Build a Simple Tachometer at Home

Hey there, in this instructable I will show you how you can make a simple tachometer at your home, to keep this simple i have given great details with simple explanation that anyone could follow.

What is a tachometer? well to answer this let me explain a situation to you

Imagine you are doing one of your favorite project using a DC motor but you don't know when you power it up at what speed the motor rotates, the rotation usually measured as revolutions per minute is the measurement used in this case.

So when the motor is running the shaft rotates at very fast speed and it is not possible to calculate the rpm by just looking at that so we need some device and this device is called a tachometer.

There is a small catch here you will have to add a small sticker/tape on the rotating part before you point this tachometer and the reason is the sensor needs some reference point that is considered as an obstacle.

What happens in the backend is whenever the ir sensor hits on that sticker it is considered as an obstacle and Every second, calculates RPM from the counter and displays it on the OLED and this conversion is carried out with the help of code that will be fed to the nano.

I wont be revealing all the details here since this might ruin the fun of reading that you will get from the below steps so to begin with i have also given a video in the end that you can watch if you have any questions.

Supplies

Here is the list of components that you need to build this project

Arduino Nano

OLED display

IR sensor module

Soldering lead and iron

Wire trimmer

Super glue

Hot glue(optional)

DC motor and battery for testing

Few cables that are flexible

3D printer and pla filamament

Slicer

Step 1: Shrink the Size

The first step is to shrink the size! What does this mean might be your question, Well instead of these cable pieces if you just used the jumper wires then the size of the components will be big and the overall size will become bigger and bigger.

I used the wires that I recycled from the nonworking servo motor, These cables serve well for this project and its very flexible.

Start by soldering the wire to the pins directly and make sure there are no any content points that may cause some issues while the project is working.

If necessary you can add a small layer of hot glue to insulate the soldered points.

End of this step you will have OLED and ir sensor that looks like the last image in this step.

Step 2: 3d Design and Printing

I designed the case for this project using Tinkercad it is easy if you are a beginner too you can make some simple designs for your project and make it much more interesting.

I made the base and the lid first and imported the files to Cura slicer, for the slicing I followed the settings given in this step.

There is no need of any rafts or supports at the time of printing, use pla filament and the color is totally left to you

printing time for both the parts combined is less than 2 hours and you can expect very good quality print, end of this step you should have the frame ready.

Step 3: Circuit

The connections are really simple, i wanted to make this project fit in a small box so i soldered the wires to the arduino nano directly, This shrinks the size of the project to a great extent.

We have only 2 components here and i have given the connections below

IR Sensor

Connected to 5V, GND, and digital pin D6 of the nano board

OLED Display

Connected to 3.3V, GND, SCL to A5, and SDA to A4 pins on the nano

This completes your circuit for this project, now you can head over to Arduino ide, connect the nano board to computer and paste this below code

After you click on the upload button the display screen pops up showing the rpm text, now you can simply check the project by just hovering your hand in front of the sensor, The rpm values should change.

This entire setup now will be installed in a 3d printed case and we will see how this can be done.

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Step 4: Finishing

There is no much work in this step, all you have to do is fix all the assembled electronics inside the 3d printed case.

I have given a slot through which you can provide power to the board using USB cable, follow the placement as i did and place the cover ontop of this and use superglue to couple this together.

make sure there are no wires that come in front of the IR sensor, this is because if there is any obstacle the sensor might give improper results.

Now to use this project all you have to do is power this up with a USB cable and wait for the display to on.

With the help of a battery connect the DC motor and to its shaft attach a small piece of tape and point this device you should instantly see the readings of the rotation.

so why tape? This is because it helps the sensor detect the reflective parts of a rotating object

Like this you can measure the RPM of simple electronics that you will be using in your projects, Thank you for showing interest

Step 5: Video Tutorial

You should not miss the working of this tachometer, i have used battery to power the DVD motor you can replace this motor with any BO or gear motor.

I would not say that this tachometer is highly precise but it does the job, This was all about building this project, if you have any suggestions ask me in the comments and i will reply soon.

Try building this project and you will really be amazed, Thank you and have a great build.