... with antenna3,with echo4,with LCD digital screen,size:30x22 mm5,with the function: calendar,alarm clock,showing song lyric,etc.6,with remote control ... but high heat and just 20 percent efficiency. Class B amplifiers divide the waveform reproduction between two alternating output ... , yielding up to 70 percent efficiency. Class A/B amplifiers allow the switching between transistors to overlap slightly, ...