I have an RJ11 connector on my PCB. I'm considering using a telephone cord, but I'm worried about interference. I will have 8 cables in one bundle and I'm afraid they won't interfere with each other. I want to use it on DS18B20 (maximum 6 meters) and for I2C maximum 3 meters outdoors. Everything for the weather station.
I would also like to use a CAT5 LAN cable, but even if I use only 4 cores, it plugs quite badly into the RJ11 connector. I am therefore considering the simplicity of using a cable cable, which should go into RJ11 better.
I'm not clear from your description what you are doing.
I think you mean you are afraid they will interfere with each other.
Do you mean 8 cables or 8 wires? RJ11 is 6P, so up to 6 wires.
You can't put a cat 5 cable into an RJ11 connector, RJ11 is 6P, a cat 5 cable is 8P so won't fit, or did you mean use cat 5 cable with an RJ11 plug and the other wires loose?
You can't just pick wires at random, they are in twisted pairs and you have to respect that. I suggest 1 wire of the pair for signal, the other grounded.
I2C is not designed for more than a short distance, however it can be made to work over much longer distances than 3m, I have it working over about 30m without any problems. Set the clock speed low, use low value pull up resistors (maybe 1k) and use twisted pairs. Over 3m I would expect it to work OK over flat telephone cable, but I've not tried.
I mean 8 cables. The telephone cable is not shielded and if I use 8 cables, they will not interfere with each other.
I use RJ11 with 4 wires (4P4C).
My point is that I would use an STP cable and use only 4 wires from it, which I would connect to the RJ11 connector. The only problem is that it's pretty hard. That phone cord is ideal, but I'm afraid it can handle it.
That does not make sense. How can you say 8 cables won't interfere with each other? If they are bound together they will interfere, the question is whether the interference is enough to cause a problem.
I don't know what to suggest other than try it. I can't tell you it will or it won't work, but I can tell you that I think electronics is a great hobby for experimenting and trying things, to try it and see what happens.
I get the impression English is not your native language, am I correct? There are forum sections in other languages.
Are you aware that you can buy 4 core CAT5 cable STP? - that might be much easier to fit into your RJ11 plugs whilst still giving the advantage of being twisted pair compared to the flat telephone cable.