If you use a magnet on the anemometer you will need to balance this. If you have a 3 pronged anemometer (ie 3 cups on arms) then you would typically need 3 magnets to keep it balanced nicely.
Otherwise you will need a large centre ring with a magnet, balanced with weights.
I like the idea of having a coil that the magnets pass over causing a current spike. Turn this into a voltage, and you can feed this into a prop pin via appropriate resistance. Protect with a zener if necessary.
I found a small USB powered fan that looks like it will fit what I need perfectly....and it only cost $10. Already got it taken apart and about to glue the magnets to the drum where the old magnet strip used to be. Total cost will be about $15 for everything unless I run into a problem.
We did this (a long time ago) just using a thermosistor.
No notes though...
The appeal of thermistor approach is no moving parts.
Downsides are the need for an exposed thermistor (in the wind, but out of the sun/rain/snow), which tends to be fragile and not very cheap.
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Simplest thermistor designs use a DC power injection to maintain some fixed 'C (ie fixed decrease in R)
That needs ambient tracking, which can be a second thermistor, but ideally that is also remote, close to the exposed one, but out of the wind flow.
Or, you can pulse the single thermistor and measure the slope of the resistance changes.
I'm not sure how thermistors tolerate continual thermal cycling at measurement speeds.
A thermistor will also not catch wind gusts as well as a more direct mechanical approach.
Comments
No notes though...
Otherwise you will need a large centre ring with a magnet, balanced with weights.
I like the idea of having a coil that the magnets pass over causing a current spike. Turn this into a voltage, and you can feed this into a prop pin via appropriate resistance. Protect with a zener if necessary.
The appeal of thermistor approach is no moving parts.
Downsides are the need for an exposed thermistor (in the wind, but out of the sun/rain/snow), which tends to be fragile and not very cheap.
.
Simplest thermistor designs use a DC power injection to maintain some fixed 'C (ie fixed decrease in R)
That needs ambient tracking, which can be a second thermistor, but ideally that is also remote, close to the exposed one, but out of the wind flow.
Or, you can pulse the single thermistor and measure the slope of the resistance changes.
I'm not sure how thermistors tolerate continual thermal cycling at measurement speeds.
A thermistor will also not catch wind gusts as well as a more direct mechanical approach.