โก Basic Electronics Engineering (100114)¶
โฌ ๏ธ Back to Semester-1 | ๐ Home
โน๏ธ Note: The detailed unit-wise syllabus PDF for this subject wasn't in the uploaded documents โ these notes cover the standard topics taught in every "Basic Electronics Engineering" course for CSE. Replace/extend this file once you get your official unit breakdown from your department.
๐ก Why this subject? This is where Physics' "semiconductor" theory turns into actual usable components โ diodes, transistors, and amplifiers that build every circuit you'll ever touch.
๐ Semiconductor Basics (recap from Physics)¶
- P-N Junction Diode: allows current in one direction only (like a one-way valve for electricity ๐ฐ).
- Forward bias: PโN, diode conducts.
- Reverse bias: blocks current (except a tiny leakage).
- Zener Diode: a special diode designed to conduct in reverse bias once a fixed voltage is reached โ used for voltage regulation.
๐ Example: A diode in a phone charger converts AC (from the wall) into one-directional pulses โ the first step of making DC.
๐ Rectifiers (AC โ DC conversion)¶
| Type | Diodes used | Output |
|---|---|---|
| Half-wave rectifier | 1 | Uses only half the AC cycle, choppy DC |
| Full-wave rectifier (center-tap) | 2 | Uses both halves, smoother |
| Bridge rectifier | 4 | Most efficient, no center-tap transformer needed |
๐ง Quick Recall: Bridge rectifier = 4 diodes in a diamond shape = the standard used in real power adapters.
๐ Transistors (BJT)¶
- A Bipolar Junction Transistor has 3 terminals: Base, Collector, Emitter.
- Acts as a switch (ON/OFF) or an amplifier (small input current controls a much bigger output current).
- Two types: NPN and PNP (based on layer arrangement).
๐ Example: In a simple LED-blinking circuit, a transistor lets a small microcontroller pin (low current) switch a much higher-current LED/motor.
๐ Amplifiers¶
- Amplifier: boosts a weak signal (like a microphone's tiny voltage) into a usable one (loud enough for a speaker).
- Gain: output/input ratio โ how much "louder" the signal becomes.
- Common configurations: Common Emitter, Common Base, Common Collector (differ in which terminal is shared between input & output).
๐ Operational Amplifiers (Op-Amps)¶
- A general-purpose amplifier chip (e.g., IC 741) with two inputs (+ and -) and one output.
- Ideal Op-Amp: infinite gain, infinite input impedance, zero output impedance.
- Common circuits: inverting amplifier, non-inverting amplifier, comparator, summing amplifier.
๐ Basic Logic Gates (bridge to Digital Electronics, Sem 3)¶
| Gate | Symbol meaning | Output is 1 when... |
|---|---|---|
| AND | AยทB | both inputs are 1 |
| OR | A+B | at least one input is 1 |
| NOT | ฤ | input is 0 |
| NAND | (AยทB)' | NOT of AND |
| NOR | (A+B)' | NOT of OR |
| XOR | AโB | inputs are different |
๐ Example: A simple security circuit: Alarm = DoorSensor AND NOT(CodeEntered) โ alarm rings only if the door opens and the correct code was never entered.
โ Quick Revision Table¶
| Topic | One-line memory hook |
|---|---|
| Diode | One-way valve for current |
| Zener diode | Used for voltage regulation |
| Bridge rectifier | 4 diodes, most efficient ACโDC |
| BJT | 3-terminal switch/amplifier (Base, Collector, Emitter) |
| Op-amp | General-purpose high-gain amplifier chip |
| Logic gates | Foundation for all digital circuits (see Sem-3 Digital Electronics) |