Analogue Weather Display

[Gina]

I thought I'd post a new thread to describe this part of my weather station as it tends to go with my other displays and I plan to have it next to my moon phase clock on the living room wall.  This will show current weather and trends whereas the weather data online covers the weather history of hours, days and months.

The plan is to have large analogue displays reminiscent of a clock face.  Wind direction needs to be able to point to all points of the compass and will have a clock type format with instantaneous and average direction.  A pair of stepper motors will provide the drive.  Wind speed will also have two pointers or "hands" and will be non-linear with lower speeds stretched out Beaufort style.  I'm thinking of a 300° display probably with geared up servo motors.

Most of the other weather data can also be displayed with 300° dials.  These will include temperature, humidity and atmospheric pressure, the latter also having a trend part to show if the pressure is increasing or decreasing.  Then there's rainfall, probably including rain in last hour, rain today and maybe rain over longer periods though I haven't thought this through yet.

When I get my sky condition and rain detector done I can add that data to the display.

[Davey-T]

Sounds like a plan Gina, I could build one but it would only need a picture of a big grey rain cloud 

Dave

[JamesF]

Sounds like a plan Gina, I could build one but it would only need a picture of a big grey rain cloud 

Dave

Oh, I don't know.  You could have measures of how hard it is raining, which direction the rain is coming from, which month it last stopped raining in and even how far up your wellies the mud will be if you step outside.  I'm sure the list must be endless...

James

[Tinker1947]

Its raining here, again

[Stub Mandrel]

Gina's living room, circa 2017:

[Gina]

Ha ha ha   Love it   Raining again here too.  Caught sight of a strange bright yellow object in the sky this morning between clouds - not seen anything like it for ages    I'm glad I added a bilge pump to my "ark" a while back - the ground is leaking again   It's deepest round the pier base!!!

Yes, rain in last minute might well be included to show rain rate.  My rain gauge is a tipping bucket type so needs a little while to collect data (and rain).  OTOH I could measure the time between tips for the rain-rate   I may measure time between revolutions of the anemometer to measure low values of wind speed too.  My weather station is based on an Arduino so most things are possible

[Garethr]

Gina,

At what point is it not easier to walk outside or look through the window.

I'm not sure i could get away with another astro gizmo in the house SWMBO is already concerned at the amount of time even on cloudy nights I spend in the Obsy just mucking about.  

Example tonight    

Gareth

[Gina]

Good point Gareth   I do venture outside sometimes (quite often actually) but I like to know the ferocity of the wind and how much longer I have "to build the ark"   So far the bilge pump has kept the water below floor level in the observatory - it's one hell of a pump

Oh and I am SWMBO   I don't always obey myself though

[Gina]

To get a 300° dial from a servo motor requires gearing up by 180:300 as the servos only turn 180°.   That's a gear ratio of 3:5.  Of course the simplest system would be to use 180° dials and just drive the pointers directly but for concentric dual or multiple pointers all but the inner shaft would need gears anyway so I guess we might as well use a bit of gearing up to provide a longer effective dial length in a given area.

[Gina]

I think I might add a float, lever and sensor under my observatory floor and provide a water level indicator indoors   I may also have observatory temperature and humidity.

[Horwig]

All this discussion of rain and observatories has just made me remember that I do have an observatory, but I've not been in it for so long I'm not sure where it is, and what it does.

Huw

[Gina]

I know what you mean Huw

[Gina]

I may have some gauges covering 180 degrees and placed side by side to save space.  Pointers can be driven directly by micro servo motors.

[Starlight 1]

It not be long before you have a rain sensor contoling a motor to tip you out of bed to shut the roof.

[Gina]

Oh I'm planning to do better than that - the roof motor and control system is almost finished and will cloce the roof at the first hint of rain.  I like your idea though

[Gina]

Looking at how many control lines I shall want from the Arduino prettry sure it needs a Mega but let's see :-

1. Wind direction current - stepper - 4 lines
2. Wind direction average - stepper - 4 lines
3. Wind speed current - servo - 1 line
4. Wind speed average - servo - 1 line
5. Temperature outside - servo - 1 line
6. Temperature inside - servo - 1 line
7. Relative Humidity - servo - 1 line
8. Barometric Pressure Current - servo - 1 line
9. Barometric Pressure Trend - servo - 1 line
10. Rainfall Rate - servo - 1 line
11. Rainfall Today - servo - 1 line

I make that 17 data lines - definitely a Mega (or two Nanos).

I haven't yet decided how I'm getting data from the sensor system to the display.  Two options - wired or wireless.  Wired would likely be serial over a twisted pair and wireless might be a radio link as I have a couple of radio comms modules.

I've been thinking some more about the gauges and thinking some might be linear rather than a dial.  I could use a painted timing belt or a rack and pinion.  Linear gauges would take up less room.

[Gina]

Another idea for linear gauges is string and drum with the string pulling up a slider.

[tekkydave]

Didn't you design a 1-wire driver for another project? You could use a Nano and some DS2408s to expand the number of lines.

[tekkydave]

I think it was your CCTV system.

[Gina]

Just checked my thread on that project and yes, you're right   I'd forgotten about that - the CCTV project has been shelved for some time now.  Certainly another option for the weather display   Could be more complicated though - I'll check it out.

[Gina]

Update :-

This project is currently shelved while I sort out others and hopefully finish one or two   I don't need weather dials to tell me what it's doing lately anyway - the wind howling round the chimney tops and rain hammering against the windows tells me all I want to know

Same applies to my main weather station project.

[Gina]

Now that my observatory sump water level control and display is constructed and the project is at the testing and running in stage, I am resuming the wall mounted weather dials project.  Indeed this also includes the water level dial as it's sensible to combine the displays.

With such a large number of dials I wonder if I'm sufficiently recovered from my previous struggles with the DS2408 as to be able to resume the struggles   Hmmmm...

I can however, look at the mechanical design of the dials and box.

[Gina]

The Arduino Nano that is driving the sump water level indicator is only using one analogue input and one digital output.  This means it has a lot of spare capacity so I think I'll make use of some of that.  Most of the dials can be driven by micro servo motors which require one digital output each.  I don't think these can be driven from a DS2408 so will need digital pins on Arduinos.  This pretty much dictates the use of either one Mega or two Nanos - I think I prefer the latter - cheaper too.  Even 3 Nanos would beat one Mega I think.

The next question is how many dials are wanted.  I was contemplating temperature and humidity readings for both scope room and warm room but I'm wondering now - do I really need all these dials or would a computer display be sufficient.  I like the idea of having outside temperature and humidity on a wall display but not really sure about scope and warm rooms as well.  More work and more clutter - is it needed?  Maybe not.

A new list of dials then :-

1. Water level in sump - 180° servo *
2. Wind direction - 360° - stepper motor
3. Wind gust speed - 300° - geared servo
4. Wind average speed - 300° - geared servo
5. Outside temperature - *
6. Outside humidity - *
7. Rainfall rate - *
8. Rainfall in last hour - *
9. Barometric pressure now - 300° - geared servo
10. Barometric pressure rising or falling rate - +- 90° servo

* may be linear with servo

That make a total of 9 servos and 4 lines for a stepper motor = 13 altogether so more than one Nano could handle unless the stepper is handled by 1-wire.  But the bits to do it by 1-wire would cost more than a Nano so not cost-effective aside from being more difficult.

[Gina]

Vertical linear dials take up less room than rotary dials and look better for some data.  But I think the sort of dial is more customary than practical in most cases.  Wind direction has to be rotary because the wind can come from any direction so the dial needs to rotate 360°.  Wind speed and atmospheric pressure are traditionally rotary with something like 300° rotation.  Temperature and humidity can be either though thermometers and hygrometers started by being linear.  Actually, so did barometers but I think we are more used to aneroid barometers than mercury.  Things like water level and rainfall would seem to fit well into the vertical linear type.

[Gina]

These are a couple of images of the dials I've used in the past on my weather web site which serve as suggestions but the hardware versions will be a bit different.