Anemometer

thingiverse

This is an anemometer model. It's designed to be mounted to a stick. - The rotation speed can be obtained by a light barrier that's interrupted four times per rotation. - I salvaged the light barrier PCB from a computer mouse, but any PCB-mount light barrier can be soldered on perfboard and mounted. - The rotor is mounted with a 70mm M6 bolt plus nut. This bolt is held on its axis with two 19mm ball bearings. - On the bolt, the interrupting part for the light barrier should be fixed with M6 nuts. - Additionally, there's a place for mounting screw terminals to attach a cable to the processing electronics. - The shovels can be shortened if needed. - All case parts can be screwed together with M3 bolts. The basic operation was tested with the circuit in the picture and an oscilloscope. On the scope captures, it's clear that the ridges created by the printing process in the interrupting part have an effect on the remaining light going through the light barrier and therefore on the quality of the signal. This can probably be improved by printing the interrupting part in black PLA. Anyways, the output signal should be properly processed by a Schmitt-trigger circuit before being fed to a microprocessor. Code and hardware to make use of the signal can be found on https://github.com/stonetronics/stoneWind Update November 2020: After having the first prototype hanging in the wild for half a year, I've iterated the design of the anemometer sensor and reprinted it for the next test. First thing to notice was that the now-black interrupter part creates a much cleaner signal; it's basically a sufficient 5V digital signal. Still, the hardware to condition the signal and measure the output of the sensor has been built and will be programmed. Changes in the Model: - Bigger, with only three shovels. - Interrupter with eight interruptions per rotation. - Additional slits in the bottom of the sensor case to better get rid of water and mist in the sensor case. - More stable hub and roof. - Print in black at least the interrupter. Additionally, I've added a model for a special PCB spacer that's used to mount an SD card to the Arduino shield that can be found on GitHub.