DIY Anemometer (Wind Meter)

Using this app along with a very simple homemade device, you’ll have a working anemometer for measuring wind speed or the airflow in a ventilation system. You can choose the type of anemometer which best suits your needs.
The wind speed is determined by measuring the rotation speed of the magnet in your iPhone’s magnetometer. The relationship between the rotation speed and the speed of airflow is set in each version of the anemometer and can be adjusted.
You can make improvements to the suggested designs or make and calibrate your own.
In order to select units of measurement (m/s, km/h, ft/s, mph, knots, Bft) or the average value ("Avg1" - most recent value, "Avg3" and "Avg7" - average value) press the seven-segment display.
Don’t forget to put a protective cover on your iPhone.
Specifications ("Outdoor" anemometer):
• Measurement range from 0.5 m/s (1 mph) to 15 m/s (34 mph).
• Accuracy 0.5 m/s (1 mph).
• Update time 2-5 sec.
IMPORTANT!!! Small children should not be given magnets because they may swallow them. If two (or more) magnets are swallowed, the magnets can become magnetized to each other in the intestines, squeezing the intestinal tissues between themselves. This can result in serious injury and hospitalization. Children who already think well (and do not swallow everything in a row) can be given only one magnet, and if the magnet is gone, then you definitely need to find a magnet. Telling children not to swallow magnets is probably not necessary, as this can lead to the opposite result.
For more information, see the Help section in the app.