This is my homemade digital anemometer. It is made of cups rotating with a magnet triggering a reed switch. The wires are connected to an Arduino Uno that calculates the time between consecutive pulses (after reed switch debouncing by my arduino software)
DHT22 and DS18b20 sensors running on an ESP8266-12 programmed with the Arduino IDE monitor attic conditions and heating/cooling system performance. Over-the-air (OTA) updates are implemented. Power is from mains with Lithium-ion cell backup.