Each buzzer consists of an Arduino Pro Mini 3.3 V, a nRF24L01, and of course a big pushbutton on the top. Each one is powered by a 110 mAh 3.7 V LiPo battery, though [Flute Systems] notes that the ...

The main change – the control electronics were replaced by an Arduino Pro Mini (16Mhz model). He soldered all the modules on a prototyping board and, although admittedly a bit heavy, the little ...