# How to Build Your Own Anemometer Using Reed Switches, Hall Effect Sensor and Some Scraps on Nodemcu.

Contents

In this post, we will learn How to Build Your Own Anemometer Using Reed Switches, Hall Effect Sensor and Some Scraps on Nodemcu. Since I started with the studies of Arduino and the Maker Culture I have liked to build useful devices using junk and scrap pieces such as bottle caps, pieces of PVC, drink cans, etc. I love to give a second life to any piece or any material. A large part of the materials used here is scrap removed from some equipment and recycled.

### Part 1 – Hardware

When I started a project of a weather station for my own I realized that the measurement of the intensity and direction of the wind would not be very easy or cheap. After several months I present to you this project that uses mostly recycled materials and very cheap electronic parts easily found in any electronic store.

This post has 2 parts.

Part 1 – Construction of the devices Anemometer and Wind Vane Direction.

See the video to know the final solution.

How to build your own Anemometer using Hall Effect Sensor and Reed Switches

Project description

The anemometer is a device capable of measuring the wind speed and its direction. Using a Hall Effect sensor we will be able to count how many rotations the cups give in a period of time. The intensity of the wind is proportional to the speed of rotation of the axis. With some simple physics equations, you can determine the linear velocity of the wind, at that moment. We will explain all of them in part 2.

And the direction of the wind we will measure through a windshield with a neodymium magnet and reed switches. The vane points in the direction of the wind and the magnet attached to it will connect the reed switches allowing the electric current to pass through the connection (or connections). Circuits that have positive current indicate the direction of the wind, like a compass.

We have 8 circuits that will emulate 16 directions : 4 cardinal and 4 collateral points when 1 switch is activated (N, NE, E, SE, S, SW, W, NW) and when 2 switches are activated simultaneously we have 8 sub collateral points (NNE, ENE, ESE, SSE, SSW, WSW, WNW, NNW).

The wind speed and direction will be calculated and determined by a sketch in the nodemcu. But this will be explained in part 2. Now let’s go to the hardware assembly.

Disclaimer: This anemometer should not be used for professional purposes. It is only for academic or home use.

Note: English is not my natural language. If you find grammatical errors that prevent you from understanding the project, please let me know to correct them. Thank you so much.

### Step 1: Bill of Materials

• Wind Vane

8 x Reed Switches

8 x 10 k ohms resistors

10 cm PVC pipe

2 PVC caps 5 cm diameter

1 PVC cap 2.5 cm diameter

1 CD4051 Analog Multiplexer

1 plastic disk

20 x 20 strong plastic piece

1 Neodymium magnet (The dimensions of the magnet must allow two switches to be connected simultaneously. Mine is 0.5 x 0.5 cm and it is doing well.)

10 different colors wires

1 Generic PCB

1 ball bearing with the same diameter of the aluminum tubes

1 aluminum tube approx 20 cm

1 aluminum tube approx 10 cm

1 hose clamp

Epoxy Mass

Instant Glue – cyanoacrylate and sodium bicarbonate

• Anemometer

2 Ping pong balls

4 wooden or aluminum sticks approx 12 cm

1 ball bearing

1 aluminum tube approx 5 cm

3 pieces of wires different colors

1 hall sensor SS49E

1 neodymium magnet

Epoxy Mass and Instant Glue – cyanoacrylate and sodium bicarbonate

2 plastic taps approx 3 a 5 cm diameter

1 PVC cap and 5 cm PVC pipe

1 PVC cap 2.5 cm diameter

• Nodemcu
• Plastic Case for Electronic Projects
• Soldering Iron
• 1 PVC Pipe approx 2 meters and “T” PVC Connector
• 1 PVC 90 degrees connexion
• 5V power supply (I’m using solar panel)