Measuring wind speed with a DIY anemometer

Needed parts for a DIY anemometer

Needed parts for a DIY anemometer

Many of us have wondered whether it is possible to install a wind turbine at their place and whether there will be enough wind to make it work efficiently. Well, it is not that hard to find that out. This article will guide you through the process of creating a DIY anemometer, which can be assembled from parts that you have laying around.This is the list of the parts that you’ll need:

  • Three easter eggs – we used Kinder Surprise, but just about any of them will do
  • Three straws – we used the 5mm thick ones
  • Telephone wire – the length of the cable will depend on how high do you plan to mount it
  • A small DC motor (from a broken Walkman, a toy or even a vibrating battery powered shaver)
  • Instant glue, duck tape, some toothpicks, a stapler and a multimeter
Cut the caps and the straws

Cut the caps and the straws

Obviously the first step will be to unwrap the easter eggs and eat the chocolate – you will need the energy ;) After you are done playing with the toys, the first step will be to cut the lids of the plastic containers. You will also need to cut to length the straws. The lids will be used as the blades and the straws will be used as arms. The ideal length of the straws will depend on the actual size of the blades and the thickness of the arms, but in our anemometer we cut the straws in two thirds of their original length.

Attachs caps to straws

Attachs caps to straws

Once we have both the arms and the blades of our future anemometer, we need to attach them one to another with the stapler. Try to attach the straw pointing straight and parallel to the open surface of the cover. This will be important to the overall balance of the rotating part of the anemometer, so try to make the assembly equally for all three arms.

Attach the straws to the central cover

Attach the straws to the central cover

Once we have the arms assembled, we will need to attach them to the central cover which will also protect our motor from rain. It will be easier to make a hole in the central cover before you attach the arms. This hole will be used to attach the shaft of the motor later. As we have three arms, each of them will be on 120 degrees from the others. You can do that by using a triangle which corners are 90, 60 and 30 degrees. On the picture in the right, you can see how to align the arms with the help of the triangle.

Remote the insulation from the wires

Remote the insulation from the wires

Next, you will need to remove the insulation from the end of the telephone cable and to expose the copper wires inside. Try to make it in a way matching the one shown on the picture in the right.

Connect the wires to the motor

Connect the wires to the motor

Once the coper wires are exposed, attach them to the contacts of the motor. The direction doesn’t really matter for our anemometer. After the motor is attached to the wire, make sure that you isolate it well with the duck tape.

Attach the motor to the stick

Attach the motor to the stick

Next we will need to mount the motor on top of a stick. Try to attach it as firmly as possible, either by using duck tape or anything else that you prefer. You only need to make sure that you chose a stick that will be able to be inserted into the central cover of the blades.

Attach the cover to the motor

Attach the cover to the motor

Now the only thing that you need to do is to attach the cover to the motor and you have your first DIY anemometer! Try to blow into the blades to make sure it spins and then connect the multimeter to the other end of the wire. You will need to set it to measure voltage on DC, preferably on the low end of it’s scale – 200mV in our occasion. You should get some current flowing once you blow into the blades or you rotate them by hand. We managed to get around 100mV by rotating the blades by hand.In order to match the voltage to the wind speed, you can just drive your car with a fixed speed, then ask your friend to stick the anemometer out of the window and note down the average voltage that is produced. You will most probably need to get readings from 10 to 50 km per hour with a 5km per hour step. We got the following readings from our anemometer and as it turned out, there is a linear dependency:

  • 10 km/h ~ 3 m/s – 17 mV
  • 15 km/h ~ 4 m/s – 26 mV
  • 20 km/h ~ 5.5 m/s – 37 mV
  • 25 km/h ~ 7 m/s – 47 mV
  • 30 km/h ~ 8.5 m/s – 57 mV
  • 35 km/h ~ 10 m/s – 66 mV
  • 40 km/h ~ 11 m/s – 77 mV
  • 45 km/h ~ 12.5 m/s – 87 mV
  • 50 km/h ~ 14 m/s – 96 mV
Anemometer up and spinning

Anemometer up and spinning

Once you get the scale sorted out, just attach the anemometer on the end of a long bamboo or anything that you might have available in order to elevate the anemometer at least to 5m above the surface. Try to put it on an open space, far from trees or buildings so you can get accurate readings. And that’s about it, we will be waiting for your comments and wind speed readings!

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