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Writer's pictureSanskruti Ashtikar

Building a Digital Tachometer Using TinkerCAD

Updated: Nov 23

A tachometer is a device that measures the rotational speed of an object, typically in revolutions per minute (RPM). Digital tachometers are used in various applications, from automotive engines to industrial machines, to monitor and control speed. In this article, we'll walk you through how to design and simulate a digital tachometer using TinkerCAD, a powerful yet user-friendly online platform for 3D design, electronics simulation, and coding.





Materials Needed:


  • Arduino Uno

  • IR Sensor Module

  • 16x2 LCD Display

  • Breadboard

  • Jumper Wires

  • 220-ohm Resistor

  • Potentiometer (10k ohm)

  • DC Motor (optional for practical testing)


Step 1: Understanding the Circuit Design


The core of our digital tachometer is the Arduino Uno microcontroller, which reads signals from an IR sensor to calculate the RPM of a rotating object. The IR sensor module consists of an infrared LED and a photodiode. When the object interrupts the IR beam, the sensor detects the change and sends a pulse to the Arduino. By counting these pulses over time, the Arduino can determine the speed of the object.

We'll also use a 16x2 LCD display to show the RPM value in real time.


Step 2: Setting Up the Components in TinkerCAD


  1. Arduino Uno: Place the Arduino Uno on the TinkerCAD workspace. This microcontroller will serve as the brain of the tachometer.

  2. IR Sensor Module: The IR sensor has three pins: VCC, GND, and OUT. Connect the VCC pin to the 5V pin on the Arduino, GND to GND, and the OUT pin to digital pin 2 on the Arduino. This connection will allow the Arduino to read the pulses from the sensor.

  3. 16x2 LCD Display: This display will show the RPM value. It has 16 pins, but we'll only connect the essential ones:

    • Connect VSS to GND and VDD to 5V.

    • Connect the VO pin to the middle terminal of a 10k ohm potentiometer, with the other two terminals connected to 5V and GND. This controls the contrast.

    • Connect RS (Register Select) to digital pin 7 on the Arduino.

    • Connect RW (Read/Write) to GND (for writing mode).

    • Connect E (Enable) to digital pin 8 on the Arduino.

    • Connect D4, D5, D6, and D7 (data pins) to digital pins 9, 10, 11, and 12 on the Arduino, respectively.

    • Connect the A (Anode) pin through a 220-ohm resistor to 5V and the K (Cathode) pin to GND for the backlight.

  4. DC Motor (Optional): If you want to test the tachometer with a real rotating object, you can add a DC motor. Connect one terminal of the motor to the positive terminal of the power supply and the other terminal to the ground. You can also use an H-bridge to control the motor speed via the Arduino.

  5. Wiring: Use jumper wires to make the connections as described above. TinkerCAD makes it easy to visualize and connect components, so take your time to ensure all connections are correct.





Step 3: Writing the Arduino Code


Now that our circuit is ready, it's time to write the code that will control the digital tachometer. Below is a sample code that reads the IR sensor input, calculates the RPM, and displays it on the LCD:


#include <LiquidCrystal.h>
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
volatile int pulseCount = 0;
unsigned long lastTime = 0;
float rpm = 0;
void setup() {
  lcd.begin(16, 2);
  lcd.print("RPM:");
  attachInterrupt(digitalPinToInterrupt(2), countPulse, RISING);
}
void loop() {
  unsigned long currentTime = millis();
  if (currentTime - lastTime >= 1000) {
    rpm = (pulseCount / 20.0) * 60.0; // Assuming a single pulse per revolution
    lcd.setCursor(4, 0);
    lcd.print(rpm);
    lcd.print("    "); // Clear any previous digits
    pulseCount = 0;
    lastTime = currentTime;
  }
}
void countPulse() {
  pulseCount++;
}

Step 4: Simulation in TinkerCAD


Once the code is uploaded, you can simulate the circuit. TinkerCAD allows you to simulate the rotating object by adjusting the IR sensor input manually or by using a virtual motor setup.

  • Start the Simulation: Press the "Start Simulation" button in TinkerCAD. The LCD display should show the RPM value. If you're using a DC motor, you can adjust its speed and see how the RPM value changes on the display.

  • Troubleshooting: If the RPM value doesn't display or fluctuates wildly, double-check your connections, and ensure the IR sensor is correctly positioned to detect the rotating object.





Step 5: Practical Application and Testing


If you have access to physical components, you can transfer the design from TinkerCAD to a real-world breadboard setup. Follow the same wiring instructions and upload the Arduino code to your physical Arduino Uno. Test the tachometer by pointing the IR sensor at a rotating object, such as a fan or motor, and observe the RPM readings.


Conclusion


Congratulations! You've successfully built and simulated a digital tachometer using TinkerCAD. This project demonstrates the versatility of Arduino and TinkerCAD as tools for learning and prototyping electronics. With some modifications, you can adapt this tachometer for various applications, such as monitoring motor speeds in robots, vehicles, or industrial machines.

Experiment with different sensors, displays, or even add features like data logging or wireless transmission to make your project even more advanced. TinkerCAD provides a great platform to experiment and bring your ideas to life. Happy tinkering!


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