Introduction: Worlds Simplest Anemometer

About: Art without engineering is dreaming. Engineering without art is calculating. Automotive engineer, school teacher and hobbyist photographer who loves creating!

Anemometers are simple instruments used by meteorologists to measure the speed of the wind. The term is derived from the Greek word anemos, which means wind, and is used to describe any wind speed instrument used in meteorology.

The cup anemometer is the simplest form of this instrument and in this instructable i m making a very simple anemometer with materials found in almost every household. The simplicity of the construction is not allowing exact measurments but can be used to determine a light, moderateor a strong wind, ideal for school projects or amateur home use.

The microcontroller i used to collect and process the data is a Arduino Nano but most controllers will work fine.

This is my first instructable so i will be please if you give me some feedback, thank you!


  1. Three small bottle cups
  2. One big bottle cup
  3. Tie wraps, band tape, glue
  4. A magnet
  5. One reed switch
  6. Stainless stell bolt, nuts and washers
  7. A base for the nut, i used 4mm craft plywood
  8. Arduino Nano or other microcontroller

Step 1: Assembly of the Rotor

First of all the big cut has to be drilled at the center in order to make a hole for the axis. It is important for the balance of the anemometer to make the hole exactly at center of the cup. Most bottle cups are manufactured to have a small bump or cavity on their center. I used a 6mm drill bit to open the hole, a soldering iron will also make the job.

The next thing is to devide the circumference of the big cup to three parts, this has to be also precisly made to keep the rotor in balance when it is rotated from the wind. The surface on the circumference of most cups is grooved to make it greepy, by counting the grooves and dividing by three you have the points where the small cups have to be placed.

Three small cups can be glued or better placed with tie wraps on the big cup. If you choose the second solution you have to open two holes at each small cup and one for every small cup at the big cup as seen on the pictures, this requires a lot of precision work but it makes the rotor more stable and robust.

The last thing of this step is to place the magnet inside of the big cup between two cups. I have cut a small piece, glued and secured it with band tape.

Step 2: Assemblying and Mounting the Base

The base is actually a 4mm plywood drilled for the bolt-shaft which will carry the rotor. After tightenig the bolt at the plywood you have to tighten two more nuts for the bottοm support point of the rotor and the to secure the reed contact on the shaft using tie wraps. After testing that if the rotor rotates freely and is closing the reed contact, i recommend sealing the reed contact with glue in order to protect the sensitive electonic components from rain water.

By placing two washers underneath of the rotor will reduce the friction and make the anemometer more sensitive to unstable wind currents. Don't forget to lubricate the washers, a few drops of mineral oil will reduce dramatically friction and rotor noise. At the top mount point i placed a washer and a self locking nut, carefully tighten the top nut until the rotor is stable but it must rotate freely.

Step 3: Electronics and Software

Now the hardware is ready but we have to connect it to the microcontroller in order to read the signal from the reed contact, to process it and finally to calculate approximately the speed of the wind. The reed contact board has three pins, two of the are connected to the power supply and the third is the signal which has to be connected to an interrupt pin of the Arduino, in this case at pin D4.

The last thing to do is to load the sketch SimpleAnemometer.ino to the Arduino board and enter at the fourth line the diameter of your anemometer in meters. Then open the Serial Plotter, blow the anemometer and as it starts rotating you should see some diagramms on your screen, if not just leave a comment and i will be glad to help you.