@MikeF Dirtypcbs rarely takes more than 3-4 weeks for me too (in germany), but you are right, a local source would be great. There are several producers here too, but for everyone I know prices are at least 5 times what the chinese take.
If you (or someone else) finds a european service that produces prototypes (1-3 boards) for less than 15€ per piece please share it! Could come in very handy when developing new boards.
@rvendrame transformers often contain two 115V windings (but not the ones that I bought), so you can connect one of them to use in 110V environment or connect both windings in series to use in 220V environment.
As for time and assembly size - yes, you are right, but for low power devices it's possible to use very small rectifier bridges (or just two sot-23 two-diode assemblies), and small sot-23 LDO (for examle, very popular XC6206P332MR - 662K). So all them with capacitor(s) will be almost the same size on PCB as well-known Hi-Link switching power supply.
No problem, I am running the nrf24 mqtt gateway on the rpi and it is working with no problem with domoticz. I choose the mqtt client gateway because I wanted to tinker around MQTT, but you could go for the ethernet gateway that is easier to manage.
@Lee-Groom - over time the community have found out that its best to power the radio directly from the batteries and not through the booster due to what @AWI said. Thats how i build my PCB. The nrf24l01+ can handle down to 1.9V so you have atleast a span of 1.9 - 3.3v to work with if you are using 2xAA.
I would suggest powering your radio directle from battery and the rest throught the booster. Filter the booster with 0,1uF cheramic cap on the output (I dont know why, but learning by doing i have found this to work the best for me). Also be aware of that out of 10 china boosters i get atleast 2 that is so bad they generate so much noice its hard to get a good circiut.
Hi jfeger, sorry I can't find the sketches anymore... if I end-up finding it I post here.
So, I decided to use bare Arduino with the RadioHead RFM69 lib and parts of the Talk2 library. I just didn't feel the need for the whole framework and doing this I was able to customize a bit more the low-power usage and easily integrate with other third-party libraries which weren't playing nice together with MySensor.
In terms of messages, protocol I just follow the Talk2 example and I'm using their "Message" format. I just assigned the "id" to a kind of message by convention and use the 8 bytes payload for the data... I normally use only 1 to 4 bytes actually.
@mfalkvidd Thanks for the careful and understanding explanation. Of course it makes sense that salt water is more conductive than tap water and distilled water. I will calibrate and map according to the specific soil I will use the sensor with. Thanks
@Yveaux I haven't tried that, but that was a good idea to see if the sensor itself has any issues with the conductivity. One can never completely trust cheap chinese hardware..
It depends on what your final setup will be, because you could load a custom firmware that sends data to mqtt or write your own code and use it as an esp8266 gateway with sensor attached. There is no universal solution, so if you would like to post your project we can give better suggestions.