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Sunshine Recorder

For discussion of DIY weather equipment - sensors, accessories, improvements to existing kit etc
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steve
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Re: Sunshine Recorder

Post by steve » Tue 07 Jul 2009 9:33 am

apenwith wrote:I'm starting to feel guilty using so much of Steve's forum !
No problem at all - I'm very happy for the forum to be used for this kind of stuff. Keep it up!
Steve

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hans
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Re: Sunshine Recorder

Post by hans » Tue 07 Jul 2009 10:54 am

another idea again ;)

in astronomy for sun observation,a filter is used ,known as Baader solar foil,which is very cheap.it looks like tin foil(but isn't)

a small piece used as a filter for the ldr might rule out the cloud reflection,it would only see the sunspot on the bulb.
contrast can be sharpened with a yellow filter.

it might even rule out the difference noon sun/evening sun(not sure of that)

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Re: Sunshine Recorder

Post by apenwith » Tue 07 Jul 2009 8:12 pm

Hi
I think that film is used to observe the sun safely and might have too much filtering effect
but thanks for all ideas.
I'm just building a new detector head to try out a couple more ideas.
Results of the biassing by using a second LDR don't look as good as I thought. It is very
difficult to get the resistances to get into equilibrium. Getting the aperture of the south LDR
right to create the right resistance offsets is the problem.
I've had the system working perfectly in daytime sun and perfectly in evening sun but the
settings are just not quite close enough to cope with both as reliably as I'd like.
We'll see what the new ideas produce - I'm hopeful but I might be busy for a day or two.
Thanks again
Alan

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Re: Sunshine Recorder

Post by apenwith » Wed 08 Jul 2009 8:54 pm

Hi
See the pic to see what I mean here.
After a lot of doodling with circles and angles it turns out that only a quite small area of the
bulb/sphere is needed to create the sun spot image on the LDR. Any other light getting in only
weakens the contrast between sun and not sun. So the Mk 5 (I think) version tries to keep
as much ambient light out as possible. The LDR tube can practically touch the base of the bulb
and the bulb itself then keeps out some cloud light. As the bit of the bulb closest to the LDR has
no function in reflecting I've screened the tube window with a 3 cm central blackout. If the LDR can see past the bulb around the edges the 'hat' will give a matt black contrast as well as
reducing any back lighting.
I'm not sure yet how one would adjust for different latitudes but it seems aligning the axis
at 90 degrees to the highest (summer) sun elevation looks about right.
The first trial with evening sunlight worked perfectly with the original very simple circuit. And
manually turning the detector round to represent noon sun worked as well. Sufficiently to justify
taking the mast down yet again and fitting the new version. The sun/not sun changes in the
OPAMP voltage are now in the 1/10th's volt range rather than the 1/100th's so it should be a lot
more positive.
Dare I say it - I'm hopeful !!
Regards Alan
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Re: Sunshine Recorder

Post by beteljuice » Wed 08 Jul 2009 9:24 pm

:P Great Stuff ! - now we'll have to see what differences Winter season makes :lol:

Seriously - good work, sometimes the simplest solution is also the most efficient.

A thought occured to me, we talking about the reflected image, is it possible / likely that the bulbs powder coating is flourescing ?
Image
......................Imagine, what you will KNOW tomorrow !

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hans
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Re: Sunshine Recorder

Post by hans » Wed 08 Jul 2009 10:58 pm

Well done!!

That's a trully DIY.neat and fairly simple.
if you (or anybody)ever can get it via USB and get it into cumulus it would be a great added feature for the station.

would you consider making a step by step "how to make a sunshinerecorder"?
(and for steve; a DIY -section?) :)

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Re: Sunshine Recorder

Post by apenwith » Thu 09 Jul 2009 8:31 am

Hi
I've yet to do proper field tests so we'll have to wait for the proof yet.
I've already got an input to the computer via an old fashioned game port but it would
be simple enough to modify a cheap usb joystick circuit to do the same. What I would need
is a programme that sees a joystick button and relates it to time - presumably to put
the result in a text file that Cumulus could read - no doubt Steve would say what is needed.
What would be useful - yesterday's total or sun so far today ?
So any programmers out there - HELP !
But we're jumping ahead a bit - wait for the tests.
And yes a DIY forum section would be great - I'm sure there are other idiots like me - it's
not just to do things cheaply - it's the challenge.
Regards
Alan

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steve
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Re: Sunshine Recorder

Post by steve » Thu 09 Jul 2009 8:38 am

OK - I'll create a forum section for this; the stuff about home-made screens etc will also fit there. I'm not sure whether to call it 'DIY' or 'Homebrew' - either title has the potential for confusion :)
Steve

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Re: Sunshine Recorder

Post by keithatrochdale » Thu 09 Jul 2009 11:19 am

I think Homebrew would be good hic........ :lol:
Nothing is foolproof, to a sufficiently talented fool . . .

WH1080PC Rochdale UK, 171m

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Re: Sunshine Recorder

Post by apenwith » Thu 09 Jul 2009 8:36 pm

Hi
Day one trial.
Recorded sun from shadows becoming distinct from 1100 hrs to 1700hrs (including Noon sun)
in broken fair weather cumulus with no problems. Then the sky went cirrussy and the sun shine
was enough to create vague shadows but with little heat. The recorder was not too happy
on the daytime settings and started a bit of an on/off cycle. I imagine Campbell Stokes would
have a problem here so I'm not too bothered as this sort of cirrus is not too frequent. I could
adjust to cope with the cirrus but it might compromise the daytime recording.
So far I'm pleased but I'll give it a few more days before declaring any success.
The 'hat' was a bit of an afterthought and on reflection would have been better with a smaller
diameter closer to the sphere of the bulb (bit more wind proof).
Getting the results into the computer doesn't present too much a an obstacle but a wireless
link is way outside my experience - any thoughts ?
Regards Alan
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Re: Sunshine Recorder

Post by hans » Thu 09 Jul 2009 9:06 pm

since the signal is only on/off,could something like this be used?
Image
(not on 110/220v,but also adapted to 5V,its inbuild circuit should have some transformer in it)

connect the relais of the sunshinerecorder with a remotebutton,and the receiver to some sort input in the pc(maybe a modified mouse(usb) button)
and catch that mouse signal to a script(way over my head)without it interfering with the normal mouse.

(i only have usb,no serial or paralel on my laptop)

i think this sunshine meter is far more beter than the Campbell stokes,that also has to produce some heat, at least it needs some seconds to heat the paper,a bit of wind would cool it already ,this one reacts immediatly to the sunlight.


thanks steve, Homebuilt says it all.

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Re: Sunshine Recorder

Post by apenwith » Mon 13 Jul 2009 8:02 pm

Hi
After two days of rain and no sun at all we've had a couple of days with a mixture. Perfect for
testing. The system is still not quite coping with the last hour of the day (and probably the
first - but I'm not up that early). I'm not too sure of the reason - probably the sun is not quite
bright enough. The rest of the time everything is fine - timing down to just a few seconds.
More thinking to do !
Regards Alan

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Re: Sunshine Recorder

Post by apenwith » Wed 15 Jul 2009 7:33 pm

Hi
Been a bit busy - haven't given up !!
The dawn/dusk problem seems to have been solved by mounting three LDR's in the base of the
LDR tube - one centre and one each at the east and west edges. All connected in series.
Hopefully it is not going to cause a daytime problem - tomorrow will tell. I'd be interested to
know what kind of accuracy is achieved by Cambell Stokes etc. particularly when there is
patchy cloud with a lot of sun/no sun changes and at dawn/dusk. Maybe I'm trying to get an accuracy that is not even achievable with expensive gear.
Regards Alan

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Re: Sunshine Recorder

Post by apenwith » Sun 19 Jul 2009 11:42 am

Hi
I'm still playing - the three LDR set up looks good - it works down to the last 20 minutes or so of
the setting sun. I didn't have the LDR tube close enough to the bulb at first and it did allow
bright cloud light to start the stopwatch but having corrected that we seem to be close to
something worthwhile. Apparently Campbell Stokes is only about +/- 10% accurate and
overstates when there is quickly intermittant sunshine (I guess the burn marks are too close
together). I think I can claim to be close to that accuracy but short of sitting all day with a
stopwatch I'm not sure how I can prove it. There are probably few people with a horizon to
horizon viewing site so if you want a good indication of sunshine hours I reckon for 20 odd
pounds (UK) this could be the answer.
I would still like to hear from any programmers who could relate the input (there are some USB
interface circuits for about 25 pounds or a scrap joystick) to time.
Regards Alan

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Re: Sunshine Recorder

Post by lordgoata » Sun 19 Jul 2009 4:06 pm

Hehehe this is way cool :-) I love things like this!

I will ask one of our hardware engineers/programmers at work tomorrow if he has any ideas (if he has time) about getting the input into the PC. No promises, but I'll see what he says.

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