Suggestion for simple RF switch module?

(James Reed) #1


I’m mixing and matching a few different systems and technologies, and I want to find a cheap way of steathily controlling them from the existing wall switches. I have already done this in places with Fibaro and other in wall devices.

However I now want to be able to just send commands from the wall switch. So what I need is a small battery powered module which I can hide behind the light switch which will send out some RF signals which I can interpret on the server side.

Does anyone have any ideas? I know that I could probably butcher one of those keyfob style remotes but that seems very messy, and also I would prefer not to use momentary switches if I can avoid it as these are relatively expensive compared with bog standard 1 or 2 way latching switches.

Any ideas?


(Crispin) #2

Not entirely sure what you’re trying to do. Did you want confirmation that a wall switch is on? Or, are you looking for a switch today have on the wallpaper which does something else’s in OH?
The latter could be a amazon button?

(Markus Storm) #3

I got some some relatively cheap devices to include (momentary) switches.
If you have Fibaros or Qubinos in cable range, some have a spare input that you might connect into.
An Amazon button is a good idea. You could also get a cheap ESP8266 such as a Sonoff.
Just be aware of the security risks when choosing WiFi or even cloud based stuff.

(James Reed) #4


Sorry, just to be clear what I want is a switch on the wall which I can use to do something else. So an Amazon button might well do for that, hadn’t thought of that before.

However ideally would like to keep it local if possible.


(James Reed) #5


Did you mean something like this?

I really want something ‘stealthy’ that I can hide in the wall with a normal MK switch on the front of it.

There is a Homematic device which does this sort of thing:

But it is expensive and I’m not sure of the compatibility. There seems to be a gap in the market for small cheap battery powered switch modules that you can hide in the wall. Could you hack an ESP8266 to do this? Would need to run off the mains as I think might be thirsty for batteries.


(CM6.5 H102) #6

Take a look at the shelly switches. I’ve read they are very compact so it should fit behind your existing switch.

(James Reed) #7

Great tip - thanks!

Never heard of these and they look really interesting.


(Markus Storm) #8

A Sonoff IS an ESP8266 that you can flash with custom firmware.
Yes or use Shellys or Fibaros, in ascending order of price and security and decreasing in size.

(Crispin) #9

Lightwaverf make a battery powered switch which looks like a normal switch but will do the trick. Very slim so will be OK to just stick it on the wall.

(James Reed) #10

Yes I’ve seen these sorts of things, but I’ve always found that the quality of the units is pretty poor with flimsy plastic and poor quality action. What I really want is a small module which is exactly the same but without the switches but with some terminals so that I can connect real lightswitches instead. Also ideally support for latching rather than momentary switches.

The Fibaro dimmers do this very well but are very expensive if all you want is to transmit some codes.

As per the above comments I’ve now ordered a Shelly1. The basic idea at the moment is to reflash it with ESPEasy and then use the GPIO pins to connect up some switches and read the status of these. They are cheap enough (12.99 delivered to the UK) to be worth a try for this. Unfortunatley as they are 3 wire I won’t be able to use them for much else in my house which has very little neutral to the wall box.


(Peter) #11

Wondering how you’ve got on with this? I have the same problem - I need battery powered devices to fit in place of or behind existing wall switches that have no neutral available.

Not finding anything suitable on the market I’ve built my own using cheap radio transceivers and a cheap low power microcontroller. It’s small enough to just fit into a switch box. I run openhab on a raspberry pi so I’ve connected a transceiver to its spi port and written some code on the pi that receives radio packets from the switch and publishes to mqtt. With an appropriate rule the remote switch then turns a room light on or off which has a shelly 1 hidden in the ceiling rose. Works ok, but the range is limited and I’m not sure yet about the battery life (a 3V button battery) since it’s only been up and running for a couple of weeks so far. Still working on both of those…

Another alternative I’ve thought about but not yet tried is to use a Philips Hue dimmer switch. I already have a Hue hub and you can catch the switch presses in openhab. The switches look quite nice, and you can get a thing to clip the dimmer switch on top of the existing light switch so you don’t even need to rewire anything. The device has extra switches for dimming, which would be redundant in my setup. Also I’m not sure what the response time will be like since the Hue hub is polled by openhab.