# Allow voltage flow when turning a motor with the wind

Joined Jan 15, 2015
5,934
At what wind speed causes switch.
Any speed does not matter, however we have to consider that it is not much wind speed.
Kind of hard to quantify that but I guess we can assume that the actual wind speed as measured with for an anemometer is not really necessary, only if there is any wind (a breeze) present or not. While I liked just suspending a magnet over a magnetic reed switch I have seen methods as simple as gluing a small cardboard tab to a toothpick and gluing that to a lever actuated micro-switch.

I guess if the thread starter wants to return with more information there can be more ideas and methods suggested. Beats me?

Ron

#### Tonyr1084

Joined Sep 24, 2015
5,992
"At any speed"? There's ALWAYS wind at "any" speed. That's why I said we can assume there's wind because no air mass remains stagnant. "What wind speed" is not only a valid question, it is a crucial question.

#### Tonyr1084

Joined Sep 24, 2015
5,992
2 weeks only
This has to last only two weeks? OK, I'm lost in trying to understand why this is even a project. Unless you're a crane operator and can't use a crane above certain wind speeds. But in that case, cranes have wind speed detectors on them already.

You may not wish to disclose the nature of the project, but can you at least address two issues: The wind speed you want to detect and why it has to work for two weeks?

#### mosco_dj

Joined Apr 11, 2019
6
Thank you very much everyone for your suggestions, I have tried several and so far there are 2 that I will cite below that have worked more or less properly.

Overall, I know I didn't describe the project much, but I think most of you got the idea.

When I refer to "it doesn't matter how much wind there is," I know that there is always wind, but enough wind to make the motor's propeller move is what I would detect.

The motors would not be connected in series, it is a LED for each motor, in total there would be 320 motors with 320 LEDs, installed in different places. The LED will be just 10cm from the engine, only behind a false wall.

Thanks to all again!

#### mosco_dj

Joined Apr 11, 2019
6
You could fix a small magnet to the bottom of a curtain (e.g. a strip of cling-film) and have a reed switch near the magnet.
This is one of the ideas that I have prototyped, apparently it will be the chosen one, I just have to find a better position of the switch. Thanks a lot for the suggestion!

#### mosco_dj

Joined Apr 11, 2019
6
How much air flow do you need to trigger?
Another type of airflow detector uses 2 small thermistors (both exactly the same type). One is shielded from the flow (but exposed to the air), the other is in the flow. They are both self heated using a small current. Actually they can be connected in series so that the current is guaranteed equal. When the one in the airflow is cooled by the moving air, its temperature reduces (compared to the other one), and its resistance changes.
Two thermistors are used to null out the affect of ambient temperature.
Good thing about this system is that there are no moving parts and the output is directly a voltage. They need to be small for quick response and small heating current.
This is the other idea that I have prototyped. In the city where I live it has worked well, but I am afraid that where the project is installed it will not work the same, since it will be in a place that has very high temperatures and I do not know if the wind speed (in a hot and humid place) is Enough to activate the difference.

#### Bernard

Joined Aug 7, 2008
5,788
One more : A vertical 1 ft. section of music wire forms one connection the other it a wire loop about half way up. There is a wind catching vane on top. A charge integrator lights LED on short hits, solid on with steady wind. Electronics, inc. LED, about US $.45. If only steady wind counts, cost about US$ .15 resistor & LED.

#### MisterBill2

Joined Jan 23, 2018
8,787
The real challenge will be producing 320 devices with similar sensitivity, and doing it at some small cost.
And given the "top secret" unstated information level, that we get no real description of the area of this collection of sensors, are they in some sort of array, or what?
This could be some sort of special effect for a video production or show, or an array of triggers for a mine field. Or some sort of secret scientific research.