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Solar and UV sensors going off line - fix?

Discussion specific to Fine Offset and similar rebadged weather stations
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steve
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Re: Solar and UV sensors going off line - fix?

Post by steve »

mcrossley wrote:Well they do, but only if you start the clock for both of them at the same time.
Ah - I didn't realise that was an option.
Steve
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Re: Solar and UV sensors going off line - fix?

Post by oman181 »

Thanks Alan,

It's an intriguing problem and one I would like to figure out. Even though my technician days ended about 15 yrs ago, there are some brain cells that remember some stuff and I do like a challenge!

Any idea what interface the 6 wire is - RS422 / 232 or other?
Maybe 2 of the wires are +ve supply and a ground. Leaves enough to do either of RS232 or RS422 with one control line from the transmitter possibly signalling to the solar panel that the transmitter is busy so hold off sending your packets. Or is that too simplistic... or clever? Might be time for a break out cable when I have some of that rare commodity = time.

.... and the ebay seller I got mine from has just sent me a new solar panel to try out. But my hernia recovery prohibits me from hauling out a ladder and getting on the roof. Another couple of weeks.

Cheers, Phil
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Re: Solar and UV sensors going off line - fix?

Post by AllyCat »

oman181 wrote:Any idea what interface the 6 wire is - RS422 / 232 or other?
Hi Phil,

I think you can assume "other" or "proprietary". The data appears to be the raw modulation signal to be applied directly to the RF transmitter module, wth a format quite different to the other FO "108x" family of stations.

The cable connections are indicated (rather offset) on the PCB legend in the 6th post on this page of the "photos of...." sticky thread. The RF-Data is at one end of the 6-pin connector and "No Connection" at the other end, with VDD, GND and RAIN, etc. in between.

Cheers, Alan.
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Re: Solar and UV sensors going off line - fix?

Post by ejay »

On the pin that is designated 'RF', it could be either of:

1) a modulating signal that is fed to the thermo/hygro transmitter's input (in parallel with the temp/hum/wind/rain signal), which gets modulated there to be transmitted in some proprietary ASK/FSK format.

2) a 433/866 MHz pre-modulated signal (again proprietary), fed into the thermo/hygro's RF output drive circuit (essentially to share the antenna).

I'd think that the first option is more likely, seeing that the solar pod circuit board seems to have omitted the transmitter (and battery) components, so it's piggybacking off the thermo/hygro transmitter.
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Re: Solar and UV sensors going off line - fix?

Post by MartinHJ »

AllyCat wrote:
JohnF wrote: ATM the UV is reading 11 and Lux 46 with the piece of tape over the sensor and the data is still solid.
Hi,

As Summer approaches here in the UK, we're probably now seeing the "Australian failure mode" ("crashing" of the solar module software due to high light levels) rather than the "UK failure mode" (excessive power drain by some solar pods causing flat batteries).

Note that there are three "Solar Sensors": The sloping PV panel might be charging the batteries to too high a voltage (but the circuit appears to include a voltage regulator to prevent this), or a computational "overflow" of the UV calculation might easily occur, because most/all of the units clearly over-read very considerably (the highest UV value in the UK should be about 7 or at most 8). However, John's comment above (and I think some from Australian members) suggests that it is the Lux value (from the "domed" sensor) which is causing the problems. Rather strange; have you ever seen Lux values approaching the 400k which is supposed to be the upper limit of measurement?

Cheers, Alan.
I have just received a replacement solar unit as mine was locking up/kept going offline. Will see how it goes...one encouraging bit of info is that today on a hot sunny day here in the UK the UV reading is 8. The old unit would have been reading double figures! Clearly they have made some changes

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Re: Solar and UV sensors going off line - fix?

Post by MartinHJ »

MartinHJ wrote:
I have just received a replacement solar unit as mine was locking up/kept going offline. Will see how it goes...one encouraging bit of info is that today on a hot sunny day here in the UK the UV reading is 8. The old unit would have been reading double figures! Clearly they have made some changes

Martin
Alas they are changes for the worse in some respects. Whilst the solar unit does not lock up completely it now produces very bizarre UV readings! See attached file. The first days graph is of higher magnitude due to me applying some scaling factors in Cumulus before I realised that was a lost cause!

Martin
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Re: Solar and UV sensors going off line - fix?

Post by steve »

It looks like it registers every value above about 8.5 as 4.0 (apart from where it goes even stranger). Is the console showing the same value? (just to make sure there's nothing odd going on in Cumulus)
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Re: Solar and UV sensors going off line - fix?

Post by AllyCat »

Hi Martin,

Are you sure there isn't still a calibration factor set up in Cumulus?

AFAIK the FO station only reports integer UV values, but your graph appears to have about 16 levels up to the "8.5" level. Also, what Lux values is the station reporting?

Cheers, Alan.
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Re: Solar and UV sensors going off line - fix?

Post by phin1 »

Has any body got an indication on how accurate they think there UV is. Mine is reading 11 on a winters day, Local weather station says nothing above 2
And how would it be suggested to attenuate the readings. I have reasonable electronics knowledge.
Another question is what is the raw data cumulus receive, and what does it calculate as far as solar is concerned
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Re: Solar and UV sensors going off line - fix?

Post by steve »

phin1 wrote:Another question is what is the raw data cumulus receive, and what does it calculate as far as solar is concerned
It gets the UV value, and the Lux value. It attempts to calculate a solar radiance value by multiplying the Lux value by 0.0079; this factor can be configured by adding a LuxToWM2 setting to the [Solar] section in cumulus.ini. From the solar radiance value it attempts to determine whether the sun is shining or not at any given time, using a formula whose parameters can be configured via the station settings screen.
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Re: Solar and UV sensors going off line - fix?

Post by AllyCat »

Hi,

As I've said in a number of other threads (including one yesterday), IMHO the FO sensor does not measure the narrow band (UVB) which is required for the "UV Index", so calibration is impossible ("garbage in = garbage out"). If you want the measurement to look more plausible then you can use a calibration multiplier of perhaps 0.3 - 0.5 within Cumulus. But proper calibration needs (at least) a sharp-cut UVA/visible filter (pass only UVB) over the sensor and access to a reference standard. That's probably one reason why the Davis UV sensor alone costs around $1000.

My justification for the above statement is that my FO "UV" sensor has given high readings, for example behind laminated glass (which is generally accepted not to pass UVB) and even from an incandescent lamp (hot wire not the low energy type) which should not radiate any UV.

Cheers, Alan.
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Re: Solar and UV sensors going off line - fix?

Post by JohnF »

Like many others, my W-8681-Solar was displaying --- where the Light level and Lux readings should be.
I replaced the 2 Alkaline batteries with NI-MH types in the transmitter, put a little bit of tape over the solar panel and that did the trick.
Well, at least I've not had dashes for about 3 weeks now.
Thanks for all the great info in this thread.
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Re: Solar and UV sensors going off line - fix?

Post by basetman »

I just wanted to share my experience with the Watson W-8681-Solar weather station, which is a rebranded FO WH3081.
I have been using this station since April and apart from the solar and UV sensors going offline I have not experienced any other serious problem.
The solar and UV sensor were working fine fow about a week, then the console started losing the signal from these sensors and displayed "---". I resetted the transmitter and the receiver several time but thw sensors would work for acouple of hours and then they go offline again...
I tried to ground the oscillator crystal, as it was suggested in the first post of this thread.
Nothing changed. Then I replaced the rechargable alkaline batteries that came with the station with NiMH batteries, but again with no success.
Before about a week I tried another suggested solution. I added a 3300μF capacitor at the point Zed_Man suggested earlier in this thread.

https://cumulus.hosiene.co.uk/viewtopic.p ... &start=100

It seems to have done the job!!! The sensors have been working continuously for 6 days! I keep my fingers crossed, but the problem seems to have been solved! The accuracy of the light sensor is not that great (they are about 20% off), but for a 120€ weather station that is to be expected... The UV sensor was way off the official UV values for my region (12 instead of 6), but I applied some tape over the sensor and at least the maximum values agree!

Great program by the way, Steve! Keep up the good work!
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Re: Solar and UV sensors going off line - fix?

Post by Cookie »

Hi, I'm new to all this and I see others have experienced problems with their solar and vu sensors. I'm having the same problems, does the the capacitor modification described earlier fit the problem? There seems to have been alot of effort put in to find the issue but I'm not sure what the final outcome is. Your help would be appreciated.
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Re: Solar and UV sensors going off line - fix?

Post by AllyCat »

Hi,

Unfortunately the Solar Pods of these stations can suffer from more than one type of fault, sometimes with similar symptoms. If the TX (Low Battery) icon is displayed on the Console then the Pod electronics may be draining too much power, for which the only (known) solution is replacement of the Pod. If the Console displays "--" for Solar values, but the values can be restored by holding in the <down-arrow> button on the Console for around ten seconds then either the "capacitor" or the "soldering the crystal" modifications MIGHT work.

However, the most common issue appears to be the Pod software "crashing" due to an excessively high light level. AFAIK this requires the pressing of the Reset button on the underside of the Pod (or maybe disconnecting the transmitter batteries when it is dark) to restore operation. Prevention appears to be possible by adding a light filter, probably over the UV sensor (which is just to the left of the sloping PV panel); but maybe the Lux sensor (dome on the right) or the PV panel (overcharging the battery) are responsible.

Cheers, Alan.
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