Hi. I did a terrible mistake and used 3x1.5mm coper wire that are usually used in power lines to extend the sensor over 15 meters. It's already in cement is there any way to make it work with resistors? How to select the right resistor? I also have a few free 1mm cooper wires used with termostats in same location. I hoped that more coper - better. But looks like no.
Not nearly enough detail - you would have done better to start a new thread and explained your setup in detail.
PVC covered mains cable buried in cement will be absorbing moisture content, and thus be significantly lossy at high frequencies, but this might not matter too much for a DS18B20 which is not running at high MHz rates.
What pullup resistor have you tried? Do you have a decoupling cap at the sensor itself?
Thanks for the reply. I have multiple sensors. Sensor on 10m native cable works ok. 3 other with native 5m + 10m of mains extention cable didn't work. I was testing it with digital temperature relay with 2 inputs one for data other for ground and power. Relay shows error reading sensor messege. Hope that I will make it work with arduino on the later stage. I want to use sensors as extra layer of security for protecting wooden floor over concrete with radiant heating. It has 26° temperature limit and it's hard to guess exact water temperature at the begining. So if concrete temperature goes too high arduino will close the valve/shut the pump. Looks like it's almost impossible to extend DS18B20 with ready made devices. Sonoff has 5m extention cables that can be connected in series but if you try to cut the wire and just connect a sensor with longer cable it will not work..
How many conductors does this "mains extension cable" have?
This topic has been merged into Re: extending cable of DS18B20.