Things and Connections

Chapter 2
Chapter 2 — O-Level M4-R5

Things and Connections

Control Systems ka working, Open loop & Closed loop aur Real Time Systems ke baare mein seekho.

🔹 Working of Control System

⚙️ Control System ek aisa system hota hai jo mechanical ya electronic devices ko control loops ke madhyam se control karta hai.

Is system ka main kaam kisi bhi machine ya device ke behavior aur working ko manage karna hota hai.

IoT me bhi computerized control systems ka bahut use hota hai. Aaj industries me control system ka use machines ke kaam ko control karne ke liye kiya jata hai. Different types ke control systems alag-alag purpose ke liye kaam karte hain.

🎯 Control System ka Purpose

Control system ka use output ko control karne ke liye kiya jata hai. Ye system following parameters ko control karta hai:

🏎️ Velocity🚀 Acceleration🌡️ Temperature⏱️ Pressure⚡ Voltage🔌 Current

✨ Features of Control System

Accuracy
Sensitivity
Energy Saving
Stability
Noise
Bandwidth
Speed

🔹 Types of Control System

Control system mainly do prakar (two types) ke hote hain:

1. Open Loop System

Jisme output ko check nahi kiya jata. Isme koi feedback signal nahi hota.

2. Closed Loop System

Jisme output ko continuously monitor kiya jata hai aur feedback signal use hota hai.

🔴 (1) Open Loop Control System

🎯 Open Loop Control System ko non-feedback control system bhi kaha jata hai kyunki is system me koi feedback signal ya error signal nahi hota.

Ye ek simple control system hota hai jisme output ko check nahi kiya jata. System sirf input ke according kaam karta rehta hai.

📊 Open Loop System Diagram

Input
Controller
Process
Output

⚡ Working of Open Loop System

Jab system start hota hai to controller process ko control karta hai aur output produce hota hai. Lekin output sahi hai ya galat, iska feedback system ko nahi milta.

Isliye agar error ho bhi jaye to system usse automatically correct nahi karta.

💡 Examples of Open Loop

🚿
Water Heater

Jab ON kiya jata hai to continuously pani garam karta hai jab tak OFF na kare.

🌀
Ceiling Fan

Speed set karne ke baad environment ke hisaab se khud speed change nahi karta.

💡
Light Bulb

Switch ON karne par jalta rehta hai, din ya raat se isko khud farq nahi padta.

🔴 (2) Closed Loop Control System

🔄 Closed Loop Control System ko feedback control system bhi kaha jata hai kyunki isme feedback signal use hota hai.

Ye system continuously output ko monitor karta hai aur agar error milta hai to usse automatically correct karta hai.

📊 Closed Loop System Diagram

Feedback
Input
⨯
Error
Controller
Process
Output

⚡ Working of Closed Loop System

Is system me output ka kuch part feedback ke roop me wapas controller ko diya jata hai. Controller actual output aur desired output ko compare karta hai.

Agar dono me difference hota hai to controller error ko reduce karta hai aur output ko improve karta hai. Isliye closed loop system jyada accurate aur efficient hota hai.

🔹 Real Time System

⏱️ Real Time System ek aisa system hota hai jiska use un kaamon ke liye kiya jata hai jo time se related hote hain aur jinhe ek fixed time period ke andar complete karna zaruri hota hai.

Agar system given time ke andar result provide nahi karta to system fail maana jata hai.

Real time system me fast processing aur quick response bahut important hota hai.

🌟 Examples of Real Time System

✈️

Air Traffic Control System

Ek second ki delay se bhi bada accident ho sakta hai, isliye iska response turant aana zaruri hai.

🚘

Automation Driving System

Agar aage koi object aata hai to system ko microseconds me break apply karna hota hai.

💡 Ye systems real-time data ko process karte hain aur turant decision lete hain!

🔹 What is Thermostat

🌡️ Thermostat ek aisa component ya device hota hai jo kisi physical system ke temperature ko control karta hai aur feedback provide karta hai taaki system ka temperature desired point ke aas-paas bana rahe.

Thermostat ka main kaam temperature ko monitor karna aur uske according heating ya cooling ko control karna hota hai. Jab temperature fixed limit se jyada ya kam ho jata hai to thermostat automatically system ko ON ya OFF kar deta hai.

📝 Ye ek closed loop control device hota hai kyunki isme continuously feedback use hota hai.
Smart Thermostat

⚙️ Working of Thermostat

  • Environment ka temperature sense karta hai
  • Desired temperature se compare karta hai
  • Temperature kam ho to heating start karta hai
  • Temperature jyada ho to heating band kar deta hai

👉 Is process ki wajah se system ka temperature stable bana rehta hai.

💡 Uses of Thermostat

Thermostat ka use different devices aur systems me kiya jata hai:

🏢 Building heating system❄️ Air Conditioner (AC)💧 Water heater♨️ Oven
👉 Example: AC me thermostat room temperature ko maintain karta hai.

🔹 OSI Model (Open System Interconnection)

🌐 OSI Model ek reference model hai jo ISO (International Organization for Standardization) ne 1984 me develop kiya tha.

Ye model network communication ko samajhne ke liye use hota hai. OSI model communication process ko different layers me divide karta hai taaki data transmission easy aur organized ho sake. Is model me total 7 layers hoti hain aur har layer ka apna specific kaam hota hai.

📊 Layers of OSI Model

7
Application Layer

Network process to application

6
Presentation Layer

Data representation & encryption

5
Session Layer

Interhost communication

4
Transport Layer

End-to-end connections & reliability

3
Network Layer

Path determination & logical addressing

2
Data Link Layer

Physical addressing & MAC

1
Physical Layer

Media, signal & binary transmission

1 Physical Layer

Ye OSI model ki sabse lowest layer hoti hai. Is layer ka kaam data ko electrical signals, radio signals ya optical signals me convert karke transmit karna hota hai.

👉 Devices: Hub, Cable, Connector

2 Data Link Layer

Ye layer error-free data transfer provide karti hai. Iska kaam: Data framing, Error detection, MAC addressing.

👉 Device: Switch

3 Network Layer

Ye layer source se destination tak data ka route decide karti hai. Is layer me IP addressing aur routing ka kaam hota hai.

👉 Protocols: IPv4, IPv6

👉 Device: Router

4 Transport Layer

Ye layer end-to-end communication provide karti hai. Iska kaam: Data delivery, Error control, Flow control.

👉 Protocols: TCP, UDP

5 Session Layer

Ye layer communication sessions ko establish, manage aur terminate karti hai. Yani devices ke beech connection ko maintain karti hai.

6 Presentation Layer

Ye layer data ko readable format me convert karti hai. Iska kaam: Encryption, Decryption, Data formatting.

7 Application Layer

Ye topmost layer hoti hai jahan user directly interact karta hai. Ye layer network services provide karti hai.

👉 Examples: HTTP, FTP, SMTP

🔹 TCP/IP Model

🌐 TCP/IP model internet communication ka practical model hai.

Ye WWW (World Wide Web) ka main protocol model hai jiska use internet par packets send karne ke liye kiya jata hai. TCP/IP model end-to-end communication provide karta hai. Is model ko 1970 aur 1980 ke beech Department of Defense ne develop kiya tha.

📊 TCP/IP Layers

4
Application Layer

Covers Application, Presentation, Session layers of OSI

3
Transport Layer

Covers Transport layer of OSI

2
Internet Layer

Covers Network layer of OSI

1
Network Access Layer

Covers Data Link and Physical layers of OSI

1. Application Layer

Ye layer application, presentation aur session layer ka combined form hoti hai. User ko network services provide karti hai.

👉 Protocols: HTTP, FTP, SMTP

2. Transport Layer

Ye layer reliable communication provide karti hai.

👉 Protocols: TCP, UDP

3. Internet Layer

Ye layer routing aur addressing ka kaam karti hai.

👉 Protocol: IP (Internet Protocol)

4. Network Access Layer

Ye layer physical transmission aur hardware communication ka kaam karti hai. Isme data link aur physical layer dono include hoti hain.

🔹 Transmission Mode

📡 Transmission mode batata hai ki data ek device se doosri device tak kis direction me transfer ho raha hai.

Communication ke flow ko transmission mode kehte hain. Transmission mode mainly 3 prakar ke hote hain: Simplex, Half-Duplex, Full-Duplex.

🔴 1. Simplex Mode

Simplex mode me communication sirf ek direction me hota hai. Yani sender data bhej sakta hai lekin receiver data wapas send nahi kar sakta.

A
Sender
B
Receiver
📻 Radio📺 TV🎛️ Remote

🔴 2. Half-Duplex Mode

Half-duplex mode me dono directions me communication possible hota hai, lekin ek samay par sirf ek direction me communication hota hai. (Semi-duplex)

A
One direction at a time
B
📻 Walkie-Talkie

🔴 3. Full-Duplex Mode

Full-duplex mode me dono devices ek hi samay par data send aur receive kar sakte hain. Ye sabse fast communication mode hota hai.

A
Simultaneously
B
📱 Mobile Phone💻 Internet

🔹 Transmission Media

🌐 Transmission media ek communication path hota hai jiske through data ek device se doosri device tak transfer kiya jata hai.

Simple words me: “Transmission media = data travel karne ka medium”

Jab bhi do devices aapas me communicate karte hain to data kisi na kisi medium ke through transmit hota hai. Ye medium wired bhi ho sakta hai aur wireless bhi.

1. Guided Media

Wired media jisme data physical cables ke through transfer hota hai.

2. Unguided Media

Wireless media jisme data hawa (air) me electromagnetic waves ke form me transfer hota hai.

🔴 1. Guided Media (Wired Transmission Media)

Guided media me devices ke beech physical connection hota hai. Yani data cables ya wires ke through transmit hota hai. Isme signals ek fixed path follow karte hain.

🔒 High security✅ Stable communication⚡ Fast data transfer🔇 Noise kam hota hai

1 Twisted Pair Cable

Ye data transmission ka sabse common aur sasta medium hota hai. Isme do copper wires hoti hain jinko plastic cover se insulated kiya jata hai aur dono wires ko aapas me twist kiya jata hai.

💡 Twisting ka main purpose noise aur interference ko kam karna hota hai.
Features
  • ✔️ Low cost
  • ✔️ Easy installation
  • ✔️ Flexible cable
Uses
  • 📞 Telephone lines
  • 💻 LAN network
Twisted Pair Cable

2 Coaxial Cable

Iska use heavy signals aur video signals ko transmit karne ke liye kiya jata hai. Jahan twisted pair proper signal transfer nahi kar pati, wahan coaxial cable use hoti hai.

Structure:1. Center copper wire2. Plastic insulation3. Metallic shield4. Outer plastic cover
Features
  • ✔️ Better signal quality
  • ✔️ Long distance
  • ✔️ Noise resistance
Uses
  • 📺 Cable TV network
  • 🌐 Internet connection
Coaxial Cable

3 Fiber Optics Cable

Ye sabse fast transmission medium mana jata hai. Is cable me digital data ko light signals ke form me transmit kiya jata hai (Electrical signal ki jagah light ka use).

Light Source Fiber Tube Detector
Features
  • 🚀 Very high speed
  • 🌍 Long distance
  • 🔒 Secure & No EMI
Uses
  • 🌐 Internet backbone
  • 📡 Telecom networks
Fiber Optics Cable

🔴 2. Unguided Media (Wireless Transmission Media)

Unguided media me devices ke beech koi physical connection nahi hota. Isme data air ke through electromagnetic waves ke form me transfer hota hai.

📶 No physical cable📱 Mobility support🌍 Large area coverage⚡ Easy communication

1 Radio Waves

Radio waves ko generate karna aur use karna bahut easy hota hai. Ye long distance communication ke liye use hoti hain aur objects ke through bhi travel kar sakti hain.

Range: 3 KHz – 300 GHz

Features
  • ✔️ Long distance
  • ✔️ Omnidirectional
  • ✔️ Large coverage
Uses
  • 📻 Radio communication
  • 📺 TV broadcasting
Radio Waves

2 Microwave

Microwave waves mainly long distance communication ke liye use hoti hain. Ye direct line-of-sight communication follow karti hain, isliye towers ko face-to-face hona zaruri hai.

📝 Inki wavelength 1 meter se 1 millimeter ke beech hoti hai.
Uses
📡 Satellite📱 Mobile Comm.🛰️ Radar Systems
Microwave Communication

3 Infrared Waves

Infrared waves ka use short-range communication ke liye kiya jata hai. Ye waves solid objects (jaise walls) ke through pass nahi ho sakti.

Uses
🎛️ TV Remote📶 Short-range Wireless
Infrared Waves
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