Hi, I am new with arduino. Recently I came up with the idea of make a home automation system for my own. Suddenly I realized, I don't know how many relay can used by a single "arduino uno" or other arduino.
Please help me. I need details.
1 which arduino I should use?
2 how many relay I can use?
3 if anyone have any better idea for home automation system, and if it is possible please share with me.
An opto-isolated relay uses no more Arduino current than an led, since that's exactly what they are, if you wire them to use an external supply for the relay coil.
Not sure exactly what they draw, just a couple of mA according to this (bottom left of scheatic), so you can run a large number before you draw significant current. But you really do need a separate supply to the relay coil a) for isolation and b) so you're not powering the relay from the Arduino, only controlling it with tiny current.
Basically you can drive as many as you want. If you want more than the number of pins on the Arduino simply use a chain of shift registers to expand the output.
Grumpy_Mike:
If you want more than the number of pins on the Arduino simply use a chain of shift registers to expand the output.
Thank you for you reply.
I am new with arduino. So I don't know lots of things.
I want make a home automation system. I want control all af my house staff through my Android phone.
But I think my uno can controll only 10/12 relay.
"You are speaking about expand the output."
I don't know how. And I don't know how this expanding going to work for my project.
If u have anything that show me how? That will be very helpful for me.
Once again, thank you.
I don't know how. And I don't know how this expanding going to work for my project.
Have you read How to use this forum it will tell you what to do with answers. In this case I advised you to use a shift register so I would have expected you to use google to look up:-
Arduino shift register.
You would have found this link:- https://www.arduino.cc/en/tutorial/ShiftOut
Here's a relay card I offer, the coils are controlled by putting data into a shift register. You can daisy chain the cards, or you send data to each one independently.
http://www.crossroadsfencing.com/BobuinoRev17/
As an Uno shield
Driving 120V LED light strings
Course, this does require all your power sources to be controlled from one place. Is that what you want? Or do you want 1 and 2 relays scattered around the house? Perhaps a bunch of Arduino equivalents connected up via RS485 to a master, with each controlling 1 to several relays?
I want make a home automation system. I want control all af my house staff through my Android phone.
But I think my uno can controll only 10/12 relay.
I'd suggest you look into some of the existing home automation systems. With [u]dimmer switches[/u] and [u]controlled power outlets[/u] like these you won't have to re-wire your house, and the dimmers & switches can still operate locally/manually.
With these systems you don't directly communicate with the switches/outlets over the Internet or the cell phone network, but you can get (or build) a "bridge" or "hub" that communicates with the switches/outlets and with a Wi-Fi or the cell network, etc.
If you really want to build something yourself, you can build a compatible controller with the Arduino. But, you will have to make it compatible with whatever protocol your switches/outlets use.
And, if you choose one of the standard home automation protocols it will be easier to upgrade or modify your setup.
[u]SmartHome.com[/u] sells lots of home automation products if you want to get an idea of what's available.
Grumpy_Mike:
Have you read How to use this forum it will tell you what to do with answers. In this case I advised you to use a shift register so I would have expected you to use google to look up:-
Arduino shift register.You would have found this link:- https://www.arduino.cc/en/tutorial/ShiftOut
No I didn't read How to use this forum before your answer.
And yes I did use google for find some information about Arduino shift register.
However, thank you.
Before you connect ANY mains powered devices to an Arduino or relay board, make sure you understand the concepts of isolation, grounding and PCB creepage.
The alternative is rarely pretty.
Yes I did search, but I think I didn't search the right way.
After creating this post I found this
Look I know I am not as fast as you are. But I can use google. The real problem is you can't understand my problem.
I am from Bangladesh. From my country I can't order ebay.com or amazon.com or any other shop otside my country. Sometimes I even couldn't find all parts. So I need find an alternative way almost every time.
I know you ar busy lot more than me. But I am really happy for all of your help.
The real problem is you can't understand my problem.
And who's fault is that?
From my country I can't order ebay.com or amazon.com or any other shop otside my country.
It would be good to state these things in the first post.
However I am not sure how this is going to help us help you. How do we know what parts you can get in your country unless you tell us where you can get parts.
It's ok.
Actually I want make a home automation system, which I want control by my mobile phone. I searched on google, then I found some post about arduono. Likely I found a clone on a local online tech shop. From Then I am trying to gather as much information as I can.
Now I have
1: arduino
2: relay bord
3: 3.3/5 volt power
4: bt hc 05 (without base board)
