The project was tricky because at the beginning I used the 3v ProTrinket thinking that since the transmitter nas a 3v regulator it will be a good fit. Unfortunately I was wrong. It did work
But it was unstable and the range was not good around 30 feet. Then I realized that it worked much better with arduino Uno so I switched the trinkets and it's very good now. I use daily to stream internet radio from the Raspperry Pi. The included 500mAh LiPo battery lasts for a whole day of transmitting or maybe longer because I didn't test it longer since I plug it in over night to usb power adapter.