INSTANT REFERENCE

BASIC ELECTRONICS

RESISTORS

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SMD resistor

UNIT OF MEASUREMENT OF RESISTORS

OHMS Ω

  • 1 Ω
  • 1000 Ω = 1 Kilo Ω (1K Ω)
  • 1000 KiloΩ = 1 Mega Ω (1M Ω)

What is a resistor ?

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. (Source : Wikipedia)

What is the use of a resistor in a circuit

  • FUSE (fusible resistors)
  • Resistor to sense temperatures. (Thermal Sensing resistance NTC / PTC Value Decreases with rise in temperature and Value Increases with drop in Temperature)
  • Resistor as Current limiting resistor (CLR)
  • Use two or more resistor to make a voltage divider

VOLTAGE DIVIDER

vd
  • Vin  –   ⚡ Input Voltage
  • R1    –   Resistance 1
  • R2    –  Resistance 2
voltage divider formula

What is the use of a resistor in a LAPTOP circuit

  • PULL UP RESISTOR
  • PULL DOWN RESISTOR / PROTECTION MODE
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    Pull up resistors

    Pull-up resistors are simple fixed value resistors, that are connected between the voltage supply and the particular pin. These resistors are used in digital logic circuits to ensure a logic level at a pin


     

    Pull Down resistors

    Pull-down resistors also works in the same way. But, they pull the pin to a low value. Pull-down resistors are connected between a particular pin on a microcontroller and the ground terminal.

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    resistors formula

    Diodes

    Diode

    Training Class Important Notes 1
    A diode is an electrical device allowing current to move through it in one direction

    Zener Diode

    Zener diode symbol
    A Zener diode is a type of diode that allows current to flow not only from its anode to its cathode, but also in the reverse direction, when the Zener voltage is reached.

    Schottky's Diode

    Schottky diode symbol

    When sufficient forward voltage is applied, a current flows in the forward direction.

    diodes

    CAPACITORS

    A capacitor is a passive two-terminal electronic component that stores electrical energy in an electric field. The effect of a capacitor is known as capacitance.

    UNIT OF MEASUREMENT OF CAPACITOR ISFARADS

    FOR AC ITS LOW RESISTANCE

    FOR DC ITS HIGH RESISTANCE

    TYPES OF A CAPACITORS USED IN MOTHER BOARD

    Polarized Capacitor

    cap

    A polarized (“polar”) capacitor is a type of capacitor that have implicit polarity — it can only be connected one way in a circuit. The positive lead is shown on the schematic (and often on the capacitor) with a little “+” symbol.

    Non Polarized Capacitor

    cap 3

    A non-polarized (“non polar”) capacitor is a type of capacitor that has no implicit polarity — it can be connected either way in a circuit.

     

     

     

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    MODES OF CAPACITOR USED IN MOTHERBOARD

    1. COUPLING
    2. DECOUPLING
    3. SNUBBER

    INDUCTORS

    inductor
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    inductor 2
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    ALLOWS ONLY DC TO FLOW

    HIGH RESISTANCE FOR AC

    LOW RESISTANCE FOR DC

    TRANSISTORS

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    Digital Transistors

    digital transistor is a transistor that has an internal resistor from the input to the base and a pull up/down resistor between the base and the emitter.

    digital transistor
    digital transistor

    Know more info on “Digital Transistors

    MOSFETS

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    What is a MOSFET ?

    The current flowing in the channel of the MOSFET is controlled by the voltage present on the gate. As such MOSFETs are widely used in applications such as switches and also amplifiers.

    TYPES OF MOSFETS

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    DAP – DRAIN HAS ANODE IN P-CHANNEL

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    SAN – SOURCE HAS ANODE IN N-CHANNEL

    How to Recognize N CHANNEL and P CHANNEL MOSFET

    EVEN NUMBER OR ODD NUMBER

    DIRECTION OF AN ARROW OF GATE

    BY MULTIMETER


    SAN AND DAP METHOD


     

    In P Channel Mosfet we do not need gate permission to pass current / voltages from Drain to Source. (Voltages passes through a diode with ~0.5 voltage drop)

    In N Channel Mosfet we do not need gate permission to pass current / voltages from Source to Drain. (Voltages passes through a diode with ~0.5 voltage drop)

    We need gate permission to turn on mosfet in order to pass voltages in reverse bias condition
    Conditions to turn on / off mosfet used on laptop motherboards

    ON – HALF OF SOURCE VOLTAGE or NORMALLY 0~9V

    OFF – SAME AS SOURCE VOLTAGE

    ON – ONE AND HALF TIME DRAIN  VOLTAGE or NORMALLY 24~28 FOR 19V FOR FULL POTENTIAL

    OFF –  0V OR GND  OR IF VOLTAGE IS LESS THAN DRAIN OUTPUT IT THERE BUT NOT AT FULL POTENTIAL

    In this condition, if the MOSFET is “ON” then the MOSFET will allow current / voltage to flow from Source to Drain Or Drain to Source.

    DUAL CHANNEL MOSFETS

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    Dual Channel mosfets are the type of MOSFETS where two mosfets are placed inside a single IC.

    Two mosfets can be of both N-Channel or Both P-Channel, or both of different type.

    JFET

    JFETs can have an n-type or p-type channel.

    JFETS also works similar to MOSFETS

    But operational gate voltage required is Very low compared to mosfets, JFET’s need High Or Low in order to turn on the fet.

    More info on JFET go here.

    GATES

    COMPARATORS

    A comparator is a device that compares two voltages or currents and outputs a digital signal indicating which is larger. It has two analog input terminals and and one binary digital output .