Anemometer and the diameter vs circumference Answered
Various Instructables have been created for building a wind speed anemometer, and nearly all use a bicycle speedometer for the read out.
My question is, regardless of the actual diameter, the sensor can be close to the outer rim, or close to the hub, because one revolution is going to be one revolution and register as such on the speedometer.
So, setting the speedometer to whatever rim size you desire, the readout would be correct.
If you set the tire size to 24", then each time the sensor is tripped, it will show the speed for that tire size. The same with 27" or 28" tires.
The reason I'm asking is because I'm putting together a 'gopher chaser' from Harbor Freight (on sale last weekend for $1.50) which measures 17 3/8".
I have no desire to cut new blades from sheet metal....
Thanks for any input on the issue.