Idea: Replace a light switch with an NFC enabled Arduino unit.

Hi all :),

I recently discovered Arduino and had an exciting idea. I was wondering if I could use an Arduino unit with the NFC shield to control the light in my room. I have a Samsung Galaxy Nexus phone which has a NFC chip in and thought this might be pretty cool. I'm somewhat tech savvy but new to all this and was wondering if you guys could give me your opinion on my idea and maybe shed some light on my initial queries.

Most importantly: Is this do-able? The unit would replace the conventional switch on the wall (with possibility manual override if it fails). If so is the Uno the best choice?

Fundamentally, does the Arduino require an attached computer? It seems you can save your code onto the device but I was thinking about having it connected to a Raspberry Pi to allow for tweaking if possible.

Thanks
Adam

You want to press your phone against an Arduino to turn on the lights? If your hand is that close to the Arduino, wouldn't a big pushbutton be more convenient?

Thanks for the reply! You are not wrong, however this is just the basic idea.

My plan would be to expand on this, to have the arduino become a controller for all the electronics in the room. I got the idea from a hotel where they have a similar system in place.

One issue I thought of is that the power for the light is 240V and the arduino uses 3-5V. I'm guessing I would need some sort of electronic switch and a transformer in between? If that's correct wouldn't it create a lot of heat?

Adam

Is this do-able?

Absolutely doable.

Oh and the main reason for using NFC is because my phone has the NFC 'beam' mode.

The finished product might work a little something like this:
Walking home, open app on phone, check off things I want on when I get in (pc,stereo, etc), adjust settings like how bright the lights are, room temperature, walk through the door, touch phone, bang all done, look like a boss in front of guests, relax with beer 8)

Well that's the dream..

Adam

dhenry:

Is this do-able?

Absolutely doable.

hughesy:
One issue I thought of is that the power for the light is 240V and the arduino uses 3-5V. I'm guessing I would need some sort of electronic switch and a transformer in between? If that's correct wouldn't it create a lot of heat?

Not heat especially, but it would create a potentially lethal combination of high and low voltages. Unless you have practical experience of working safely with mains voltages and electronics, you should consider using only commercial parts for the actual switching - and that will bump up the price and space requirements substantially.

A relay is all you need. You should not have any trouble finding information on switching mains voltage with an arduino and a relay. It is an electronic switch just like you said. Like a regular light switch that is flipped by a smaller current instead of your finger.

The problem with this idea is getting power for the Arduino.
A light switch is fed with 2 wires which go in series with the light being switched.
When the switch is off, then there is 240 V across the switch which you can power something with.
When the light is switched on by a relay or whatever, there is no voltage avalaible to power whatever is doing the switching.
You have to include a battery somewhere, plus a method of charging it .

The arduino could be wired in parallel to the light and switch so that it can still receive power even if the light it switched off. I personally am this far only comfortable to using prefab power adapters though so I cant help out much more than that.

Thanks for the replies everyone, have some karma!

Got a bit of research to do, it looks like I'm going to need a solid state relay.