The idea of this project is to simply create audio capturing unites, that transfer sound over FM. Using multiple transmitters, we create a receiver device that acts as an output for different audio channels, and which also has a mixer. I would love to add recording functionality as well, if I managed to. Below is a diagram illustrating the simple system architecture:
My initial thought was to capture and manipulate live outdoor sounds (tree leaves, car wheels, ..etch) however due to sound quality and signal transfer of FM available ranges with this shield (50 ~70 m). I am now testing with capturing unpredictable sounds, from very close objects.
Below are images from testing the transmission from a tree as well as testing for different sound reflection techniques: 
Right now, I need to:
1. Find a better way to design a compact transmission unit that is small, independent, with good powering solution (one option is to use Arduino Fio and Lituhum battery , another even more compact option is to use ATtiny85 chip
2. Define interesting sounds for personalized channels
3. Make sure the analog mixer will actually work nicely with these generated sounds (I really want to rely on a variable resistance technique to change sound, without using any interface)
4. Amplification, if needed..
If all the above went well, I should be able to finalize it and build the radio 
— you just need to wish me good luck!
Happy Holidays
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[...] have been following the checklist I set for myself on the last post, which starts by shrinking the circuit. Before I start, I should tell you that I did a lot of miles [...]