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Wiring Diagrams for Day 3 Projects

Visual Guides for Building Circuits

Diagram Legend

Symbols:
[LED]     - Light Emitting Diode
[R]       - Resistor
[BTN]     - Button/Switch
[PHOTO]   - Photoresistor
[TEMP]    - Temperature Sensor
[SERVO]   - Servo Motor
[BUZZ]    - Buzzer
[ARDUINO] - Arduino Uno Board

Colors: - Red: Power (5V) - Black: Ground (GND) - Green/Blue: Signal wires - Orange: PWM/Servo control

Project 1: Blinking LED

Components

  • 1x LED (any color)
  • 1x 220Ω resistor
  • Jumper wires
  • Breadboard

Wiring Diagram

Arduino Pin 13 ──[220Ω]──[LED +]──[LED -]── GND

Breadboard Layout

     Arduino          Breadboard
     ───────          ─────────
Pin 13 ────────────── a1
                      |
                     [R 220Ω]
                      |
                      b1 ────[LED +]
                      |
                      c1 ────[LED -]────── GND

Steps

  1. Insert 220Ω resistor from Arduino pin 13 to breadboard row
  2. Insert LED (long leg = +) in same row as resistor
  3. Connect LED short leg to GND
  4. Connect Arduino GND to breadboard ground rail

Project 2: Button Control

Components

  • 1x Button/Switch
  • 1x 10kΩ resistor (pull-down)
  • 1x LED
  • 1x 220Ω resistor (for LED)
  • Jumper wires
  • Breadboard

Wiring Diagram

        5V ────[BTN]──── Digital Pin 2
                      │
                   [10kΩ]
                      │
                     GND

Digital Pin 13 ──[220Ω]──[LED +]──[LED -]── GND

Breadboard Layout

     Arduino          Breadboard
     ───────          ─────────
5V ────────────────── + rail
                      |
                      a5 ────[BTN]──── a10
                      |                |
                     [R 10kΩ]         |
                      |                |
                      b5 ───────────── b10 ──── GND

Pin 2 ─────────────── c10

Pin 13 ────────────── d1
                      |
                     [R 220Ω]
                      |
                      e1 ────[LED +]
                      |
                      f1 ────[LED -]────── GND

Steps

  1. Connect button: 5V → one side, other side → Pin 2
  2. Add 10kΩ pull-down: Pin 2 → Resistor → GND
  3. Add LED circuit: Pin 13 → 220Ω → LED → GND

Project 3: Multiple LEDs Light Show

Components

  • 3x LEDs (different colors)
  • 3x 220Ω resistors
  • Jumper wires
  • Breadboard

Wiring Diagram

Pin 13 ──[220Ω]──[LED1]── GND
Pin 12 ──[220Ω]──[LED2]── GND
Pin 11 ──[220Ω]──[LED3]── GND

Breadboard Layout

     Arduino          Breadboard
     ───────          ─────────
Pin 13 ────────────── a1 ──[R]── b1 ──[LED1]── c1 ── GND
Pin 12 ────────────── a5 ──[R]── b5 ──[LED2]── c5 ── GND
Pin 11 ────────────── a9 ──[R]── b9 ──[LED3]── c9 ── GND

Steps

  1. Connect each LED to different digital pin
  2. Each LED needs its own 220Ω resistor
  3. All LED cathodes connect to common GND

Project 4: Light Sensor

Components

  • 1x Photoresistor
  • 1x 10kΩ resistor
  • 1x LED
  • 1x 220Ω resistor (for LED)
  • Jumper wires
  • Breadboard

Wiring Diagram

5V ────[PHOTO]──── Analog Pin A0
            │
         [10kΩ]
            │
           GND

Digital Pin 13 ──[220Ω]──[LED]── GND

Breadboard Layout

     Arduino          Breadboard
     ───────          ─────────
5V ────────────────── + rail
                      |
                      a1 ────[PHOTO]──── a5
                      |                  |
A0 ─────────────────── b1               b5 ────[R 10kΩ]─── c5 ──── GND

Pin 13 ────────────── d10 ──[R 220Ω]── e10 ──[LED]── f10 ──── GND

Steps

  1. Create voltage divider: 5V → Photoresistor → A0 → 10kΩ → GND
  2. Add LED output: Pin 13 → 220Ω → LED → GND
  3. More light = higher A0 value
  4. Less light = lower A0 value

Project 5: Temperature Sensor

Components

  • 1x TMP36 temperature sensor
  • 1x LED (for indicator)
  • 1x 220Ω resistor (for LED)
  • Optional: Buzzer
  • Jumper wires
  • Breadboard

Wiring Diagram

TMP36:
Left Pin (facing flat side)  ──── 5V
Center Pin                   ──── Analog Pin A0
Right Pin                    ──── GND

Digital Pin 13 ──[220Ω]──[LED]── GND

Breadboard Layout

     Arduino          Breadboard
     ───────          ─────────
5V ────────────────── + rail ──── a1 (TMP36 left)
                      |
A0 ─────────────────── b2 (TMP36 center)
                      |
GND ────────────────── - rail ──── c3 (TMP36 right)

Pin 13 ────────────── d10 ──[R 220Ω]── e10 ──[LED]── f10 ──── GND

Steps

  1. Insert TMP36: Flat side facing you
  2. Left pin → 5V
  3. Center pin → A0
  4. Right pin → GND
  5. Add LED indicator: Pin 13 → 220Ω → LED → GND
  6. Temperature formula: (A0 reading × 0.488) - 50

Project 6: Servo Motor

Components

  • 1x Servo motor (standard)
  • Jumper wires
  • Optional: External 5V power supply

Wiring Diagram

Servo:
Red Wire    ──── 5V
Black/Brown ──── GND
Orange/Yellow ──── Digital Pin 9 (PWM)

Breadboard Layout

     Arduino          Breadboard
     ───────          ─────────
5V ────────────────── + rail ──── Servo Red
                      |
GND ────────────────── - rail ──── Servo Black
                      |
Pin 9 ──────────────── Servo Orange

Steps

  1. Connect servo power: Red → 5V, Black → GND
  2. Connect control: Orange → Pin 9 (PWM pin)
  3. For multiple servos or high load, use external power

External Power (Optional): 

External 5V ──── Servo Red
External GND ──── Servo Black
                  Arduino GND ──── External GND (common ground)
Pin 9 ─────────── Servo Orange

Project 7: Smart Plant Monitor

Components

  • 1x Moisture sensor (or DIY)
  • 1x Photoresistor
  • 1x TMP36 temperature sensor
  • 3x LEDs (Green, Yellow, Red)
  • 3x 220Ω resistors
  • 1x Buzzer
  • Jumper wires
  • Breadboard

Wiring Diagram

Moisture Sensor ──── Analog Pin A0
Photoresistor ────── Analog Pin A1
TMP36 ────────────── Analog Pin A2

Digital Pin 13 ──[220Ω]──[LED Green]── GND
Digital Pin 12 ──[220Ω]──[LED Yellow]── GND
Digital Pin 11 ──[220Ω]──[LED Red]── GND
Digital Pin 10 ────────────[BUZZER]── GND

Breadboard Layout

     Arduino          Breadboard
     ───────          ─────────
A0 ─────────────────── Moisture Sensor
A1 ─────────────────── Photoresistor (with voltage divider)
A2 ─────────────────── TMP36 Center Pin

Pin 13 ────────────── [R]──[LED Green]── GND
Pin 12 ────────────── [R]──[LED Yellow]── GND
Pin 11 ────────────── [R]──[LED Red]── GND
Pin 10 ────────────── [BUZZER]── GND

Steps

  1. Connect all sensors to analog pins
  2. Connect each LED to different digital pin with resistor
  3. Connect buzzer to digital pin
  4. Code logic:
  5. Green: Good conditions
  6. Yellow: Warning
  7. Red: Alert + buzzer

Project 8: Security System

Components

  • 1x PIR motion sensor (or button for simulation)
  • 1x Photoresistor
  • 1x Buzzer
  • 2x LEDs (Red, Green)
  • 2x 220Ω resistors
  • 1x Servo motor
  • Jumper wires
  • Breadboard

Wiring Diagram

PIR Motion Sensor:
VCC ──── 5V
OUT ──── Digital Pin 2
GND ──── GND

Photoresistor ──── Analog Pin A0 (with voltage divider)

Digital Pin 13 ──[220Ω]──[LED Green]── GND
Digital Pin 12 ──[220Ω]──[LED Red]── GND
Digital Pin 11 ────────────[BUZZER]── GND
Digital Pin 9 ───────────── Servo Orange
Servo Red ──── 5V
Servo Black ──── GND

Breadboard Layout

     Arduino          Breadboard
     ───────          ─────────
5V ────────────────── + rail
GND ────────────────── - rail

PIR: VCC→5V, OUT→Pin 2, GND→GND
A0 ─────────────────── Photoresistor circuit

Pin 13 ────────────── [R]──[LED Green]── GND
Pin 12 ────────────── [R]──[LED Red]── GND
Pin 11 ────────────── [BUZZER]── GND
Pin 9 ─────────────── Servo Orange
Servo Red ──── 5V
Servo Black ──── GND

Steps

  1. Connect PIR sensor (3 pins)
  2. Connect photoresistor for light detection
  3. Connect LEDs for status indication
  4. Connect buzzer for alarm
  5. Connect servo for camera simulation

General Wiring Tips

Power Distribution

  • Use breadboard power rails for multiple components
  • Connect Arduino 5V to breadboard + rail
  • Connect Arduino GND to breadboard - rail
  • All components share common ground

Resistor Placement

  • Always in series with component
  • For LEDs: Resistor before LED (either side works, but standard is before)
  • For pull-up/pull-down: Between signal and power/ground

Wire Management

  • Use different colors for organization
  • Red = Power, Black = Ground, Other colors = Signals
  • Keep wires neat to avoid confusion
  • Use appropriate wire length

Testing

  • Test each component individually first
  • Verify power and ground connections
  • Check pin numbers match code
  • Use multimeter if available

Safety

  • Double-check connections before powering on
  • Verify no short circuits
  • Use appropriate resistor values
  • Disconnect power when making changes

Troubleshooting Wiring

Problem: Nothing Works

  • Check power connections (5V and GND)
  • Verify Arduino is powered (LED on board)
  • Check all connections are secure

Problem: Component Doesn't Work

  • Verify correct pin number
  • Check component orientation (LED, sensors)
  • Test component individually
  • Verify resistor values

Problem: Wrong Values

  • Check wiring matches diagram
  • Verify analog vs digital pins
  • Check voltage divider calculations
  • Test with multimeter

Problem: Components Overheat

  • Check for short circuits
  • Verify resistor values
  • Reduce current draw
  • Check power supply capacity

Quick Reference

Common Pin Assignments

  • Pin 13: Built-in LED, general use
  • Pin 9: Servo control (PWM)
  • A0-A5: Analog sensors
  • Digital 2-12: General I/O

Resistor Values

  • 220Ω: LEDs (most colors)
  • 330Ω: Blue/white LEDs
  • 10kΩ: Pull-up/pull-down, voltage dividers

Component Polarity

  • LEDs: Long leg = + (anode)
  • Electrolytic Capacitors: Marked leg = -
  • Diodes: Band = cathode (-)
  • Most Sensors: Check datasheet

Remember: When in doubt, refer to component datasheets and double-check connections before powering on!