Anemometer

DIY wind speed meter

There was a task to collect anemometer for one project, so that it was possible to take data on a computer via USB. The article will focus more on the anemometer itself than on the data processing system from it:

1. Components

So, for the manufacture of the product needed the following components:

Mitsumi Ball Mouse - 1 pc.

Ping-pong ball - 2 pcs.

A piece of plexiglass suitable size

2.5 mm2 - 3 cm copper wire

Ballpoint pen refill - 1 pc.

Chupa Chups candy stick - 1 pc.

Cable clip - 1 pc.

Hollow brass barrel 1 pc.

2. Production of the impeller

3 pieces of copper wire 1 cm long each were soldered to a brass barrel at an angle of 120 degrees. I soldered a rack from a Chinese player with a thread on the end into the barrel opening.

I cut the tube from the candy into 3 parts about 2 cm long.

I cut 2 balls in half and with the help of small screws from the same player and polystyrene glue (glue gun) attached the halves of the ball to the tubes from the lollipop.

He put the tubes with the halves of the ball on the soldered pieces of wire, and fixed everything on top with glue.

3. The manufacture of the main part

The bearing element of the anemometer is a metal rod from a ballpoint pen. In the lower part of the rod (where the cork was inserted) I inserted a disk from the mouse (encoder). In the design of the mouse itself, the lower part of the encoder rested on the mouse body forming a point bearing, there was lubrication, so the encoder was easy to spin. But it was necessary to fix the upper part of the rod, for this I picked up a suitable piece of plastic with a hole exactly in diameter of the rod (such a piece was cut from the extension system of the CD-ROMa carriage). It remained to solve the problem so that the rod with the encoder did not fall out of the point bearing, so I soldered a few drops of solder on the rod immediately in front of the holding element. Thus, the rod rotated freely in the retaining structure, but did not fall out of the bearing.

The reason why the circuit with the encoder was chosen is the following: all articles on home-made anemometers on the Internet described their manufacture on the basis of a DC motor from a player, CD-ROM or some other product. The problem with such devices is, firstly, in their calibration and low accuracy at low wind speeds, and secondly, in the non-linear characteristic of the wind speed with respect to the output voltage, i.e. To transfer information to a computer, there are certain problems; you need to calculate the law of change in voltage or current from wind speed. When using an encoder, there is no such problem, since the dependence is linear. The accuracy is highest, since the encoder gives about 50 pulses per revolution of the axis of the anemometer, but the converter circuit is somewhat complicated, in which there is a microcontroller that counts the number of pulses per second on one of the ports and sends this value to the USB port.

4. Testing and calibration

A laboratory anemometer was used for calibration.

Source: hobby-live.ru