Smallest footprint question

Hi all, having great fun getting back into programming again with the help of my new Arduino.
A project I'm working on needs to combine a really small footprint with an rf transmitter and power supply.

Size at the receiver end isn't such an issue and I was planning to use my current Arduino Duemilanove 328 for that....

but ...at the sending end I want everything as compact as possible.
Was thinking of a Nano combined with one of the small rf transmitters but a 9V battery would add too much bulk. Are there other (portable) power options I could look at that would power the setup? Something like a thin lithium battery would be great but not sure how to connect / what type etc etc.
Sadly, as ever budget is a limiting factor. (or I would look at the Lilypad)
Any advice very much appreciated.

2MuchNFO

What bandwidth and what duty cycle do you need?

Many thanks for replying and for flattering me with the assumption that I know what the heck I'm talking about :slight_smile:

My program currently just uses the USB link to send a simple serial sensor reading as a string to a Processing sketch.

I want to replace the cable with something like this...
http://www.coolcomponents.co.uk/catalog/product_info.php?cPath=25&products_id=186
..if possible ....and pick up the sensor data within a simple serial string of data, using another arduino....unfortunately the electronics side is much newer to me than the programming side and so I've been making use of this forum and experimentation so far.

Distance that the signal needs to reach is fairly minimal, no more than 30 feet or so.

However in answer to your question....err....no idea I'm afraid :-/

Sparkfun and many others have LiPo batteries and chargers for them. They connect like any other battery. Typically, they are limited to 3.7 volts, so you'd want one of the 3.3V Arduinos and a 3.3V transmitter.

check this project out i think its just wat you want
http://cafe.jeelabs.net/lab/jn4/

Thanks for the link. Need to keep it pretty simple as it's all new to me at the moment. I probably need 6 separate sensor inputs and this only seems to have 4? I'm currently using all 6 Analog inputs on the Arduino.

if you are using the jeenode and not use wire/i2c
you can also use SDA and SCL as analog inputs

Thanks I'll take a look - To me honest I havent played with I2C at all yet. Too many other new wonders to explore in the Arduino world for me so far