Sending and receiving data cheap

I'd say forget about Instructables. It can be very misleading at times.

Edit:-
Have to eat my words here as the one I refer to was actually posted in Instructables as well.
Link below......

Check the Arduino tutorials and forums on "mesh networking".

There is a bloke from down here who has a write up about his cattle watering system. See if I can find it for you.
Interesting reading.

http://www.instructables.com/id/Simple-Arduino-Wireless-Mesh/


Note....most on Arduino forum will throw up if you present drawing in the Fritzing format.

 

I attended a Texas Instrument seminar a few years ago where they were demonstrating their low-power wireless Bluetooth technology coupled with (what else?) a TI MSP430 microprocessor. All of us in attendance received a little coin-cell operated Bluetooth thingy with a temperature sensor. At the end of the presentation we were invited to "light up" all of our thingys. The presenter had an app that read the temperature of each thingy in the room and displayed the temperatures from each device on a large digital projection screen. Pretty impressive, I thought. I still have the thingy they handed out, but haven't found my "round tuit" to pursue this technology any further at home. Couldn't convince the TI rep I needed at least TWO of their thingies for further evaluation. But I think TI sells most of these "demo" thingies online.

Point is, a mesh network is the way to go with multiple sensors, all operating independently. I purchased four XBee modules and shields for my Arduino Unos, but haven't tried to network them yet. This was a couple years ago, and at that time I only needed a single two-way comm path. Thanks, @Bluejets for the Instructables link. I usually cringe when anyone here says, "I found this neat circuit on Instructables..." because it is usually followed by, "...but I can't seem to make it work." You DO have to be careful reading the content of any Instructable. So much of it is just crap. But that one seems well-thought out and successful. @patchie should review it and come back here with more questions. And please ditch the Fritzing stuff... we are mostly adults here and work with real schematics and block diagrams.

 

Tayda have a helpful PDF
http://www.taydaelectronics.com/datasheets/A-2861.pdf

I have had limited success with these modules due to noise, they pick up lots of stray signals, may be something to remember if it's not working correctly for you.

 

No, just Arduino for receive and Atmega8 for transmit.
It did improve some when I used the 3.3 volt on the Arduino rather than the 5 volt to power the receiver.