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  • P-TYPE : Trivalent impurities (3 valence electrons)
    • Aluminium, boron, gallium and indium.
  • N-TYPE : Pentavalent impurities (5 valence electrons)
    • antimony, arsenic, bismuth and phosphorus.


  • Atom consist of the three stage of the particles namely electron (outer most of the orbit), and clustered neutron and proton.
  • Atoms are very minute part in the element,
  • We cannot visible the atom, the radius of the atom is 1A0=10-10m.
Name Symbol Mass(atomic mass unit) Normal mass(a.m.u)
Electron E -1 5.4000000000000001E-4 0
Proton P 1 1.0072700000000001 1
Nutron N 0 1.00867 1

Coulomb’s law

  1. The force between two charged bodies was studied by Coulomb in 1785.
  2. Coulomb’s law states that the force of attraction or repulsion between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. The direction of forces is along the line joining the two point charges. Let q1 and q2 be two point charges placed in air or vacuum at a distance r apart. Then, according to Coulomb’s law,

F αq1 q2/r2

orF = k×q1 q2/r2

where k is a constant of proportionality. In air or vacuum,

k =1/4πε0, where εo is the permittivity of free space (i.e., vacuum) value of ε0 is 8.854 × 10-12 C2 N-1 m-2.

Ohm’s Law (1827)

  1. George Simon Ohm established the relationship between potential difference and current, which is known as Ohm’s law.
  2. At a constant temperature, the steady current flowing through a conductor is directly proportional to the potential difference between the two ends of the conductor.

(i.e) I α V

Kirchhoff first law (current law)

Kirchhoff current law states that the algebraic sum of the currents meeting at any junction in 7 a circuit is zero.

Kirchoff’s second law (voltage law)

Kirchoff’s voltage law states that the algebraic sum of the

products of resistance and current in each part of any closed circuit is equal to the algebraic sum of the emf’s in that closed circuit. This law is a consequence of conservation of energy.


Resistance of a conductor is defined as the ratio of potential difference across the conductor to the current flowing through it. The unit of resistance is ohm (Ω)


Resistance – The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor. The inverse quantity is electrical conductance, and is the ease with which an electric current passes.

Any conductor’s resistance depends upon the following things

  1. Length of the conductor (L).
  2. Specific resistance of the nature material (Rho).
  3. Cross sectional area of the conductor(A).

Length Directly is Proportional to Resistance

R ∝ L

The resistance is directly proportional to the length

If the conductor length is longer then resistance is high so current flow is less.

Cross Sectional Area is inversely Proportional Resistance

R ∝ 1/A (or) R ∝ A-1.

Circular Conductor

Rectangular Conductor

Specific Resistance of the materials

The specific resistance of the material of a wire is determined by knowing the resistance (P), radius (r) and length (L) of the wire using the expression ρ =Pπr/L

Material ρ (Ωm) at 20°C σ (S/m) at 20°C Temperature coefficient (1/°C) x10^-3
Silver 1.59×10−8 6.30×107 3.8
Copper 1.68×10−8 5.96×107 3.9
Gold 2.44×10−8 4.10×107 3.4
Aluminum 2.82×10−8 3.5×107 3.9
Tungsten 5.60×10−8 1.79×107 4.5
Zinc 5.90×10−8 1.69×107 3.7
Nickel 6.99×10−8 1.43×107 6
Lithium 9.28×10−8 1.08×107 6
Iron 1.0×10−7 1.00×107 5
Platinum 1.06×10−7 9.43×106 3.9
Tin 1.09×10−7 9.17×106 4.5
Lead 2.2×10−7 4.55×106 3.9
Manganin 4.82×10−7 2.07×106 2E-3
Constantan 4.9×10−7 2.04×106 8.0000000000000002E-3
Mercury 9.8×10−7 1.02×106 0.9
Nichrome 1.10×10−6 9.09×105 0.4
Carbon (amorphous) 5×10−4 to 8×10−4 1.25 to 2×103 -0.5
substance Nature Resistivity(ρΩm)
1 Silver Conductor 1.6×10-8
2 Gold Conductor
3 Copper Good conductor 1.7×10-8
4 Aluminium Good conductor 2.7×10-8
5 Iron Conductor 10×10-8
6 Steel Conductor
7 Brass Conductor
8 bronze Conductor
9 Mercury Conductor
10 Dirty water(salt water) Conductor
11 graphite Conductor
12 tungsten 5.5×10-8
13 Germanium Semiconductor (0.40)or (0.6Ωm)
14 Silicon semiconductor 2300
15 Glass Insulator 1010– 1014
16 neoprene Insulator
17 Wood Insulator 108-1011
18 rupper Insulator 1013-1016
19 Oil Insulator
20 Fiber glass Insulator
21 (Dry)cotton Insulator
22 (dry)wood Insulator
23 Air Insulator
24 Plastic Insulator
25 Pure water Insulator
26 Quqrtz Insulator 1013
27 Teflon Insulator
28 Nichrome Resistance material 10-4 Ωm


Example 1:

Copper material ρ (of copper) = 1.7 x 10-8 Ωm (17 E-9 or 17 EXP-9 when entering it into your calculator in Standard Form, depending on which model you use), L (Length of cable) = 7m and d (Diameter of cable) = 0.5mm(500 E-6 or 500 EXP-6 metres in Standard Form. so Find the resistance??


  • A (Cross Sectional Area of cable in square metres) = π(d/22) = 3.142 x ((500 EXP-6/2)2) = 196.4 EXP-9m2
  • Therefore R = (ρL) / A = (17 EXP-9 x 7) / 196.4 EXP-9 = 605mΩ

Example 2 :

A wire 12m long has a resistance of 1.5 Ω. What will be the resistance of 16m of the same wire?

Answer : 2 Ω

Example 3

A sample of copper wire of 0.2mm radius has a length of 5m. If the resistivity of the copper is 1.7 x 10-8, what would be the resistance of the wire?

Answer : 0.676Ω

Example 4

What is the resistance of 100m of copper wire, having a diameter of 1.024mm?

Ans : 2.06Ω

Example 5

The resistance of a 50m length of wire is found to be 0.83 ohms. Its diameter is 1.15mm. What is its resistivity and from what metal is it most probably made?

Ans : 1.72 x 10-8 copper

Example 6

What is the length of a copper wire having a radius of 0.25mm if its resistance is found to be 0.2 Ω?

Ans :

See Also

  • Resistor

Reference Websites


The reciprocal of resistance is conductance. Its unit ismho (Ω–1)


Electrons flow in a conductor

Eg: water flow in a pipe line.

  • 1amps= 6.25*1018=(6,250,000,000,000,000,000) electrons/second,


We define voltage as the amount of potential energy between two points on a circuit. One point has more charge than another. This difference in charge between the two points is called voltage. It is measured in volts, which, technically, is the potential energy difference between two points that will impart one joule of energy per coulomb of charge that passes through it (don’t panic if this makes no sense, all will be explained). The unit “volt” is named after the Italian physicist Alessandro Volta who invented what is considered the first chemical battery. Voltage is represented in equations and schematics by the letter “V”.

When describing voltage, current, and resistance, a common analogy is a water tank. In this analogy, charge is represented by the water amount, voltage is represented by the water pressure, and current is represented by the water flow. So for this analogy, remember:

  • Water = Charge
  • Pressure = Voltage
  • Flow = Current

Consider a water tank at a certain height above the ground. At the bottom of this tank there is a hose.

Voltage, Current, Resistance, and Ohm’s Law

Ohm’s Law


  • V = Voltage in volts
  • I = Current in amps
  • R = Resistance in ohms

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Michael Faraday (1791 – 1867)

A great experimentalism and popularize of science. He is most famous for his work on magnetic induction, but also did fundamental work related to electrolysis He worked at the Royal Institution (one of the first scientific research institutes) and established the Christmas Lectures on science for young people which are still running.

  • A capacitor consists of two conducting plates separated by an insulating medium,
  • The capacitor can store electric charges, in the form of voltage in electric field,
  • The capacitor blocks direct current,
  • The capacitor opposes any sudden change of voltage applied to it,
  • Capacitor only allows the Alternating current,
  • Capacitor makes the time delay
  • C=Ԑ o Ԑr A / d farad A=area of each plate in m2,
  • d=distance between the plates in meter, Ԑr =relative dielectric constant(permittivity).
  • Ԑ o=dielectric constant(permittivity)of free space,

Capacitance Units

Prefix Name Abbreviation Weight Equivalent Farads

Picofarad pF 10-12 0.000000000001 F

Nanofarad nF 10-9 0.000000001 F

Microfarad µF 10-6 0.000001 F

Milifarad mF 10-3 0.001 F

Kilofarad kF 103 1000 F

How a Capacitor Works

Charging and Discharging

Calculating Charge, Voltage, and Current

Calculating Voltage

Calculating Current

General Classification

  • Filter capacitor
  • Storage capacitor

Type of Capacitor

  • Fixed capacitor
  • Variable capacitor
Fixed Capacitor
  • Electrolytic capacitors.

o Polarized electrolytic capacitor

o Non polarized electrolytic capacitor

  • Aluminium type
  • Tantalum type
  • Non-electrolytic capacitors. (it has no polarity & colour coding)

o Ceramic capacitor

  • Disc capacitor
  • Tubular capacitor
  • Monolithic capacitor
  • Barrier level capacitor

o Plastic capacitor

  • Polystyre capacitor
  • Polyster capacitor
  • Polycarbonate capacitor
  • Mica capacitor

o Stacked mica capacitor

o Silvered mica capacitor

  • Paper capacitor

o Impregnated paper capacitor

o Metalized paper capacitor

Variable Capacitor (variable capacitor also called “gung”)
  • Ceramic variable capacitor
  • Plastic variable capacitor
  • Glass variable capacitor
  • Air variable capacitor

Capacitors in Series/Parallel

Energy Storage and Supply

Battery or Capacitor?

Battery Capacitor

Capacity ✓

Energy Density ✓

Charge/Discharge Rate ✓

Life Span ✓

Capacitor use

  • electrolytic capacitors: used as filter in a power supply, time constant circuits, bypass, coupling/decoupling, smoothing and power electronics application.
  • Non polarized electrolytic capacitor: used in applications such as AC motor starting, cross over networks and large pulse signals.
  • Ceramic capacitor: used as bypass capacitor and used in decoupling applications, frequency discriminators and biasing applications.
  • Tubular capacitor: used as isolate the antennas in receiver
  • Polystyrene capacitor: used in coupling, resonant and measuring circuits.
  • Polyester capacitor: used for coupling/decoupling applications, and also in power electronics.
  • Poly carbonate capacitor: used in dc application.
  • Mica capacitor: used as coupling capacitors at high frequency, in radio transmitters, measuring circuits, bypass circuits and RF resonant circuits
  • VARIABLE CAPACITOR- (variable capacitor also called “gung”) used in tuning circuits of communication receivers, transmitters and in oscillator.

o 1.Every circuit has must have the capacitor in the first stage,

o 2.capacitor makes the continuous current flow in the circuit,

o 3.variable capacitors are used in frequency turning in TV application.

o *after shutdown the power the capacitor stores the electric signal and it gives to the micro controller


  • TV1.

o Channel

o Volume

o Brightness.

Reference Website

Inductor (Joseph Henry (1797 – 1878)

Born in upstate New York he worked on electromagnetism and inductance in Albany and Princeton. Was appointed the first Secretary of the Smithsonian Institution in Washington in 1864

  • An inductor is a coil of wound on a core.
  • An inductor opposes the sudden variation of current.
  • an inductor stores the energy in the form of current in magnetic field.
  • the coil blocks DC voltage.
  • an inductor allows the Direct current
  • L=µ o µr A N2/l Henry
  • l=length of the core,
  • µ o=permeability of free space,
  • µr=relative permeability of the core material,
  • A=area of cross-section of the coil, N=length of the core,

Types of Inductors:

  • Fixed Inductors
  • Air Core Inductors
  • Iron Core Inductors
  • Ferrite Core Inductors
  • Variable Inductors
  • Movable Core Inductors
  • Tapped Inductors

Uses of Inductos

  • Iron core inductor
    • used in low frequency applications such as filter circuits in power supplies, chokes in fluorescent tubes or as a reactive element in ac circuits.
  • Ferrite Core Inductor
    • used in RF chokes for supply decoupling purpose
    • switching regulated type dc power supplies
    • various type of filters used in communication equipment’s
  • Ferrite core variable inductor
    • used in tuned circuits, it required to vary the inductance from a minimum value to a maximum value.

Application of Inductors

  • chokes for supply decoupling purposes.
  • switching regulated type dc power supplies.
  • various type of filters used in communication equipment


  • Conduct electricity (Electrons) easily in one direction
  • Two lead semiconductor
  • Diodes are made by Silicon [mostly], Selenium and germanium [Sometimes]
  • A PN-junction diode is formed by joining together n-type and p-type silicon.
  • In practice, as the n-type Si crystal is being grown, the process is abruptly altered to grow p-type Si crystal. Finally, a glass or plastic coating is placed around the joined crystal.
  • The p-side is called anode and the n-side is called cathode.
  • When the anode and cathode of a PN-junction diode are connected to external voltage such that the potential at anode is higher than the potential at cathode, the diode is said to be forward biased.
  • –In a forward-biased diode current is allowed to flow through the device.
  • •When potential at anode is smaller than the potential at cathode, the diode is said to be reverse biased. In a reverse-biased diode current is blocked.
  • + – + –

Water Analogy of Diodes

Various Diodes

  • Avalanche Diode
  • Constant Current Diode
  • Crystal Diode
  • Gunn Diode
  • LASER Diode
  • Light Emitting Diode(LED)
  • Photo-Diode
  • PIN Diode
  • Shockley Diode
  • Step Recovery Diode
  • Super Barrier Diode
  • Transient Voltage Suppression Diode (TVS)
  • Tunnel Diode
  • Thermal Diode
  • Vacuum Diode
  • Varactor Diode (Varicap)
  • Zener Diode


  • Types
    • PNP
    • NPN

BJT (bipolar Junction Transistor)

  • Aplication
    • DC to AC Concverter
    • Induction Motor driver
    • UPS
    • Chopper



  • Electronic filters are circuits, which perform, signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both.
  • Types
    • High pass filter
    • Low pass filter
    • Band-pass filter
    • Band stop filter

First order RC-filter (high/low pass filter)

  • The cut-off frequency is defined as the frequency at which the voltage at the output of the filter is 3dB below the input. In other words the output signal is 70.7% or 1/sqrt(2) below the input signal.
  • For a first order RC-filter the cut-off frequency (fc) is calculated as follows:
  • R1 * C1 = 1/ω = 1/ (2 π fc)
  • The time constant ω is equivalent to 2 π fc. Engineers prefer to use fc while many scientists use ω.a

LC Filter

  • Low pass- π filters
  • High Pass T Filter

Filters Type:

  • Capacitor filter
  • Choke input filter
  • Capacitor input filter or π filter

Reference websites

  • https://en.wikipedia.org/wiki/Electronic_filter
  • http://www.tuxgraphics.org/toolbox/circuit-design-calculator.html

What is Oscillator?

  • Oscillator is a heartbeat of every microcontroller design.

Types of Transistor oscillators

  • Tuned collector oscillator
  • Colpitt’s oscillator
  • Hartley oscillator
  • Phase shift oscillator
  • Wein bridge oscillator
  • Crystal oscillator
    • Crystal Oscillator is used for demand precise timing over a wide temperature range.

Oscillator for Microcontroller and Microprocessor

  • Internal
    • Usually (as far as i know, always) a resistor capacitor circuit.
    • Phase- locked loop for frequency multiplication
  • External
    • CMOS clock
    • Crystal
    • Ceramic resonator
    • Resistor-capacitor,
    • capacitor only

Quartz and ceramic oscillator

  • CL-total = ((CL1* CL2)/ CL1+CL2) + Cp
  • Cp – Parasitic capacitance
  • CL1, CL2 – Load Capacitance



  • Pressure Transducers
  • Vacuum pressure Transducers
  • Melt Pressure Transducers
  • submersible Transducers
  • linear position Transducers
  • Non-contact Linear Transducers
  • wireless Transducers
  • In cylinder Linear Transducers


Type of Transformer

  • Power transformer
  • Audio frequency transformer(AFT)
  • Radio frequency transformer(RFT)
  • Inter mediate frequency transformer(IFT)
  • Auto transformer
  • Isolation transformer
  • Driver transformer


  • Relay is a electromagnetically operated switch,
  • Relay is an automatic switch,
  • it working an electromagnetic field,
  • all electronic circuit is ex specially design and fabricated two switch on or switch off the one or more device,
  • all electronic circuit has an end width relay

Relay Applications

  • Automotive Electronics
    • Mini Plug-in Power Relays
    • Micro Plug-in Relays
    • Enclosed / Sealed Automotive Relays
    • Miniature PCB Automotive Relays and
    • Twin Automotive Relays
  • Industrial Instrumentation & Controls
  • High-end Consumer Electronics
    • Air Conditioner
    • Heater
  • Communications
    • Telecommunication system
  • Strategic Electronics

Car LED flasher Relay

  • 3-Pin Car LED Flasher Relay Fix Turn Signal – Black (DC 12V)
  • 6pin Flasher Relay for All 4 Wheeler Use 12V Dhuale Head Lamp Relay

Relay Manufactures


  • Applications
    • AC to Dc converter
    • AC Converter
    • Electronics Circuit Breaker


  • Application
    • DC Choppers,
    • Low power UPS
    • SMPS
    • Brush less DC Motor Drivers



Switch Type:

  • Pressure Switches
  • Temperature Switches
  • Flow Switches & Meters
  • Liquid Level Switches



Sensor Type

  • switching sensor
  • variable sensor
  • image processing sensor
  • RF sensor

Varies Types of Sensor

  • Accelerometer Sensor
  • Alcohol Sensor
  • Current Sensor
  • Dew Sensor
  • Distance Sensor
  • Eye Capture Sensor
  • Eye Image Print Sensor
  • Fingure Print Sensor
  • Flow Control (Water Pressure)
  • GPS Sensor Module
  • Gsm Sensor Module
  • Hear Beat Monitor
  • Humidity Sensor
  • Load Cell
  • Luminance Sensor
  • Pressure Sensor
  • Proximity Sensor
  • Solenoid Load
  • Temperature Sensor
  • Ultra Sonic Sensor
  • Vibration Sensor
  • Water Solenoid

LDO -LDO -5v, 3v3 BreakOut Board


AM & FM Modulation

Electronics Engineer Must have following Equipment

  • Scale
  • Multi meter
  • Soldering iron
  • Oscilloscope
  • Vernier caliber

What is this symbol mean of Pb?

  • Lead Free & RoHS Compliant Label solutions

What is RoHs?

  • RoHS (Restriction of Hazardous Substances) is a European Union directive that restricts the use of lead, mercury, cadmium, chromium (VI), PBBs, and PBDEs in electrical and electronic equipment as of July 1, 2006.


Timer Application

  • Timer :- status monitor of WiFi or internet using (mqtt, http, tcp/ip, net module)
  • Battery level monitor using timer with LED

LED Application

  • LED Blink Methods
    • LED Blink using Capacitor
    • LED Blink using Timer.
    • LED Blink using Miceo controller
      • Using Timer alarm
      • Using timer delay
  • LED Blink Application
    • Becone lights in Car, Bus, track, Airplane 🛬, bike, cycle (🚓🚐🚎🚍🚌🚔🚕🚖🚗🚘🚜🚙🚚🚛🚲🛴🚜,)
    • Vehicles right 👉 /left 👈 indicators in front & back also in dashboard.
    • Wifi Routers :- Wifi Connectivity indicators blink, Internet Connectivity indicator

NTC Temperature Probe



Electronics items sellers

Bangalore, India.


Ever Green Industrial Store

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You can buy All kind of magnet here like Bitter Electromagnet, Dipole Magnet, Electro Permanent Magnet, Horseshoe Magnet, Spring Magnet.

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  • Address: Shop No.150, Sadar Patrappa Rd, Dodpete, Nagarathpete, Bengaluru, Karnataka 560002.
  • Owner Siddiqali : 98866 83674.
  • Location : https://goo.gl/maps/M14u5H9MQVs



  • Module143 Address
    • Module143
      Himesh Reddivari Technologies Pvt Ltd
      #14, 2nd floor,
      Sri Ram Vilas Sweets,
      OTC Road,
      Bengaluru – 560002
      TIN: 29581359633
  • Phone : 07032366913,14
  • [email protected]

Geo Location




Shelfkey-Begur, Bangalore


Tanotis-Mahalakshmipuram, Bangalore


Coimbatore, India



Karishma Electronics

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  • Address : #8,S.P.Complex, Edayar Street, Coimbatore, Tamil Nadu 641001
  • Contact Number : 094867 73009
  • Location : https://goo.gl/maps/Wy21pRx53DC2


Kaveri Electronics

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R.K Electronics

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  • Address: 789, 789, Oppanakara St, Town Hall, Coimbatore, Tamil Nadu 641001
  • Phone: 0422 239 4040
  • WebSite : http://www.torindia.com


Krishna electronics

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  • Address: # 177, 2, M.F.C Towers, Variety Hall Rd, Town Hall, Coimbatore, Tamil Nadu 641001
  • Phone: 0422 238 6131
  • Location : https://goo.gl/maps/Rzara5oXb7r


Sunrise Electronic

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Electronics Companies

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