Hi,
take a look at the following two images that show how you would wire up a sonoff basic to control a lamp and a standard relay (controlled by some mcu) to do the same thing:
A sonoff basic actually provides 220V (or 110V) on its output, whereas a simple relay is just a switch. So if you intend to use a sonoff to replace/override some other kind of switch (physical, thermostat, whatever), you can’t.
Think you’re confused, the Sonoff only switches the live, same as your other example. There’s no need to connect anything to the neutral output on the Sonoff, think it even shows that in the instruction leaflet, they’re just made like that as the Basic was designed to be spliced into a cable.
It obviously needs both on the input side because that’s where the Sonoff itself gets it power.
Hi,
Indeed it only switches the live, but this is irrelevant. My point is valid. The Sonoff does not expose a normally-open and common terminals, so it cannot be used to blindly replace a manual switch. You need to make sure you’re wiring everything properly and understand what is connected where.
Thanks Lexam , I will take that into consideration when i receive the units. I will for sure ask again and confirm the connection , and spend sometime to understand more before testing this live… But I should be able to use it in conjuction with a manual switch , is that right.
I think that to avoid any further confusion, it would be better to see some wiring diagram before taking this any further. So if you can quickly draw something, we can all give more feedback.
Gotcha, because your example uses a mains power device there would be no real difference but you meant in general terms.
If you need to use the sonoff basic you can modify it a little and then use it as a dry contact relay.
Basically you cut the traces from the 110v side going to the relay and the common to the output terminal Then solder a jumper wire between the two traces going to the input side of the relay. Then connect the two wires for the circuit you want to control to the output terminals. Connect 110 to the input terminals.
Then when you turn on the relay it shorts the output terminals together.
I had a link to instructions to do it. I’ll see of I can find it again and post it. Its pretty straight forward once you see some pictures
Yes please It will be great to share the link so incan know from where to start for the connection and operation .
I think you mean this:
that will do it but the one i was thinking of was:
http://www.boized.com/2017/02/how-to-convert-wifi-sonoff-into-dry.html
Like it, even more ways to use a Sonoff beyond the obvious. Will use one like this to switch the low voltage line to my aquarium lighting rather than the mains voltage to the power brick.
In fact, I guess I could power the Sonoff using the 12v supply too using a 12 to 5v regulator, just need to work out where to feed the 5v in.
The right product for your use case is the Sonoff SV, but it seems a bit more pricey and comes without a box.
However I think for safety and for standby consumption is better to power off the power adapter while it is not in use.
I did look at the SV but two things against it, one, the case as you say, and in this instance I’d want to use it, and two, I already have a spare Basic in the cupboard 
Regarding turning off the power supply, it’ll still feed the pump which runs 24/7 as well as the lights, and the Sonoff now, and the original plan was to use two power supplies to separate the lights and pump. Otherwise I would totally agree and appreciate the thoughts regardless.
Thanks for the info everyone, I was thinking it would be more straight forward than it is as I remember seeing a photo of this setup a while ago
I’ve just spent a long time trawling through the forum to find the post again so I could see if I could work out how it was set up but it looks like I remembered what I saw incorrectly and the poster is switching the mains, which I obviously don’t want (I need the hot water to still work when the heating is off).
Nope, not switching the mains here. I have a switch connected instead of old Vailant thermostat. I just “stole” neutral line from the mains.
Hmm, then I may have to pick your brain when I get chance to open the boiler up if you don’t mind? I’m still a little confused about how to set this up, things may be clearer once I get the sonoff flashed and have a look at how the current thermostat is wired.
No problem, I’m glad to help if I can.
