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Sunshine Recorder

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

Post by hans » Tue 16 Jun 2009 6:43 pm

this looks more easier to do.
http://www.instructables.com/id/Cheap%2 ... ght-Probe/

at least you can measure the change in current,which is what is needed here.
(sun/no sun)

apenwith
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Re: Sunshine Recorder

Post by apenwith » Tue 16 Jun 2009 7:27 pm

Hi
Thanks for the suggestions. Data loggers might be the answer.
I think the problem with using a current evaluation is knowing at what point you say the sun is
shining . I think you get into the realms of complex algorithms. My simple solution leaves the
calibration to the electronics. It is fairly simple to adjust the light level to the point where
shadows just start appearing. I have found that when the sun is low the detector is not quite
so sensitive and I've tried biassing the control voltage with a second LDR. Time will tell.
I found someone who wrote a program which times the laps on track car racers using a
photo cell as a switch as the cars pass and connecting this to the game port. I have asked him
for advice as my need is similar - the elapsed time while the switch is on (or off).
I believe pins 1 and 2 on the game port connect to a joystick button so I need software which
detects this and allocates a time from the system clock.
Thanks again and in advance for any suggestions.
Regards
Alan

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hans
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Re: Sunshine Recorder

Post by hans » Tue 16 Jun 2009 8:31 pm

i have seen that page with the track counter
here is how you connect the sensor to the gameport
http://www.epanorama.net/documents/joys ... emperature
for software maybe the mentioned "joystick test program"

this would be nice,sadly it is shareware,but it supports a gameport
http://www.myzips.com/software/Virtual- ... -Pro.phtml

maybe this will help you further

ps
with this you can finetune the sensor
http://www.uoguelph.ca/~antoon/circ/actrelay.htm

apenwith
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Re: Sunshine Recorder

Post by apenwith » Sun 21 Jun 2009 5:47 pm

Hi
Another step in the sunshine recorder saga.
I found a nice program called virtual stopwatch pro by springcreeksoftware which has a start
stop facility operated by a joystick.
My local computer engineers had a sound blaster sound card with a gameport which they gave
me (fortunately XP has a driver for this) . I then made a pseudo joystick from the cable of an
old gameport stick I had lying around.
The wiggly bit of the stick operates variable resistors and these make the computer recognise
the circuit as a joystick. SO I cut off the cable and checked each wire to the pinout of the
plug - and here I add a note of caution - make absolutely sure the meter probes touch only the
right pins or it could all go bang. Sorry I hold no responsiblity for the circuit but I have made it
and it worked for me. Using a small bit of perforated board attach pin 1 via a 100 millamp fuse
to wires from pins 3 and 6 preferably with a resistor 50 to 100 K to each. The attach pins 2 and 4 lead to flying leads which will attach to the normally off contacts of the relay on the recorder circuit. (Velleman/ Maplin light sensitive switch).
I found initially I could not open Control panel/Game controllers but by disabling HID compliant
device under Human Interface Devices I could use game controller to set up a 2 axis 2 switch
joystick.
I think I've reached my post limit - more to come - Alan

apenwith
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Re: Sunshine Recorder

Post by apenwith » Sun 21 Jun 2009 5:54 pm

Continued
Virtual Stopwatch Pro (very reasonable cost) now sees the relay as the joystick stopwatch
starter/stopper. Various reports can be exported to MS Access (except my version is too old)
as well as built in reports. I shall be asking the author if the program could export a total
stopwatch count at say 2355hrs. I'll let you know
Sorry about the length of all this AND be careful if you try the wiring.
Regards
Alan

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Super-T
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Re: Sunshine Recorder

Post by Super-T » Mon 22 Jun 2009 11:27 pm

I used an LDR to auto switch house lights years ago but found that the adjustment would drift with age and I have replaced it about 3 time in 15 years. I guess the weather stations won't last that long anyway :-) Compensation with a 2nd LDR in a bridge would probably fix this.

apenwith
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Re: Sunshine Recorder

Post by apenwith » Thu 25 Jun 2009 3:14 pm

Hi
Trials with the mini detector head were not as successful as I'd hoped. The spot of light
reflected was a bit too small to operate the LDR reliably, particularly when the sun is low.
So it's back to the bigger bulb but (hopefully) a bit more elegantly. I've built a new light
sensitive circuit from the same kit (Maplin - Velleman MK125) and put it and external
potentiometer (100K) rather than the tiny board mounted one, with another 10K pot in series
to ground as a fine tuner. Final mod was a switch to activate the clock if the computer is off.
The pseudo joystick/stopwatch is working well though I haven't found a way of automatically
exporting the daily totals.
While I had the mast down I tried a tail on the wind direction vane. Only tape stiffened with
a couple of plastic strips.
Trials continue. Judging by the number of 'views' I guess there is a bit of interest so I'll let
you know the further progress.
Couple of pics attached
Regards
Alan
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beteljuice
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Re: Sunshine Recorder

Post by beteljuice » Thu 25 Jun 2009 8:42 pm

Please keep your updates / observations coming ;)

If it were easy it wouldn't be "fun" :?
Image
......................Imagine, what you will KNOW tomorrow !

apenwith
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Re: Sunshine Recorder

Post by apenwith » Fri 26 Jun 2009 3:46 pm

Hi
Having got the detector circuit fairly closely tuned this is the sort of records Im geeting on the
stopwatch log. Timed over about five hours with broken cumulus cloud travelling in a 7mph
(by my station - more at cloud level - maybe 200ft). Also a screenshot of the stopwatch
(bottom right) against a pic of my mast. Surpising how many times the sun pops out. There's no
timestamp on the log but I don't think that is useful anyway.
Regards
Alan
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apenwith
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Re: Sunshine Recorder

Post by apenwith » Fri 03 Jul 2009 11:13 am

Hi
I've been trying to post a reply for some time but my Tooway satellite broadband keeps breaking down. Hope the partial uploads haven't been a problem.
I found that when the sun intensity is low (dawn dusk) the timer got a bit unreliable so I have added a second LDR to try to bias the switching voltage. I've attached a simplified circuit diagram and an explanation in the hope that one of you electronics wizards out there can suggest improvements. Gratefully accepted!
Meanwhile with intermittant sun today test continue
Regards
Alan
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hans
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Re: Sunshine Recorder

Post by hans » Fri 03 Jul 2009 10:27 pm

you need a hysteris
to prevent oscilating when dusk/dawn (on/off/on/off).

you shouldn't need a second ldr,but a more direct "yes/no" for your opamp.

you could also try this
Image
the 4093 is a 4 NOR gate ic
if the input is high,then the output is high(see here: http://www.laynetworks.com/Basic%20Gate ... ctions.htm

but since you use an opamp(741?),try to find with google "opamp,hysteris"

apenwith
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Re: Sunshine Recorder

Post by apenwith » Sat 04 Jul 2009 9:15 am

Thanks Hans
Looking at your circuit it would seem there is always some voltage applied to the Nor gate -
at what point does the gate see that voltage as a high. (In my ignorance I thought that the
inputs had to be either on or off.)
As the circuit is already there I thought I'd try the opamp hysteresis way to start with - I guess
I'd have to remove the 330K resistor and the capacitor (which were supposed the reduce
cycling) and the LDR2 bit and put in the feedback resistor. Have you any idea what sort of
value I'd need. The opamp is an LM324 and the threshold voltage is around 0.606 v. The output when high is 11.35 V.
Actually the problem might be physical in that as the axis of the recorder head is the mean
virtual axis of the sun's rotation and when the sun is at it's most northerly (summer) rotation
the LDR only 'sees' the reflected spot from close to the edge of the sphere. In midday sun that
is stil bright enough but at dawn/sunset not quite so. The answer might be two LDR tubes in an
inverted Y configuration to 'see round the corner' of the sphere rather more. Then the question is whether to link the LDR's in parallel or to run two detector circuits so the either would switch
the timer.
Thanks Again
Alan

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hans
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Re: Sunshine Recorder

Post by hans » Sat 04 Jul 2009 10:46 am

your idea of making a hysteris with the 330k and capacitor is in the right direction.
only thing is;it connected wrong.

loose the capacitor and only use a(pot)resistor.(play around which value)
connect it to the Vin(pin3) of the lm324(where you already had the 330 connected),and the other side to the output of the lm324(pin1).

here is an example
Image

keep the diode(protection)
putting the 2 ldr paralel might work.

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Re: Sunshine Recorder

Post by Super-T » Sat 04 Jul 2009 11:02 am

Hans
Your Schmitt trigger works for me. I have been using your same circuit, except a 4584 Hex, as a daylight detector for my house lighting. As I've said before, the LDR tends to drift over time but not a problem to replace. Maybe it's just the extra bright sunshine we get down in NZ.
Alan
Schmiit triggers switch at 1/3 and 2/3rds the Vcc. Easier to use in this case than the OpAmp and you get lots of spare gates in the package. :-)

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hans
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Re: Sunshine Recorder

Post by hans » Sat 04 Jul 2009 2:27 pm

in case of the 4093,you could make the circuit 4 times(i think the 4584 has even 6 gates.),enough to "view" from horizon to horizon.but that is solved by using the lightbulb,maybe experiment with bigger/smaller bulbs.

an ldr is likely to worsen under bright sunlight,especially when it's working on it's limits,but is more sensitive to visible light than a eg.photodiode.
give it a pair of sunglasses :P and adjust the sensitivity.

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