G+_Jason Perry Posted July 9, 2016 Share Posted July 9, 2016 I am thinking of making an anemometer out of a 120mm PC fan. Is it as simple as reading the voltage created from the fan spinning? Link to comment Share on other sites More sharing options...
G+_Robert Gauld Posted July 9, 2016 Share Posted July 9, 2016 Yes but you'd need to work out some way to calibrate it. Also that's quite a large fan so the wind would have to be quite strong to get that much mass moving, try a smaller fan. Link to comment Share on other sites More sharing options...
G+_Tyler Pearson Posted July 9, 2016 Share Posted July 9, 2016 I'm not sure if all fans would work as well but I've never tested since some are variable, 3 or single speed fans. Plus as Robert mentioned you would need a lot of force. You would only be able to get readings from strong winds and would have to figure out how fast the fan spins vs how hard the wind is blowing. There also not as free spinning as typical wind sensors. I did a search and found an arduino dedicated wind seneor but it is $70. If you find a way to Calibrate it maybe try making a free spinning anemometer or by one if those wind spinner things that sit on the roof and hack some type of speed/rotation sensor of some kind to it. Still requires you to Calibrate it but it would work better then a PC fan. FYI I found an instructable about making one. I didn't read it through but it may help you out. http://www.instructables.com/id/Anemometer-on-the-cheap/?ALLSTEPS Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted July 9, 2016 Share Posted July 9, 2016 would be better off reading a hall effect sensor. Link to comment Share on other sites More sharing options...
G+_Jason Perry Posted July 9, 2016 Author Share Posted July 9, 2016 The more I think about it the actual unit of measurement isn't that important, more measuring differences between two anemometers. Link to comment Share on other sites More sharing options...
G+_Jason Perry Posted July 9, 2016 Author Share Posted July 9, 2016 Eddie Foy?, funny you say that the instructables article actually references there is a hall effect sensor in the fans to detect the position of the fan. Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted July 9, 2016 Share Posted July 9, 2016 If you are only looking for a difference between 2, then I'd say as a learning experiment, do NOT use a CPU (arduino, etc) But use straight up TTL/74xxx chips and a clock. Counters, latching registers, etc. Would learn a TON about digital. Link to comment Share on other sites More sharing options...
G+_Jason Perry Posted July 9, 2016 Author Share Posted July 9, 2016 Thanks for the suggestion Eddie Foy?. I'll look at that. My ultimate goal is as compact as possible, so even if I did go with the arduino option I would want to get it down to just the chip and necessary electronics. Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted July 9, 2016 Share Posted July 9, 2016 Compact, then just a AVR/PIC, etc. Just get one with the correct timmers, counters, etc. Read the data sheets for the actual chip. If you are a masochist, you could go the PAL/GAL/FPGA route too. (PAL/GAL would work, FPGA overkill. Link to comment Share on other sites More sharing options...
G+_Robert Gauld Posted July 10, 2016 Share Posted July 10, 2016 Jason Perry yes, my mistake earlier - the feedback from the fan is NOT an analog voltage but is pulses. Link to comment Share on other sites More sharing options...
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