m.j.college, jalgaon and electronics/f.y.bsc resistor.pdf · light dependent resistors (ldr): the...
TRANSCRIPT
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