BASICS OF ELECTRONICS

We will be discussing….. Resistor Capacitor Diode Transister

RESISTORS Resistors are used to limit current or divide voltage and in some cases, generate heat. Used for driving circuit which requires low current and voltage than available. A two terminal non-polarized component.

Unit of resistance is ohm. Notation for resistance O- for ohm Contd… Unit of resistance is ohm. Notation for resistance O- for ohm K- for kilo ohm M- for mega ohm

Physical appearance

Color code table

Practical Use To reduce the current flowing in circuit, use resistance in parallel.

To reduce the voltage for any circuit, use resistance in series.

CAPACITORS A two terminal electronic component which stores energy in form of charge. capacitance is a measure of a capacitor's ability to store charge. A large capacitance means that more charge can be stored. Capacitance is measured in Farads(F) but prefixes like µF and pF for smaller values.

Types of capacitors Polarized which have specified positive and negative terminals. Non-polarized no defined polarity for terminals.

Practical use Used for making timer circuits, when used with resistance. Used in clipper, clamper circuit. Used for providing instantaneous large power as in flashlight of cameras. Used in DC filter circuits.

DIODES A two-terminal electronic component that conducts electric current in only one direction.

The direction of arrow shows the only possible direction of current.

Types of diodes LED i.e Light Emitting Diodes These diodes emit light when provided with power supply.

Photodiode These diode generates currents when exposed to light.

Practical use Used for making gates Used for making rectifiers Used as a switch LED as indicators Photodiodes as light detector

TRANSISTOR A transistor is a semiconductor device commonly used to amplify or switch electronic signals. Device with three terminals where one terminal can be use to control the flow of current through the other two terminals.

Contd…. The three terminals are Emitter, Base and Collector

Transistor are of two types: 1-> n-p-n A straight switch 2-> p-n-p A inverted switch

n-p-n as straight switch When base of n-p-n is connected with logic high voltage then it short circuit emitter and collector (SWITCH ON). When base of n-p-n is connected with logic low voltage then it open circuit both emitter and collector (SWITCH OFF).

p-n-p as inverted switch When base of p-n-p is connected with logic high voltage then it open circuit emitter and collector (SWITCH OFF). When base of p-n-p is connected with logic low voltage then it short circuit both emitter and collector (SWITCH ON).

Practically used… As a switch As an amplifier For realizing logic gates

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