Introduction: DIY Technometer Using Arduino

Hi guys in this instructables we will learn how to make Technometer with Arduino so that we can read the speed of any motor with the help of our DIY Technometer.

Step 1: Things You Need

Gor this instructables you will need following things :

Arduino uno Or

Arduino pro Mini

IR sensor Module
16x2 LCD
Push button
Bread board
9 volt battery
Connecting wires

Step 2: Basics of the Technometer Project

Tachometer is a RPM counter which counts the no. of rotation per minute. There are two types of tachometer one mechanical and other one is digital. Here we are going to design an Arduino based digital tachometer using IR sensor module to detect object for count rotation of any rotating body. As IR transmits IR rays which reflect back to IR receiver and then IR Module generates an output or pulse which is detected by the arduino controller when we press start button. It counts continuously for 5 seconds.
After 5 seconds arduino calculate RPM for a minute using given formula.
RPM= Count x 12 for single object rotating body.
But here we demonstrate this project using ceiling fan. So we have done some changes that is given below:
RPM=count x 12 / objects
object = number of blade in fan.

Step 3: Circuit & Explanation

As shown in circuit, it contains a Arduino Pro Mini, IR sensor module, buzzer & LCD. Arduino controls the reads pulse that IR sensor module generate according to object detection & calculating RPM & sending RPM value to LCD. IR sensor is used for sensing the object. We can set sensitivity of this sensor module by inbuilt potentiometer situated on IR module. IR sensor module consist an IR transmitter and a photo diode which detects or receives infrared rays. IR transmitter transmits infrared rays, when these rays fall on any surface, they reflect back and sensed by photo diode (You can understand more about it in this Line Folloewr Robot). The output of photo diode is connected to a comparator, which compare photo diode output with reference voltage and result is given as output to arduino.

IR sensor module output pin is directly connected to pin 18 (A4). Vcc and GND are connected to Vcc and GND of arduino. A 16x2 LCD is connected with arduino in 4-bit mode. Control pin RS, RW and En are directly connected to arduino pin 2, GND and 3. And data pin D4-D7 is connected to pins 4, 5, 6 and 7 of arduino. A push button is also added in this project. When we need to count RPM we press this button to start this Arduino Tachometer to count RPM for five seconds. This push button is connected to pin 10 of arduino with respect to ground.

Step 4: Code

Please copy the following code & Upload it to arduino :

#include "LiquidCrystal.h"
LiquidCrystal lcd(3, 2, 4, 5, 6, 7);
#define sensor 18
#define start 10
int delay1()
//unsigned int long k;
int i,j;
unsigned int count=0;
return count;
void setup()
pinMode(sensor, INPUT);
pinMode(start, INPUT);
pinMode(13, OUTPUT);
lcd.begin(16, 2);
lcd.print("Circuit Digest");
digitalWrite(start, HIGH);
void loop()
unsigned int time=0,RPM=0;
lcd.print(" Please Press ");
lcd.print("Button to Start ");
lcd.print("Reading RPM.....");
lcd.print("Please Wait.....");

Step 5: Testing

So I tested the DIY Technometer with my fan and as you can see, we can see the RPM count of a fan on our display.

Made with Math Contest

Participated in the
Made with Math Contest