Cumulus Support

I am looking for the reference of temp/hygr sensor for WH10180 (I guess that will be the same for W8681)

I found this one,

https://www.aliexpress.com/item/1005005 ... 07502746_5

DHT11 is compatible with WH1080?

Thanks

That does look similar but the original is only 2 legged. Can you take the number from under the one in your console?

Hi,

Sorry, I'm not aware that anybody has definitively identified a specific T/H device type for the "808x family" of stations, or even if they are consistent or compatible across the numerous versions which carried that generic model number for more than 10 years. They may have been designed and Manufactured by Hope Microelectronics, but AFAIK that manufacturer didn't sell components directly into the Open Market.

But have you looked through the two (rather long) "sticky" threads that appear at the top of this Fine Offset subsection?

Cheers, Alan.

Thanks Alan and Terry for both comments,

I can not remove the unit to see any serial number behind or so, only two legs of the device (DHT11 has three so I guess that it is not suitable)

To be honest, I am aware that it is not a professional weather station but I like to explore improvements, mods that could make it better (bearing in mind its limitations).

I have observed that my W8681 (like WH1080) has two issues related to temperature sensors

- Indoor: it keeps between 19.8-20ºC all the day (day and night) when at night it is close to 18.0C measured with other sensors. I can control the offset with the app but I'd rather to fix it (replacing it or whatsoever). I observed that the temp/hyg was touching main pcb board. I do not know whether, due to the functioning of the display it heats the pcb and keeps 20C inside so just added a piece of foam to separate it and isolate the heat. Let's see whether it does what is expected.
- Both indoor and outdoor sensors are two slow reading temp, you need 30' or more to see changes. I do not know (I do not have schematics or list of parts) whether there is anyway to speed up the measuring of the temperature.

Unfortunately I do not see a way to test other sensors as I do not have schematics to understand how does it work in case I replacement is placed (impedances, currents, etc)

I am using the W8681/WH1080 with the aim of getting values, exporting them with WeatherCat, processed with awk and send them via CW beacon via radio and, with Raspberry Pi, to show the values and graphs in a web page, so I would like to be sure that the information is valid.

Thanks!, Cheers, Juan

You mentioned that the Display might be heating the element.
You haven't converted the display backlight to be permanently on have you?

Hi Terry, no, I do not, indeed I do not know how to convert the display backlight to be permanently.

If it is not due to such heating, I only can think that the sensor is not working properly.

For instance, now it is measuring 19.6C when the real temp is 18C

Hi,

Some versions of those station Consoles automatically turn on the 4 "backlight" LEDs and/or have an internal mechanical relay (which clicks) when an external supply is applied (via the USB interface connector). In these cases an internal heating of about 2 degrees C is quite typical. IMHO, even now, relatively few temperature sensors achieve an ABSOLUTE accuracy of much better than 1 degree C and I've encountered >5% differences between measurements from even quite well-established RH sensors (such as from Sensirion and Bosch).

Strictly, all those "Fine Offset" versions of stations have been "obsolete" for many years now, and FO have morphed into "Ecowitt" who produce much more modern versions and are far more prepared to communicate with their customers. The majority of (T/H) sensors now use a (two wire) Data Bus structure, particularly I2C, my particular recommendation being those by Sensirion (e.g. SHT30/1/2 depending on desired accuracy and price). Those made by Bosch (e.g. BME.... series) are also a possibility, but only if you have access to good libraries for their 64-bit (typically) complex mathematical algorithms.

The operation of the ORIGINAL "WH108x" Temperature Sensor was analysed by Gina (RIP) on this forum in about 2010, and I may have posted some additional information. The external temperature sensor basically used a Ramp Generator formed from a Thermistor/NTC and 10 uF capacitor and timed/counted (16 bits) the ramp up to Vcc/2. Then a 16-bit lookup (table) converted to the temperature. However, these early stations used the SAME ADC to convert the Wind Vane (direction) into a digital value (again via a lookup) and any leakage current in the Vane connector or cable could play havoc with the measured Temperature Value (because both ramp generators shared the same timing capacitor).

Cheers, Alan.

Hi, Alan

Thanks a lot for the concise and "crystal clear" explanation. I will keep your comments as part of the documentation that I am collecting in order to learn how do these devices work.

Best