Hello,

I am looking for a smart Wifi-enabled relay that can for a predetermined amount of time (e.g. 3 min) turn off the power supply of a connected device. Any idea what is name of such relay and any manufacturers? The idea is that upon pressing a button on a mobile app, the relay would switch off the power of the linked device for say 3 min, and then in 3 min the device would have power again.

Thanks

 

There are a wide range of IoT outlets available. Here's one I like:
https://www.koogeek.com/p-p1.html

There are some that are very inexpensive:
https://www.prairiegrit.com/product/wyze-wlpp1cfh-wi-fi-smart-plug-2-pack/

With one of these smart plugs, the rest is software. I don't think you'll have any trouble finding an app that can do exactly what you want.

 

Thanks but these are standard smart plugs. They turn on or off the power supply. They do not turn off the supply for a temporary pre-defined period upon pressing a button on a app on demand.

 

I use SONOFF products but there are many on the market. Most of the "relay modules" have on/off functions but you need off/on which most cannot do. Also you need "inching" function which most do. Most modules have a "normally off" relay. Choose a module with unconnected relays like this. MHCOZY This gives you both "normally off" and "normally on" functions.
MHCOZY-2 Here is the smaller two relay version. For some reason I can't find SONOFF's 4ch module which is what I use.

Set up the relay in "inching move". (I know this is backwards but keep reading) With inching you push on and the relay will turn back off in some amount of time. (3 minutes) Using the Normally Closed part of the relay you will get the opposite effect.

When looking for a wireless relay start out with SONOFF, MHCOZY, or SHELLY.
Do not get anything with a "Z" in the name. You are looking for an WiFi network not a Zigbee network.
I use eWeLink software on the phone to talk to them. With no account you can control the relay from PC or phone on you network but not from work. Setup a free account and you can connect from anywhere.

Another option. There are many modules that will work but backwards for you. In most modules there is an option for "on at power up". I have not tried it but it might invert the inching function. (probably not)

Another option. The eWeLink software has an option to write simple code. (The inching function works inside the module and will continue to work even when the network is down.) With eWeLink the code function work only when your house is connected to the internet. I have code: "if SunUp then FrontLight=off" and "if SunDown-15minutes=FrontLight=on". There are functions with timers. I don't have the manual in front of me but something like "If module3 is off=start timer3 at 3 minutes" and "If timer3=0 then module3=on". I think I could take a very simple WiFi realy and make it work with eWeLink "scenes".

RonS.

 

Many thanks. That was very helpful.

 

In a relay module the Inching Function comes from the need to control garage doors and curtains. There are motors that raises and lowers the curtains. From remote it is hard to "curtain up" which turns on a motor, then 3 seconds later "curtain stop". So we program Inching=3 seconds. Now when you say curtain up it moves for 3 seconds and stops. It is almost impossible to get a motor on sent then a motor off sent in under 3 seconds.

I use the function for Garden water on, where inching is set to 30 minutes. If we use ON and OFF functions and the network fails it is possible that ON was sent and OFF failed. This is very bad for watering. I set all water to Inching=30 minutes. Then send a ON command that does not need an off command. If I want 10 minutes, I can still send an OFF in 10 minutes or if I want 40 minutes I can send ON now, ON later and then OFF. The inching can just be a backup just in case the OFF is lost.