My design of the ULRS mini board:
ULRS Mini project page: http://www.itluxembourg.lu/site/apmplane/ultimate-lrs-mini/
Small size 3.9cm x 5cm
Onboard TO-220 regulator
Uses through hole components for simple build
Transmitter JR slot compatible connections
Fits in TX or use as a compact RX
Header pin for serial: gnd,rx,tx,5v
Header pin for button and buzzer: gnd,button,buzzer,5v
I've included a build cheat sheet above to help you get started