

Resistance in K Ω

Light intensity lm/m2

Varistors (Voltage dependant Resistors): –Resistance of these resistor depends upon applied voltage. These

resistances having large negative voltage coefficient. When voltage applied across varistors exceed the certain limit, the resistance decreases abruptly, and large current flow thought it. Such a kind of varistors are used to protect electronic circuit from voltage spike or surge. These varistor are used in spike protector circuit. Telephone circuit. Electronic ballast for tube light etc.

There are two types of varistors are available into market. Silicon carbide Varistors:- In which I-V characteristics changes slowly. Metal oxide varistors (MOV):- In which I-V characteristics change abruptly.

Symbols of Metal oxide varistor