cheap wireless communication

hi
i am in the middle of designing a very simple door alarm.
please can someone help me decide which way to proceed on the wireless side.(data to be transmitted simple on off) please advise me on the cheapest option. distance max 10m.

also how would i be able to play music through arduino.
thanks in advance

i am in the middle of designing a very simple door alarm.
please can someone help me decide which way to proceed on the wireless side.(data to be transmitted simple on off) please advise me on the cheapest option. distance max 10m.

Modify a wireless door bell.

also how would i be able to play music through arduino.

You could have the arduino operate a transistor which which controls the power to a gizmo that can play music.

You could have the arduino operate a transistor which which controls the power to a gizmo that can play music.

Something like this...

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1289929542

The Arduino Uno has three fairly large mounting holes. You should be able to play music on one side of the Uno and get the sound to go through one or more of those holes and appear out the other side.

Hmm...

Even though all you wanted to is a simple on/off controller, I'd imagine you'd also want this alarm to be some what reliable, correct? This means, you can't just use a simple carrier-only transmitter, and some kind of modulation and coding is needed (i.e. FSK).

So I'd just pickup a pair of RF link transmitter/receiver, like these ones:

They are pretty darn cheap!

Ian, that was too funny!

The sparkfun Rx/Tx works well, easy to program to send a message from the Tx to the Rx using virtualwire:

See the "simple remote for granny" to make the Tx side sleep in between transmissions if you want it battery operated, build it around a 3.3V ardweeny & power it with a 3.7V LiPO battery, recharge it once a month or so. Or 3 AAs will also work. Bring power direct to VCC pin, no regulator to suck your battery down.
http://www.solarbotics.com/products/kardw
(click resources, manual, easy to assemble)

On the Rx side, search the Tone tutorial, make it play whatever song you want thru a little speaker (or an amp and a bigger speaker) when you get a message in.

<$30 in hardware, mount both sides on some perfboard.

THANKS GUYYS JUST WHAT I NEEDED

I've just ordered the RF transmitter/receiver from the bottom of this page: http://www.bitsbox.co.uk/sensors.html#rf

You dont need to waste an Arduino on a dumb ON/OFF wireless sensor, see
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1293839127
Dumb Dirt Cheeep Wireless Environment Sensor
Use the first example, and have the door switch in series with battery.

The TX is less than $1 of parts plus your module. For longest battery life, have the TX turned off in the state the door spends most of its time.