New Weather Station Build Pt.3

I have just added 'wind chill' to the mix and seems to be calculating correctly. I had to put in some static numbers for testing as wind chill is only valid when the wind is moving more than 3mph (4.83kph/1.34ms) and the temperature is below 10°C.

This is the formula: T_wc = 13.12 + 0.6215 * T_a * (0.3965 * T_a - 11.37) * v^0.16 Where: T_wc is the wind chill in Celsius temperature scale, T_a is the air temperature in degrees Celsius, v is the wind speed in kilometers per hour.

This is the output with static wind (10MPH) and temp (9°C):

Temperature: 9.00 | Humidity: 45.36 | Dew Point: 0.00 | Pressure: 1001.54
Wind Speed (ms): 4.47 | Wind Speed (mph): 10.00 | Wind Speed (kph): 16.09 | Wind Chill: 6.54
Wind Angle: 315 | Wind Gust (ms): 0.00 | Gust Angle: 0.00
Rain mm: 0.00 | Uptime: 30013

My head hurts now.... 😖 I have been banging away at getting all the fuzzy formulas in for calculating all the 'feels like' readings. I'm almost there but need to revisit a couple as I'm not happy with the results. So far I have programmed in the following:

• All the usual (wind/temp/humidity/pressure etc.)
• Absolute humidity (needs work)
• Dew Point
• Humidex
• Apparent Temperature
• Heat Index
• Water Vapour Pressure (needs work)
• Wind Chill

Once I get the two calculating properly I can move on to data collection. I also have to get the sensors back together and running. A good lick of paint is on the list too. Probably car primer grey as that is what the UK sky mostly looks like. Kinda fitting really. I have ordered some 3mm aluminium rod to rebuild the anemometer. I'm going for a different approach this time and having a long tail, and keeping it light to try and minimize the buffeting it used to suffer with. I don't think it will ever be right with where it is located, but it needs rebuilding, so I can have a try.

These are the readings I am now getting:

Temperature (°C): 28.20 | Temperature (°F): 82.76 | Relative Humidity (%): 44.04 | Absolute Humidity (%)*******: 27.31 | Dew Point (°C): 14.83 | Humidex: 32.07 | Apparent Temp (°C): 29.86 | Heat Index (°C): 28.15 | Water Vapour Pressure (hPa)*******: 22.38 | Pressure (hPa): 1004.78
Wind Speed (ms): 0.00 | Wind Speed (mph): 0.00 | Wind Speed (kph): 0.00 | Wind Chill (°C): 28.20
Wind Angle (°): 270 | Wind Gust (ms): 0.00 | Gust Angle (°): 0.00
Rain mm: 0.00 | Uptime: 2320013

I received the Marex weather station display. Its awesome. I love it forever! 😄 It looks and feels hand built. I had a stint on an assembly line back in the 90's making expensive fire alarm panels for some MOD contract. This looks, feels, smells and tastes just like the panels I was building back then. Massively over engineered and ridiculously expensive parts used. My Dad used to work for British Aerospace and would bring home all sorts of control panels and things from scrap for me to play with when I was a kid. This reminds me of the kind of stuff he used to get.

I really doubt there is any chance of me using it as is, or with light modification. It seems to have a single wire for data input and then the control board does whatever and sends data along a bus, where it is picked up by each module. Without knowing what kind of data was inputted it would be probably impossible to reverse engineer it to feed it the right data. having a look at the modules and the LED drivers, they seem complex. Much of which would be done in a single IC these days. I'm going to look into it more and see if I can get the LED segments working with the existing chips, but it's doubtful. I think I ma have to strip the PCBs right down to just the parts I want (LEDs) and drive them another way. I suspect a daughter board and a marathon of soldering is imminent!

The engineering in that unit is crazy, and expensive. It has a zillion-way connector for 4 wires.... Really, just 4 wires..... The PSU looks a good'n. Made by Volgen and even has Nichicon caps to boot! If it has Nichicons, everything else will be a good spec. The control board is boring. It has a CMOS UART and some glue logic. I think it also ahs some kind of power switch with a FET that turns the thing on and off when data is received or not. Plugging it in and turning on only shows an 'On' indicator and nothing else. It was also sold as 'does not power on'.

Alright, until the next update I'll leave you with this picture, and if you want to view the hi-res pictures you can download them here: https://www.blinkyslab.co.uk/download/marex_weather_station_display.zip

I have been toying around with the idea of using a real time clock and throwing an sd card into the mix. I could record all readings locally as well as on my web server. If the web server ever went down the ESP32 could make a note of the time and then when the server came back online it could upload (post, one by one) the records to the server. That way it shouldn't miss any readings unless the ESP32 went down for any reason. I could also use the sd card as a buffer of sorts for calculating things like rising or falling temps, or rising/falling pressure. It may also be necessary for the forecasting.

Until next time.

Archived from radmon.org - originally posted 02/05/2024