# Allow voltage flow when turning a motor with the wind

#### mosco_dj

Joined Apr 11, 2019
6
Hello everyone and happy new year!

Is there any way to use a conventional 3-6v motor as a switch?

The idea is to put on the tip a kind of "spin", which when winding outside, for example, turn on a LED inside, indicating that there is wind.

I think the most complex part is because they are not strong winds, therefore the motor does not spin at high speed.

First I thought about using a transistor as a switch, but the voltage received by the motor is very low and I don't get a constant light.

It should be noted that it is possible to use a 5v source to power the LED, that is, I do not require the motor to function as a generator, only as a switch.

Another thing that occurred to me is to use 2 transistors, one as a switch and the other as an amplifier, but I get the same result as placing only one as a switch.

It is important that the design be as basic as possible, since I need to install 300 of these motors with their respective 300 LEDs, so the use of sensors and arduinos is ruled out.

Surely someone of you can help me since my knowledge of electronics is scarce.

Thank You!

#### Bernard

Joined Aug 7, 2008
5,686
At what wind speed causes switch.

#### MrChips

Joined Oct 2, 2009
22,096
Don't use a motor. There is too much friction in a motor.
Find or make yourself a propeller that easily turns in the wind.
Then use an optical interrupter to detect motion of the propeller. This will give you a mechanism with almost zero friction and it will turn with any wind. You can use the signal from the optical switch to derive a wind speed.

This is how anemometers are designed. Some of them us a magnetic sensor instead of optical sensor.

#### mosco_dj

Joined Apr 11, 2019
6
At what wind speed causes switch.
Any speed does not matter, however we have to consider that it is not much wind speed.

#### Bernard

Joined Aug 7, 2008
5,686
With a small motor, CD spindle motor, RF-300-FA-12350, very low un powered torque, est. .1 V @ 3MPH wind. US $.89 to$ 6.00. Comparator for V det. & LED driver. My 1975 anemometer used 3 Jello mold cups, magnet & reed switch; the cups are still spinning a decoration.
What is the life expectancy of project ?

#### mosco_dj

Joined Apr 11, 2019
6
With a small motor, CD spindle motor, RF-300-FA-12350, very low un powered torque, est. .1 V @ 3MPH wind. US $.89 to$ 6.00. Comparator for V det. & LED driver. My 1975 anemometer used 3 Jello mold cups, magnet & reed switch; the cups are still spinning a decoration.
What is the life expectancy of project ?
2 weeks only

#### Bernard

Joined Aug 7, 2008
5,686
Be aware of false ON with no wind, like a vane stopped in slot. Might need something like AC coupling ?
Maybe a cheap Savanous ,SP ?, wind wheel made from 3 vertical half cans, Al beer, & one can with no top
but with a dimple in bottom supported on a sharp pointed shaft.
Must run.

#### Alec_t

Joined Sep 17, 2013
11,744
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.

#### Marley

Joined Apr 4, 2016
369
If you use a small DC motor, the output voltage (with no load) will be proportional to speed.
However, with a brushed motor the output will be pulsed due to the commutator. So you will need a filter - could simply be a capacitor. Then a voltage detector. A comparator with a variable threshold.
Or you could try simply connecting a red LED across the motor terminals. How fast does it have to spin to light the LED?

#### Janis59

Joined Aug 21, 2017
1,232
The same task may be realized even with just a slope mounted tail. Make a tail strong fixed to the turbine and heavy stearing plate in the tail. The optimum lift angle is 10-15 deg. Thus, in small winds the propeller area wins thus it is rotating. In very strong winds the tail area creates the force competing with propeller drag, thus the rotator is gradually turned out off the air-stream until the excessive strong winds it is 90 deg across the wind. The critical speed may b set as well with the tail area, or tail angle, or tail weight. Thus the weight is most easy factor where hanging on/off some kilograms the machine may be adjusted to react as it must be.

However, it You are strong cycled-on toward electronics solution, just let measure the generator`s given frequency. If it is AC capacitative async or AC sync generator, its elementary. If that is DC generator, anyway there are some high freq "scratches" on DC voltage curve (when brush is sliding off or on the pads) by which to measure frequency after mild integration and proper amplification ought not be difficult.

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#### Janis59

Joined Aug 21, 2017
1,232
Find or make yourself a propeller that easily turns in the wind
This is how anemometers are designed.
The any sort of anemometer except the sailor sea-vesel designed for, are rather short-life products. If my yacht have an anemometer for several thousands of coins capable to work decades, the pocket anemometer for some 20 or 30 coins (China) have resource of maximum 50 work-hours. So, the potentiometer (or sector opto as the best) with heavy shovel what lifts up in strong wind and sinks in the shallow wind (of course on rotable pole) is the most reliable solution for straight measurements. Or ultrasound Dopler-effec measurers as the ultimate reliable and most precise products in the market, but the price.

#### MisterBill2

Joined Jan 23, 2018
7,306
The TS mentioned needing to make 300 of these systems, so a lot of the ideas fail.
But there is no description of how far between the sensor and the LED, or how accurate these need to be. In fact there is not much description at all.
So the TS needs to provide a lot more details and then the brains can provide more than random guesses. Until then, all that is given are indeed random guesses.

#### Bernard

Joined Aug 7, 2008
5,686
One anemometer ready when the glue cures, beer cans, cardboard, flat black paint, Al foil, & coat hanger- on the cheap ?
Reflective sensor might be Optek, K2362 for testing. Out of stock.

Joined Jan 15, 2015
5,667
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.
For a very basic and inexpensive approach this is what I would be thinking. Doesn't get much simpler or inexpensive.

Ron

#### ConstructionK88

Joined Jul 25, 2018
257
If most transistors base voltage is .7v and assuming but confident that any speed with a wind spun dc motor at a "feelable" breeze should work? Especially if TS is going to use so many of them. I think with that amount hed need a way to reduce the voltage even if some didnt spin and added resistance to whats produced. I once used a 12v drill motor with a box fan blade to electrolize water for hydrogen/oxygen production to power a small burner and lamp in a little shed i made when i was like 12 or so. granted it was on a 30ft pole though.

#### Bernard

Joined Aug 7, 2008
5,686
A small variation of @Alec_t s curtain would be a string with a wind obstruction & magnet on the end with a form B, NC
reed switch below. No wind, LED off, light wind LED might flash, steady wind LED on.

#### Marley

Joined Apr 4, 2016
369
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.

#### Lo_volt

Joined Apr 3, 2014
123
I'm thinking something like the tilt sensor on a pinball game would work well. These were made with a pendulum suspended through the hole in a metal plate. When the pinball machine was tilted too far, the metal rod of the pendulum would make contact the edge of the hole completing a circuit, triggering the tilt relay and shutting down the game.

One could use a whip antenna through the hole in a metal plate with a small "sail" on the top of it to catch the wind. When the wind blows, it would push the antenna up against the plate. The "sail" could be anything attached to the antenna. My first thought was a fairly light foam ball. It only needs a decent profile to pull the antenna with the wind. It would also need debouncing as the contact is likely to be intermittent.

It could also be done with a pendulum but the antenna idea seems like it would be easier to accomplish to me. The plate would be best if it were stainless steel so as to avoid problems with corrosion inhibiting electrical contact. Sensitivity could be adjusted by changing the size of the hole and moving it up or down along the whip.

#### Tonyr1084

Joined Sep 24, 2015
5,239
A ring and a pendulum. The wind blows the pendulum in ANY direction and the shaft of the pendulum contacts the ring, completing a circuit. Given the nature of wind that can blow then subside you can add into your circuitry a memory (capacitance) to hold a light on for a few seconds beyond the wind drop-off.

I can't imagine what you might have as a goal. My only experience has been to use a similar idea consisting of a vertical mounted spring with a weather vane on top. If the wind blows - that spring would lean over and contact a ring switch that would disrupt the launch power to model rocketry. Larger vanes would gather more wind energy and thus, at lower wind speeds, the switch would activate. Smaller vanes would require greater wind speeds. Also, the length of the mount (or pendulum) would affect sensitivity.

If you want to detect wind - just assume there's always wind. After all, no air mass remains stagnant. But if you have a goal of detecting at X wind speed or higher - then my option of a pendulum will give you that capability. An adjustable set of vanes (up or down) on the pendulum will change the sensitivity.

#### Tonyr1084

Joined Sep 24, 2015
5,239
A string tied between two points with some sort of vane in the middle. One end of the string is tied to a solid mount while the other is connected to a micro switch. Tug the string and you tug the switch.