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Weather Vane

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otm

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Hello everyone,

Lets get started.... I Am currently doing A Level Electronics and am thinking about my coursework. I have decided it would be nice to create a wireless weather station.

Now I need to create the Sensors, I have decided to have an anemometer device (using a motor that when it spins it induces a voltage which is proportional to the speed), a simply humidity probe and a ultra sensative thermistor.

I need help with a vane, I had a thought about using a potentiometer which alters the voltage. However, for this idea I would need a pot which is as frictionless as possible, and can have unlimited turn because the ones college have has got a stopper to stop it rotating fully.

All signal are then put into an AM signal which is read by a receiver box which then useing a computer parallel port and a QBasic iterface....

If someone could help me either tell me about specific potentiometer that would be great... OR... another option which could work...

Cheers,

Owen
 
hi Owen,:)

A three spoked wheel [ at 120deg] with half [tennis] balls mounted at the end of the 6 inch spokes, makes a reasonable wind speed indicator.
Mount a small magnet on each spoke arm and use a reed switch to measure the *3 rotations.

EDIT:

**broken link removed**

Precision Potentiometer Selection Guide

**broken link removed**
 
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Cheers,

Those Precision Potentiometer, would I be looking at the continuos rotation ones?

if I set north at 0 ohms, when it rotated 360 degrees, would the new resistance be 0 ohms,

or are they like the worm screw drives where the 0 degree point is 0 ohms but the 360 degree point is 5k ohm and the 720 degree point 10k ohm etc..

Again thank you for a rapid response,

Owen


PS: would things like this be ok?

**broken link removed**

or

**broken link removed**
 
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continous rotation..

You edited that when I was replying.!!!
 
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Sorry,

Thankyou Very much though you have been a great help...

I've no doubt I will be on this board again soon...

Cheers,

Owen
 
Sorry,

Thankyou Very much though you have been a great help...

I've no doubt I will be on this board again soon...

Cheers,

Owen

Make sure you water proof the pot, keep out the rain.! Good Luck.:)
 
Sorry to rear its head again, but it is still based on this......

Does anyone know QBasic well enough (thats the language we are being taught as part of the syllabus) to help me sort something out (pusedo at the moment!)

I need to take the incoming voltages from the sensors (though ADC, and Buffer) throught the parallel port and use the INP command to then define wind speed, direction, temp humdity etc..

How could I take the incoming voltages and seperate them out so if input = 3volts then, if input = 4volts then do somthing else etc...

I have yet to understand QBAISC well enough to work this out (I will at some point)


Cheers,


Owen.


PS. sorry if not right place to ask this....
 
Did you say Qbasic? Switch to Vbasic, there is much more support on the net.
 
Hi otm,

for the pot check out Beckman Industries. I got two samples of the same pot years ago and used one for the transmitter and the other one for a remote indicator.

Those pots have unlimited mechanical way and 355 degrees of electric angle. At most locations the wind blows from the north very seldom. So I used north as a reference angle for the dead zone.

Boncuk
 
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Yes I did,

Qbasic is taught as part of the A Level Electronics syllabus.......

Which PC operating system are you using, Win XP,,, DOS, Vista.????
 
Which PC operating system are you using, Win XP,,, DOS, Vista.????

Well I run Vista x64 ultimate at home,

But the 6th form have allocated 7 old machines running just DOS with the Qbasic on it in the CDT department...

Cheers,

Owen
 
Cheers I've just read your link and its very intresting, However, They focus more on the Output command.

unfortunatly, I am no closer. I will keep thinking about this.

Thankyou to everyone so far.... If by chance someone has a breakthrough idea feel free to post it.

Cheers,

Owen.
 
Look again. It discusses the INP command.
 
Sorry.. I have a tendancy to miss things when I skim read!

I will need to test this at college during the week because I can't at home, but Im still not sure in my mind how to turn a changing voltage at the same pin into a speed in knots...

If someone knows, how would you do it in Visual Basic, because it can't be too far off...

Cheers,

Owen.
 
Okay, so let's say your weather vane outputs a DC voltage proportional to speed, such as a DC motor with a tach output. This analog signal needs to be converted to digital be it a PIC or discrete analog to digital converter.

You need to know what wind speed equates to x volts. Then you also need to compute x volts equals n binary value.
In other words; Windspeed --> Volts-->Binary number. You now have this binary number sitting all fat dumb and happy at your Pport. With the right hardware interface you write a [variable]=INP([port]) with your qbasic code. The INP command will read your ADC or whatever. You now have a n binary value that your code can use to make a wind speed conversion.

To compute what wind speed equals what volts on your wind vane, you could do a bunch of math. Another way is to take your wind gauge with a multimeter, have someone drive you around in a car at a preset speed while you hold the gauge out the window. When the driver gives you a speed number, say 10 MPH you measure the gauge output voltage with a meter. Do this at a few different speeds, make a graph and interpolate. Bada bing bada boom.

Just don't drop the gauge :)
 
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Sorry.. I have a tendancy to miss things when I skim read!

I will need to test this at college during the week because I can't at home, but Im still not sure in my mind how to turn a changing voltage at the same pin into a speed in knots...

If someone knows, how would you do it in Visual Basic, because it can't be too far off...

Cheers,

Owen.

hi Owen.
I can help with QB and VB5 for controlling the PC's parallel port. [ I would prefer the VB5 route.:)]

I use Win XP Pro and have two DLL's which allow port control, Win XP blocks direct access to the port without these DLL's.
Vista I dont know.

You will require a simple interface on the port output, usually a 74LS06 or 07.

This acts as a buffer for the port and peripherals.
I use the MCP3202 or 3204 dual /quad 12bit adc convertors.
Available from Farnell, get the datasheet from Farnell.

If you are interested I will post details of the PC interface.
The Millenium Tower is due South of my location, about 5 miles.:rolleyes:
 
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hi,
Look at the attached pdf for the PC parallel port.

This image is shows the results I get from VB5 with the MCP3204 circuit.

If you are interested I will extract and post the SPI routines from my VB5 programs.:)

EDIT:
To complete the package a zip file has been added.
Its been stripped down to the bare essentials, tested and works OK.
The two DLL's must be loaded to the users C:\Windows\System folder.
The VB source code and MCP exe file are also in the zip.

Create a folder named MCP3204 and unzipped the zip file to that folder.
.
If you want to run the exe file included in the zip, you must have the Visual Basic 5 runtime files in the System folder.
The smaller image is the stripped down version.
 

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Cheers, everyone..

I am currently reviewing ericgibbs comments (That will take time)

After reading Mikebits if I think Correct.... By passing the output voltage of the windspeed through a discrete ADC It will then turn the analogue input into a digital binary signal that can simply but read by the porgram at the input port

eg. binarynumber$=Inp(&H378) 'variable is equal to the binary input at parallel port

Then binarynumber$ would = 10110 for example which equates the input voltage of 5 volts say.... If the input voltage changes then the binary number is different....

(Im learning this as I go along so if i've made a mistake then can someone please correct me)

Cheers everyone,

Owen.
 
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