how to make small microcontrollers

Hi I have been playing with Arduinos for a little bit and want to extend my experience to building my own,

I have a project, basically an remote buzzer, using RF boards such as http://www.instructables.com/id/RF-315433-MHz-Transmitter-receiver-Module-and-Ardu/

on the tx, I want a small portable button, that a person can carry around and the battery should last a long time, like weeks,

on the rx, a simple buzzer when the TX button is pressed, the buzzer pin goes to HIGH, and when not pressed stays low..

Very simple logic and only need 2 I/O digital pins on both RX/TX

Where should I begin my research, and on what microcontroller chip? And hopefully I can transfer my knowledge of arduino to this project.

Thanks

I would begin here: Nick Gammon

You will likely have responses regarding using the Attiny85 or other tiny series, and on the surface this would seem like a great idea. However, while a tiny85 can be purchased for around $1 USD, a full-blown Atmega328P-PU is only about $3 (prices in 25 qty so one-sies will be more.). However, you can program the Atmega 328 just as you would an UNO ,,and no code changes or memory concerns exist... Develop on an UNO and directly port to the naked chip using either a serial USB adapter with bootloasder OR just overlook the boot loader and use ArduinoISP. You also have the option of using a crystal or the internal RC 8MHz.

Some ideas: Flat-duino

Ray

So - you mean a wireless doorbell?

Thanks Mr. Burnette, I appreciate your help. Yes, I agree with going with the MEGA but I always like to minimize as much as possible for overall portability and design, cost and in this case potential power saving as I figure the AtTiny85 would be more power efficient.. So I went ahead and ordered some AtTiny85s Thanks again for pointing me in the direction.

Paul, yeah, that would be too simple!! Doing it as I want to build my own to maybe repeat the signal around a big house and potentially be addressable to be two way buzzer.. So I can buy as you said, but that would be boring...