• 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

or F = 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.

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 :

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.

Electronics devices Types

Electronics devices Types are generally two types Active and Passive Components

  • Active Components
    • Semiconductors
    • Diode
    • Transistors
    • Integrated Circuits
    • Opto electronics Devices
    • Display technologies
    • Vacuum tubes (Valves)
    • Discharge device
    • Power Sources
  • Passive Components
    • Resistors
      • What is Resistance?
      • Resistor – Tutorial
    • Capacitors
    • Magnetic Devices (Inductive)
    • Memristor
    • Networks
    • Transducers, Sensors, Detectors
    • Antennas
    • Assemblies, Modules
    • Prototyping Aids
  • Electromechanical
    • Piezoelectric devices, Crystals, resonators
    • Terminals and Connectors
    • Cable Assemblies
    • Switches
    • Protection Devices
    • Mechanical Accessories




  • 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.
  • + – + –

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
  • Transistor can be used as a switch, amplifier.
  • β = Ic/Ib

  • Example Ic = 0.5 to 1.5mA, Ib= 20-40uA, what is β=?
    • Answer β = 50.


  • BJT – bipolar Junction Transistor
  • Application
    • DC to AC Converter
    • Induction Motor driver
    • UPS
    • SMPS
    • 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

RC 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


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


Types of transducer

  • 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

Electronics Equipment

Electronics Engineer Must have following Equipment

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

Symbol Pb & RoHs

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.


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.
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  • 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

The Electronics Course

  • Electronics
  • PIC
  • ARM
  • C
  • C++
  • LabVIEW
  • German
  • RTOS
  • Linux


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