Wind speed indicator

Peter KG6LSE · 2011-04-21 12:21

I am a storm spotter and I really wanted to make my own instruments to help with My spotter duty's .
I made last week a lightning trigger ( post soon ) and yesterday I made my WSI .

Its a Simple Idea that came from the 10 Surplus computer fans I had donated to me by a friend .
I said . Hmm maby I can use them in reverse ...

Well not Quite but I can use the Coil and some outside parts to dive a µCU for data logging or what not .

There are 2 ways to sense the speed . Voltage and PPS ( Hz ) .
And 2 sensors .. The coil and the Hall effect .
The hall is Ok but I did not find a pinout for it nor was I able to reverse engineer where the pins went Besides the GND .

So I decided on the coil .
There are 2 coils in the fan I gutted . they are in series .
I only need one . As the 2ed is out of phase anyways .

so I ran wire from it to a meter and spun the fan .. 1.9 V max .

Ummm not what I wanted ..

I tried the RCTIME on the BS2 but No Joy so I decided to do PPS . Well the sig was not registering at low RPMs( 200mV go figure) so I added a amp as a comparator . LM741 .

Now I get clean GND to RAIL swing and I can use it with a µCU .

I used some super simple code

CPS VAR WORD 
DO 
COUNT 2,1000,CPS
DEBUG DEC(CPS),CR
LOOP

To put it on screen and I added my Meter that can read FREQ and DUTY and both numbers Jive so I was pleased.
I am adding some Egg cups ( tis the season ) to the arms

Now I need to CAL it with a real one OR a car :cool:

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Enjoy

Peter

ElectricAye · 2011-04-21 20:58

Peter KG6LSE wrote: »

...
I made last week a lightning trigger ( post soon )...

Any idea how you can make a lightning sensor that can display a map (or at least directions) of recent lightning strikes in real time? I've seen such devices but I don't know what they're called or how they work.

Franklin · 2011-04-21 21:00

If it's a standard pc three wire fan the hall goes to the yellow (usually) wire.

Peter KG6LSE · 2011-04-21 22:21

I looked at that and was not able to see a RPM out of any kind .

I too Know of the Tach out that is IDEAL but I had no luck.

EA . I know of a few ways but I am not totaly shure they would work .

TDOA of the RF pulse . but to be Ideal you don't need sub mS delay so a 180* FOV CCD cam with object rec is ideal .

I need to use RF as is more relaible for Omni use and its easy to do .
But I have seen a few Photodiode based ones for SLR use

with a CCD it is bitmap and a Prop chip Ill bet wil do the job well .. but the exact way I am not shure .

Peter

ElectricAye · 2011-04-21 22:39

Peter KG6LSE wrote: »

...

I need to use RF as is more relaible for Omni use and its easy to do ....

An optical system using IR sounds interesting, but I was wondering how it's down with radio freqs. And what's such a system called?

kwinn · 2011-04-22 11:40

ElectricAye wrote: »

An optical system using IR sounds interesting, but I was wondering how it's down with radio freqs. And what's such a system called?

It's called an rf direction finder, and it is done with 2 circular antenna coils mounted 90 degrees apart. If you watched WW2 movies you may have seen them mounted on a vehicle roof. Essentially the signals from both antennas are compared to give a direction, but only 0-180 degrees. The signal could come from in front or behind. For lightning detection you could combine the antenna with 4 or more photo detectors to give a more precise location.

ElectricAye · 2011-04-22 12:11

kwinn wrote: »

...The signal could come from in front or behind. For lightning detection you could combine the antenna with 4 or more photo detectors to give a more precise location.

That's a very interesting idea. But it seems the units I saw ~20 years ago could display not only direction but distance, too. They were used on small airplanes and I think they had 4 antennae, so I just guessed maybe they used some sort of nanosecond timing system, or phase shift or whatever. On the other hand, maybe they just estimated distance based on signal strength and the system presumed the lightning is coming from the front. I wonder how far away an IR detector can pick up lightning during rainy conditions, and how easy it would be to test for that.

thanks!
:-)

kwinn · 2011-04-22 21:33

ElectricAye wrote: »

That's a very interesting idea. But it seems the units I saw ~20 years ago could display not only direction but distance, too. They were used on small airplanes and I think they had 4 antennae, so I just guessed maybe they used some sort of nanosecond timing system, or phase shift or whatever. On the other hand, maybe they just estimated distance based on signal strength and the system presumed the lightning is coming from the front. I wonder how far away an IR detector can pick up lightning during rainy conditions, and how easy it would be to test for that.

thanks!
:-)

The distance can be estimated by the time difference between the rf or light pulse and the thunder clap. Speed of sound is approx 1089 ft/second in air, and the speed of light is so high it can be ignored. With 4 antennas the direction can be determined for a full 360 degrees by comparing signal phase or timing between antennas so IR detectors are not needed.

Peter KG6LSE · 2011-04-23 20:58

I just posted the plan behind the ligthning trigger here >>> http://forums.parallax.com/showthread.php?131214-Lightning-trigger

Ill have the circuit up some time next week ..( not at home right now ).
Peter

Peter KG6LSE · 2011-04-23 21:07

lightning is arround 300KHz to 4 MHz or so ..... this is the MF and HF band ....... yea a wire loop is way better .

but for clear strikes the CCD /CMOS with a Object Reconition Software is way better if done right.

Peter

Wind speed indicator

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