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Wednesday, 26 February 2020 00:21

Videos of the weather in Hassocks. These videos are uploaded every 10 minutes. The view is approximately due south, the south downs can be seen in the background.

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Hassocks Weather Station

 

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SouthDowns small

View over the South Downs from the weather cam

approximately south facing

Over the last few years, when snow has fallen the rain gauge stopped working. It then took a number of days before operation was resumed. When the gauge started working again, the water would be measured at the wrong point in time indicating it's raining(snowing) when it's not.

Following are images without any heaters fitted

DSCF8143 DSCF8144

A number of people have come up with a number of solutions, including putting a 12v bulb in the rain gauge to heat it, resistive cable that heats, and resistors. Most of the solutions I have reviewed seem to have a major drawback, a lack of accurate control of the temperature of the rain gauge. So after some thought, I have come up with this solution, maybe a tad over the top, but a bit of fun, well for a techie anyhow.

The following images are of the guage with the resistor boards fitted.

DSCF8153   DSCF8157

As I have started playing around with the Raspberry Pis since they have come out, this seemed an ideal opportunity to put it to the test. To act as the heater controller. The Pi I used is already working as a NTP Stratum 1 server and also running a few other minor projects, so a good bit of reuse.

The following images show the Raspberry Pi and the connectors, the HTR is the connection to the Heater Control box

DSCF8076  DSCF8077 

So the design... It had to be temperature controlled with respect to the rain gauge. My main concern was heating the gauge up too much and melting it, but enough to melt the snow/ice.

I also wanted to use Cat5 cable, it's cheap and plentiful. The next Issue was, how much wattage would be needed to heat the gauge, well a bit of a finger in the air on this one. I know 12v bulbs seem to work to a degree, so as I know one bulb is not always good enough, thus multiple heaters was going to be needed. This then brought me into thinking how many, back to the Cat5.. I need a pair of conductors for the temperature monitoring (1 Wire bus), leaving me with 3 pairs. Next problem, current, Cat5 is limited to 0.5A per conductor. As there were 3 pairs left in the cable this would indicate 3 * 0.5A or 1.5Amps. Voltage is the next issue, as we need around 12/15 Watts per circuit/pair, 12v is not enough, as 0.5A * 12v = 6Watts * 3 heaters = 18Watts, not enough . After a search of Ebay, I found a couple of PSUs around 32 Volts and 2 Amps, ideal, and cheap :-)

3 sets of 4 * 15ohm 5Watt Ceramic Resistors were used to ‘deliver’ the heat. The three groups are spaced as equally as possible around the gauge.

We now have the cable and the PSU sorted, now for the control circuit. As the Raspberry Pi has such a simple input/output system, all that would be need is a simple set of relays to turn on/off the heaters. A separate control module would be needed to energise the relays and monitor for any fuse failure. The other issue is that as the relays are 12v. A 12v regulator would also be in the control enclosure, there would be heat generated from this as well as the LED current limiting resistors, and thus quite a bit of heat would be generated in the control unit. So as there is a temperature sensor in the rain gauge, why not put one in the control module, I Wire is very well suited to this as one can put them in parallel on the same pair of conductors.

IMG 8202  IMG 8187 

The unit does not need to be live all year, in fact only a few days a year. As I did not want the PSU using power all the time I plugged the PSU into a ZWave controlled mains switch, which can be controlled by the heater software and so the PSU can be switched on and off when needed. This also has an advantage that if there is a problem with the heater circuit failing and getting stuck on, the power can be removed automatically/remotely, thus allowing for the shutting down of the whole heater system.

The following page shows graphs of the rain gauge temperature, controller temperature and when the heaters have been turned on. rain gauge heater graphs

 

The top two graphs show the temperatures of the rain gauge heater and the control module

The lower two graphs show the heater status of the rain gauge. There are three independent heater circuits, which are turned on sequentially depending on temperature of the rain gauge.

The graphs are aligned with respect to time, so it can be seen when the heaters come on with respect to temperature.

gauge-temperatures-30Days  gauge-temperatures-24Hrs 
heaters-30Days heaters-24Hrs

At the beginning of this year (2013) I decided to carry out a full referb of the weather station. When I took the station down last year (2012) I found lots of issues with it, mainly to do with the inconnecting wires between the different sensors. I decided to improve the ease of connecting the sensors together. Be it that the sensors use RJ45 connectors, it seemed sensible to use water/weatherproof RJ45 connectors. I found a good supply at solwise. The only problem is that they are quite large with respect to the size of the sensor housings. So major rebuild of each housing was required.

The station also need a bit of a repaint, it was showing signs of deterioration. The last time the parts were painted was many years ago.

The left picture is the base of the Stevenson's screen, and the right is the base of the wet leaf sensor mount.

As the wet leaf sensor was a little unstable putting the mounting poll through the connection box seems the ideal solution. This was pretty tricky to achieve as the main mounting poll had to be in the centre of the base, the housing base and the housing lid.

Here you can see the wet leaf sensor housing quite clearly here showing the difficulties of modifying it. The holes in the housing are for the waterproof RJ45s

More of the leaf sensor housing

...

 

This is the housing for the UV sensor, again showing the waterproof RJ45s and also some lead to make sure it does not move around.

More lead

Here is the start of the construction of the splitter boxes. The idea of these boxes is to allow the 1wire bus to branch to the sensor and back, holding true to the way 1wire network needs to laid out/connected. The other advantage of this, is that the sensor can be isolated from the rest of the for problem determination.

The following pictures are the RJ45 splitter board that is fitted within the housing. This allows easy connection of the waterproof RJ45 sockets fitted in the housing. I used RJ45 couplers, the ones a got easily split and disassemble.

Little bit a paint..

These are the images of the wiring harness in the splitter box.

These pictures should give a good idea of how they are wired, the left shows the 1wire bus being split out and back to the third connector.

Here is the internals of the splitter box. As the RJ45s take a large amount of space, I fitted stand-offs which I then mounted the splitter board on. The socket on it's own is the connector for the sensor the box is being used for.

 

This shows the splitter board and then it mounted in the housing with the RJ45 waterproofs connected. You will see the top cable has a label on it, this is the one to the sensor, so when I have to take it apart I will not have to trace the cables around in the housing.

More construction pictures of the splitter boxes

The finished item

To protect the computer that is running the station I have fitted a lightning arrestor to the 1wire bus. This  sourced from solwise. I also have a lightning earthing rod in the ground, which it's connected to.

The bottom picture is the splitter box for the soil temperature sensor.

 

I brought the 1-Wire UV Sensor about a year ago from Hobby Boards, however there were issues with it working on the 1-Wire bus. After a little too and frowing with the supplier, the problem was rectified, their support was very good. So the sensor has only been connected for the last few months, not much Sun this time of year (March 2012), so it's only picking up very very low levels so far!

The only issue with this sensor is the fitting it to a waterproof housing. The housing supplied is not waterproof. The issue in rehousing this, is the window that the sensor needs to detect the UV, has to be of a special material, not easy to source in small amounts, so I had to use the supplied housing lid with the supplied 'window', but integrate it into my own waterproof housing. I did consider removing the 'Window' from the supplied case, but this looked like I would do more damage to the perspex that worth, so I cut an extract hole the size of the perspex window in the lid of the water proof case and epoxied the hole top part of the Hobby Boards case in, worked!

You will notice two lumps of metal in the box, these are lead, to stop it blowing off my flat roof.

UV-Open-Small

UV-Open-Top-Small UV-Closed-Small

The next image shows the sensor placed in a clear area of the flat roof, which gets the Sun nearly all day, so the readings should be quite accurate over the whole day being that the Sun is out, but then we do articlesin the UK :-)

uvsensor-onroof

Over the last year or so I have carried out very little maintenance on the station. Well it caught up with me in the last couple of weeks. The station completely failed. After finding some time when it was not raining or snowing, I have managed to carry out the repairs.

The first issue was with the solar sensor, which I had thought was producing very odd results. The sensor failed so badly that it took down the data-bus that sends the sensor data back to the PC. Luckily I had brought a spare sensor earlier in the year. I have improved the mounting of the sensors in the housing. Before I used screws with insulated washers, this time I have used nylon standoffs. This should allow the flow of air more easily around the sensor, stopping any dampness causing any issues. Both the solar/temperature and the humidity sensor have now had this modification.

 

The fan that is fitted to the housing, had also stopped working, this was a simple fix, one of the wires that are connected on the back of the fan had come adrift, (rotted though). I reconnected it and this time put plenty of silicon compound around it, this should stop any moisture getting to it.

I also tidied up the wiring as this has always been a bit of a mess.

Once these repairs were completed I carried out some testing, which looked fine. The only oddity was that the wind speed sensor was not picking up anything, however there was very very little wind that day. About two days later I noticed that the wind speed sensor was still not reporting any wind, however now it was very windy! I had noticed that the cable that goes to the wind instrument was looking very unwell. It was cracked! I brought this cable as a UV protected cable, well it certainly was not, in fact I have normal patch cables being used, and they are fine, considering some of them have been in place for 5 years, where as the special UV protected cable had only been up for 2 years.

I have installed a Dallas 1-Wire Weather station on my house. My house is located in a villiage called Copthorne, in the South East of England. Click here for upto date weather. The location of the unit is not ideal, however it means I do not need to get a ladder out to look after it... and I'm not that keen on heights

WeatherStation1

 

The following image is quite old, the wind sensor is now at the top of a 3 meter poll! But it gives an idea of the setup.


My weather station, in all it's glory, well plus a few house bricks to stop it flying away. I have now mounted, screwed down the the rain gauge to a small paving slab. We had some strong winds a while back and I found the rain gauge swinging from it's data cable :-). The main problem with sitting this station is that I can not screw it down to the roof, thus bricks have to do. This is probably not the best site for the station but it has to do. I regularly check its results with a local 'real' weather station, and it comes out very well, considering it's a hobby.

Station2006

MainBoxOpenCloseUp MainBox

Above is the Stevenson 'box/screen'. It contains the Humidity sensor, temperature sensor, lightning sensor and solar sensor.

The solar sensor it's self (the light sensitive part) is mounted on the very top of the 'box', you might be able to pick out the green/yellow wire in the pictures above.

The lightning sensor is also where I have connected the temperature sensor to. However I will need to move the lightning sensor further away from the house as it seems to pick up every time someone turns on a light in the house.

Station In The Snow 2007

House Power Usage

Latest Sensor Changes

House Temperatures

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Sun Up, Sun Down

06:5512:1217:31 
Hassocks, West Sussex

Moon Phase

Moon phase
Phase:
Waxing

Illuminated:
5%

Age:
2 days

Distance:
251,965 Miles

Time:
00:21:29 GMT

Date:
02-26-2020

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