I practically don't use any smart relays in my smart home, it's clear that smart sockets are the same relays, and I have quite a lot of them, but I stopped using smart relays a long time ago for several reasons.

But in the beginning, when I started building a smart home, I used smart relays a lot, and generally different relays, for example, when I was still starting to make and experiment on Arduino, making different sensors and different devices, then of course there are classic examples when you need to take a very simple relay, the relay module itself, connect it to Arduino, and use it to control some kind of load, turn it on or off.

These relays are sold in many places and they can be 10-amp, mostly they were found for such homemade devices, or 16-amp, if you buy a little more expensive, these relays work on the principle of dry contact, that is, they simply close or open some kind of load, there are also solid-state relays, these are in fact, a relay module is made on the basis of a triac, it can only switch alternating current according to its principle of operation, and a mechanical relay according to its principle can switch any current, either direct or alternating.

At one time, when I switched to Raspberry and created, planned to create, a Raspberry-based smart home system, it was Raspberry Pi 3, I bought a special relay module of three relays and thought to use it by putting the Raspberry itself in the control panel, but of course I did not put it there, because firstly this is inconvenient from the point of view of management, and I did not have a place provided in the dashboard, of course, I have made it so that you can put a Raspberry between different machines, and it is comfortably placed there, but I do not have Ethernet there, it is not connected, accordingly, it was not possible to connect it by wire, it was necessary to throw a separate cable from the weak point panel, which in principle was not very convenient, it was also possible to pick up via wi-fi, in principle, I had a wi-fi router nearby, now it is generally located at the other end of the apartment, and in principle probably He wouldn't have been very good at fishing there.

The difference between mechanical and solid-state relays, of course, is that mechanical relays click loudly enough to be heard, while solid-state relays, by their design, by their nature, do not click at all, because it is actually a microcircuit, for example, solid-state and mechanical relays are also used in switches, so it is most often found in switches if there is one If there is a contact, then they can also put a solid-state relay, if there is more than one contact, that is, let's say more keys than one, then they already put mechanical relays, the problem with solid-state relays is that they heat up and if you place a lot of them in a closed case, it is very difficult to provide a heat sink, which is dangerous in principle.

Of course, mechanical relays have a problem that if they switch a load large enough approximately according to their nominal value, for example, a 10 amp relay will switch a 10 amp load, then they may simply stick at some point in time, which is quite dangerous if this is some kind of heater being used, and it is undesirable that it remains it takes a long time to turn on the switches, but if you put more than one relay on, then of course these relays are very small in their design and you should not apply a large load to them, even if 10 amperes are written on them.

Of course, smart sockets usually have only one relay module, and of course it's mostly for 10 or 16 amps, there are even 20 amp sockets, so it's just a mechanical relay, but sockets also have another feature that they only break one line, that is, if the socket is plugged in incorrectly, for example The phase goes directly, and 0 through the relay, then this can in some way affect the load, that is, if the load is low-current, for example, an LED garland, or some kind of lamp, then it can be powered by parasitic leads and, accordingly, it can start to glow or blink, therefore, the simplest solution is to simply turn the outlet over, then it turns out that the relay opens the phase specifically, and of course the lamp will not be able to power from zero.

The relay has a similar problem, that when you connect it, you need to carefully look at which side is the phase, which side is zero, but the relays themselves, which are called smart, of course, they almost all switch the load by analogy with an outlet, that is, they do not simply break what is connected to them, namely connect the power to the output.

This is sometimes not very convenient and practically severely limits the way the relay is used, and therefore there are options for how to redo it, cut the necessary tracks there, and something else, but first of all it is unsafe, you need to understand what is being done specifically in a particular case, so you don't really want to leave such a relay somewhere, especially in closed areas. places.

The relays themselves can work using the zigbe protocol and the wi-fi protocol, and I used and bought a lot of relays operating at 433MHz at first, but of course they all have their drawbacks, the problem with the radio relay is that they have no feedback and it is often unclear whether the relay is on or off.. I tried to control such relays by indirect signs, that is, for example, on an electricity meter, if consumption increases, then I see that some kind of powerful load has turned on, if I turn off the relay, then I see what has turned off, such relays cannot measure consumption and current, and accordingly, of course, their method of application is very limited..

Of course, there are also wi-fi sockets and relays, which almost all work through the cloud, this is Tuya or others, and this greatly limits their use, because the cloud can stop working at any moment, and this is not a good idea in a smart home, but such relays are connected once to wi-fi if you need to reconnect, then in principle it is quite simple to save the same network name on the wi-fi router, then it immediately connects no matter where it is located, that is, behind the ceiling, in the wall or somewhere else, if hidden.

If this is a zigby device, then of course they have a plus, they work directly through the gateway, they do not need the Internet for this, but there is a problem that if you need to reconnect all the devices, you will need to get this relay from where it is located and, accordingly, only by pressing the button on this relay, you can switch it over.

There are practically no solutions that allow, for example, to switch this relay into pairing mode by several consecutive turns on, but for example there are other devices, these are LED strip drivers and some light bulbs that provide for such a mode in advance and you can turn them on there 5-6 times in series, they then switch to pairing mode, and therefore the best solution is of course this means using some kind of relay, mostly wi-fi, which allows you to redo them, or put them into direct connection mode, such as the so-called DIY mode, and then you can directly connect to these relays at the IP address in the local network, they can work independently, some can be flashed to alternative firmware and they can also give their status via MQTT, of course, the way to use these relays becomes very limited anyway, for example, to find out the status most often, of course, you have to access the web.-address and receive the current value of this relay, but at least these relays will not depend on any clouds, and therefore they will work more reliably.

I have one relay from Sonoff, which makes it easy to switch it to a local network mode, but I don't even use it because it's not very convenient and I mostly use smart sockets or smart switches everywhere.

Automation in a smart home should be useful and create additional comfort, but sometimes everything goes wrong… The reasons for this, and how to configure everything, see on my channel.