Lab set Program-4

Develop a program to control a DC motor with Arduino board.

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Objective

To interface a DC motor with Arduino Uno in Tinkercad and control its ON/OFF operation using a transistor as a driver and a diode for back EMF protection.

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Learning Outcomes

By the end of this lab, students will be able to:

1. Understand how to drive a DC motor safely using a transistor as a switch.

2. Explain the role of a diode in protecting the circuit from back EMF.

3. Write and upload Arduino code to control the motor.

4. Build and test a motor control circuit in Tinkercad.

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Components (from Tinkercad Palette)

• Arduino Uno R3

• DC Motor

• Breadboard (small)

• NPN Transistor (2N2222)

• Diode (1N4007)

• Resistor (220Ω)

• Jumper wires

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Circuit Wiring (Exact)

1. Motor Connections

   • Motor terminal 1 → Arduino 5V pin

   • Motor terminal 2 → Collector of transistor (2N2222)

2. Transistor Connections (2N2222)

   • Emitter → Arduino GND

   • Base → Arduino Digital Pin 9 via 220Ω resistor

3. Diode Placement (for protection)

   • Place diode across motor terminals

   • Cathode (line side) → connected to Motor terminal at 5V

   • Anode → connected to Motor terminal at Collector (transistor side)

4. Power and Ground

• Arduino 5V → Breadboard positive rail

• Arduino GND → Breadboard negative rail

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Arduino Sketch

// Lab Program 4: DC Motor Control in Tinkercad

int motorPin = 9;  // Motor control via transistor base

void setup() {
  pinMode(motorPin, OUTPUT);
}

void loop() {
  digitalWrite(motorPin, HIGH);  // Motor ON
  delay(3000);                   // 3 seconds ON

  digitalWrite(motorPin, LOW);   // Motor OFF
  delay(3000);                   // 3 seconds OFF
}

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How it Works

• Arduino sends a HIGH signal on Pin 9 → current flows into transistor base → transistor switches ON → motor runs.

• Arduino sends LOW → transistor OFF → motor stops.

• The diode blocks reverse current caused by motor coil’s back EMF → protects Arduino and transistor.

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Common Mistakes & Quick Fixes

1. Motor not rotating → Check if transistor legs (E, B, C) are wired correctly.

2. Arduino resets when motor runs → Missing diode across motor terminals.

3. Motor always ON → Base resistor not connected, causing leakage current.

4. No response in Tinkercad → Check that code is uploaded and simulation is running.

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Viva / Check-Your-Understanding

1. Why can’t we connect the motor directly to Arduino pin?

2. What is the role of the transistor in this circuit?

3. Why is a diode placed across the motor terminals?

4. Can we use PWM to control motor speed? If yes, how?

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Extensions (Mini-Tasks)

1. Modify the code to make the motor run for 1 second ON, 2 seconds OFF.

2. Use analogWrite() instead of digitalWrite() to control motor speed.

3. Replace motor ON/OFF with a button press input from Arduino.

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Lab Record (Suggested Headings)

• Title

• Objective

• Components Used

• Circuit Diagram (Tinkercad screenshot)

• Arduino Code

• Output 

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Thinkercad Link:

https://www.tinkercad.com/things/bKjuTssXFdV-labset-prog-4