[Solved] Sonoff Touch Wi-Fi: Can One Replace a Stair Switch & Work with Old Switch Installation?

Good morning,

I plan to replace the light switches at home with Sonoff Touch Wi-Fi. I am mainly concerned about the stair switch. If I replace only one of the stair switches with Sonoff Touch, will the installation work properly? For example, will I be able to turn off the light with the old switch and then turn it back on from the other side of the corridor with the Sonoff switch?

I found a movie in which the author shows how to connect two Sonoff switches together so that they work like stair switches: (I can't enter the URL in the post because I am green, but to find a movie, enter the phrase "Sonoff switch M Federico" in the YouTube search engine). The question is, if I replace only one of the existing switches, the system will behave the same. It may be a trivial problem, but as a complete layman I can't even imagine it after research

Thank you in advance for your help.

From what I saw in the movie such a hybrid will not come out

I have a similar problem, but I'm still trying to solve it somehow. Well, the case is as follows:
I have sonoff touch installed in two different places. The 3-wire cables go to the switchboard (from both). Wires from the bulb (lighting the living room) also 3-wire go to the switchboard. And now my case is breaking down how to connect them (read what to use) to make them work alternately. I was thinking about a NO + NC bistable relay, a NO-NC contactor or something else (my ideas are exhausted) on a DIN rail, but sonoff touch is not a bell switch and if I apply voltage to one, then if I don't look, the voltage will be on the contacts all the time. Do you have any ideas? Can use a combination of several relays with contactors - I have a lot of space in the switchboard

Added after 21 [minutes]:

All in all, I found how to solve it.

Page 13-14
https://drive.google.com/file/d/1fTCDkL0eNJmj2Xdq4lZDCEFCT7Y5J5-L/view

https://www.easy-do-it-yourself-home-improvements.com/3-way-switch-wiring-diagram.html

https://www.youtube.com/watch?v=iyZwcZS7Qu4

https://www.youtube.com/watch?v=EroQ_Eos1HY

I think it can do without additional contactors, relays, etc.

which variant did you use and what sonoff devices did you use?

Added after 3 [hours] 57 [minutes]:

mcincin wrote:

I have a similar problem, but I'm still trying to solve it somehow. Well, the case is as follows:
I have sonoff touch installed in two different places. The 3-wire cables go to the switchboard (from both). Wires from the bulb (lighting the living room) also 3-wire go to the switchboard. And now my case is breaking down how to connect them (read what to use) to make them work alternately. I was thinking about a NO + NC bistable relay, a NO-NC contactor or something else (my ideas are exhausted) on a DIN rail, but sonoff touch is not a bell switch and if I apply voltage to one, then if I don't look, the voltage will be on the contacts all the time. Do you have any ideas? Can use a combination of several relays with contactors - I have a lot of space in the switchboard

Added after 21 [minutes]:

All in all, I found how to solve it.

Page 13-14
https://drive.google.com/file/d/1fTCDkL0eNJmj2Xdq4lZDCEFCT7Y5J5-L/view

https://www.easy-do-it-yourself-home-improvements.com/3-way-switch-wiring-diagram.html

https://www.youtube.com/watch?v=iyZwcZS7Qu4

https://www.youtube.com/watch?v=EroQ_Eos1HY

I think it can do without additional contactors, relays, etc.

If the right switch is in OFF mode at the L out output, then how to turn on the bulb with the left switch if there is no phase on the left Lin?

Hello,

this is done through the Ewelink application.

I don't know if something has changed in the sonoffs themselves, but I gave up this solution for the benefit of Shelly drivers. Works well in a system with stair switches.

On two TH1 sonoffs you can easily turn on the stair switch. You can use one switch in the circuit with the bulb and the other as controlling the scenario. The advantages are that there are no problems with replacing the batteries in the remote controls and the sonoff TH1 is much more precise compared to the surface-mounted remote control.

https://youtu.be/TQ9BjEwTDa4

It seems to me that the original question was whether it is possible to connect an ordinary sonoff stair switch in one circuit. The answers so far indicate that no. This can only be done with two sonoffs in the master-slave formula. But ....
I have an untested idea that I think will work:

We buy a two-button sonoff, which means that it allows you to connect L_in with L1 and L_in independently with L2. Of course, I assume that you have a new type of installation and you have access to N to power your Sonoff.
The stair switch works in such a way that by connecting one pair of wires, it disconnects the other. With a two-button sonoff at our disposal, exactly this behavior can be simulated in theory. Using Ewelink, we configure that turning on one button turns off the other and vice versa. The idea seems quite simple, and should work even in a multi-button configuration with cross connectors.

Of course, having two adjacent buttons to perform one and the same action is not ideal, but at least from the cost point of view of a two-button sonoff, it costs much less than two one-button sonoffs.
The disadvantage of this solution is one more - the home automation system will not know in which position the light is on and in which it is off.

However, if we are looking for the most economical solution, sonoff mini will do the trick and costs PLN 30. But I failed at home trying to stuff it into tight cans. Besides, I've come to the conclusion that I don't like my old buttons .