Sandaysoft

I finished my Stevenson Screen last night and thought I would take a few
photo's of it for you all to see.

As you can see on the second to last image, I had managed to split
one of the trays when i was cutting out the hole for the fan.

I may buy a new one at the weekend and replace it.

Also I painted the trays with White Gloss paint I had kicking around
in my garage, but on second thoughts I think I should have primed
the trays 1st as I think the paint may peal off. I will have to wait and see.

Also I took the solar fan outside yesterday evening (rainy overcast conditions)
and tried it out. At 1st it did not spin up, until I blew on the fan blades then it started
working. But when I put my had over the solar panel it stopped working, as expected,
and when I took my hand away, I had to blow on the blades to get it started again.

Now I am unsure whether it will start to spin up on its own.
I just wonder if it did not start on its own due to the conditions being
overcast? and not bright sunlight, as I dont fancy having to go up and
blow on the fan each morning

_________________
Cumulus Real Time Data Grabber
http://bit.ly/WjBh5z

Wokingham Berkshire - weather station
http://www.wokinghamweather.co.uk

MRD Photography
http://www.mrdphotography.co.uk

Thanks for the pics. Good job. Its coming into summer for you in the northern hemisphere and I'd reckon it will spin up on its own

_________________
Dan

http://www.brisbaneliveweather.com



A man with a thermometer always knows the temperature. A man with two thermometers, not so sure.

That looks fine I don't think the crack will be any problem. Seems the fan wont work without good light, maybe sunshine but since it's sunshine that causes the temperature rise problem, I don't see any worry there either. I suggest checking every few months or so that the fan is still working in sunlight - they can sometimes gum up.

_________________
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

Great Pics Solorize
solar Fan looks very nice probably just needs a good bit of strong sunlight to get it moving

My Sensor is in the shade most of the day until about 4pm at this time of year
so by the time the sun gets round it`s pretty low in the sky anyway

Managed to get a meter of 6mm threaded rod from local hardware shop for £1.25
And have just ordered 6 of these 20cm x 5.5cm melamine bowls for £9.69 inc pp
May add some sort of solar fan at a later date if needed but would need to be able to angle the panel at 45deg
Thought about modding one of these available on Amazon for about a fiver

_________________
Roy
CWOP: DW6272
WUnderground
RadstockWeather on Twitter
Met Office Wow Site

That is really nifty. I bought my solar shield so I missed out on the quest to build a better one. Mine is okay but not as good as y'all's.

Randy

_________________
Georgia Home Orchard

http://georgiahomeorchard.blogspot.com/

Hi,

Yes, the solar cell may well need direct sunlight to overcome the "stiction" (static friction) of the motor. Also, I think most dc motors now use an "electronic commutator" which requires sufficient voltage to activate the circuitry.

Solar-powering the fan seems a very neat idea. My only (slight) concern is that the heating effect is primarily due to infra-red light, but solar cells are optimised for visble light (towards the higher-energy green-blue end of the spectrum?). I wonder if there are any weather conditions when there is too much of the former and not enough of the latter?

I presume the fan unit from Amazon is this one. The diameter is quoted as 6 cms (is that the fan blades or the "guard") so the solar cell looks quite small, perhaps 20 - 30 sq cms? It will probably run with normal, full sunlight but I doubt if with anything much less.

However, in keeping with FO's "Cheap and Cheerful" approach, I've been looking at the possibility of using the cells from a few solar garden lights and maybe a "notebook cooler" fan, all from a "Pound shop". The cells very probably will not deliver sufficient power to start up the fan, so my solution is to store the energy in a capacitor, with simple control electronics to kick the fan into life when there is sufficient voltage. I'd hoped to use a "super capacitor" but sadly these appear to have too much Effective Series Resistance. But a small bank of normal low-voltage electrolytic capacitors seems to be just about viable for a small motor. In bright sunlight the motor might keep running, but my theory is that brief "puffs" of air may be sufficient to keep the internal temperature moderately accurate?

As an extension of this, I've wondered about using rechargeable batteries so that the fan could give occasional puffs of air even overnight. Does anyone think that such a mode actually would be beneficial?

Cheers, Alan.

I've tried trays painted with paint. Trouble is that the paint will flake eventually - thats why I use white melamine bowls now - these should last for a very long time and be resistant to weather and durable. However I have painted the underside of the inside of the bowls (except for the bottom one) matt black as some professional screens do likewise.
The fan should start with brighter sunlight. A certain current is needed to start the fan.

Trev

I used "straight onto plastic" white spray paint for the plastic items.

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Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

Here are a couple of different products for spraying onto plastic
http://www.plasti-kote.co.uk/Product/pcode---4181
http://www.amazon.co.uk/s/ref=nb_sb_nos ... nt&x=0&y=0
Personally I agree with Teg melamine is the way to go

_________________
Roy
CWOP: DW6272
WUnderground
RadstockWeather on Twitter
Met Office Wow Site

I used the plasti-kote paint on an early prototype using plastic trays - result the paint flaked.

Trev

You might need a few more of these bowls. The screen needs to be able to shield radiation from any angle and the trick is to space the bowls such that the temperature sensor is not visible even looking from below. You need to make the central hole in the bowls as small as possible and experiment with spacing of the bowls to enable this. Melamine is hard to cut - do not use a normal drill. I found that a glass cutting drill worked well. I drilled out the central hole using a circular saw mounted in a drill.
Where did you get the bowls from? I found them difficult to source.

Trev

Here is a link to the ones that i have ordered, Works out at £1.61 each inc pp
http://www.amazon.co.uk/gp/product/B001 ... ss_product
Also there are some on ebay
http://stores.ebay.co.uk/Bob-Elles/Mela ... 34.c0.m322

PS. if you leave out the fine-offset shield you could getaway with a 42mm hole as the transmitter is 42x25mm
Not sure if there is any benefit of having 2 shields in place !!!

_________________
Roy
CWOP: DW6272
WUnderground
RadstockWeather on Twitter
Met Office Wow Site

You definitely will not need the fine-offset shield.

Trev

A quick update on the Solar fan, after reading peoples replies.

I took it outside again this evening and stood in the centre of my garden
and it started to spin on it's own

I think that when I tested it yesterday I was too near my
house and it may have been blocking the limited suns rays
at that late time of the day.



I decided against Melamine bowls as I was unsure how to cut-out a Dia 130mm hole in the top most
one that I would have to attached my solar fan to, so went for the plastic trays. If the paint starts to
flake off, then I may have another look into Melamine bowls.

Btw. Does anyone know how the best way to cut a Dia 130mm hole in Melamine would be?

_________________
Cumulus Real Time Data Grabber
http://bit.ly/WjBh5z

Wokingham Berkshire - weather station
http://www.wokinghamweather.co.uk

MRD Photography
http://www.mrdphotography.co.uk

Perhaps a 'Dremel' and a steady hand.

_________________
Dan

http://www.brisbaneliveweather.com



A man with a thermometer always knows the temperature. A man with two thermometers, not so sure.