Old Motor Donates Rotor for Coaxial Wind Vane and Anemometer

Problem: build a combined anemometer and wind vane where the pivots for both sensors are coaxial. Solution: turn an old universal motor into a step-wise potentiometer for the wind vane, and then pull a few tricks to get the whole thing assembled.

commutatior-with-series-resistorsWe have to admit that when we first saw [Ajoy Raman]’s Instructables post, we figured that he used a universal motor to generate a voltage from the anemometer. But [Ajoy]’s solution to the coaxial shafts problem is far more interesting than that. A discarded universal motor donated its rotor and bearings. The windings were stripped off the assembly leaving nothing but the commutator. 1kΩ SMD resistors were soldered across adjacent commutator sections to form a series resistance of 22kΩ with taps every 1k, allowing 0 to 2.2V to be read to the ADC of a microcontroller depending on the angle of the vane.

As clever as that is, [Ajoy] still had to pull off the coaxial part, which he did by drilling out the old motor shaft from one end to the other using just a drill press. The anemometer shaft passes through the hole in the shaft and turns a small DC motor to sense wind speed.

There might have been other ways to accomplish this, but given the constraints and the low cost of this solution, our hats are off to [Ajoy]. We’re a little concerned with that motor used for the anemometer, though. It could result in drag when used as a generator. Maybe a better solution would be a Hall-effect sensor to count rotations of a hard drive rotor.

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Solar-powered Weather Station Has the Complete Suite of Sensors

There was a time when getting weather conditions was only as timely or as local as the six o’clock news from the nearest big-city TV station. Monitoring the weather now is much more granular thanks to the proliferation of personal weather stations. For the ultimate in personalized weather, though, you might want to build your own solar powered weather station.

It looks like [Brian Masney] went all out in designing his weather station. It supports a full stack of sensors – wind speed and direction, rain, temperature, pressure, and dew point. About the only other parameters not supported (yet) are solar radiation, UV, and soil moisture and temperature. The design looks friendly enough that adding those sensors should be a snap – if fact, the 3D models in his GitHub repo suggest that he’s already working on soil sensors. The wind and rain sensor boom is an off-the-shelf unit from Sparkfun, and the temperature and pressure sensors are housed in a very professional 3D printed screen enclosure. All the sensors talk to a Raspberry Pi living in a (hopefully) waterproof enclosure topped with a solar panel for charging the stations batteries. All in all it’s a comprehensive build; you can check out the conditions at [Brian]’s place on Weather Underground.

Weather stations are popular around these parts, as witnessed by this reverse-engineered sensor suite or even this squirrel-logic based station.