... 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 ... through the output transistors, resulting in low distortion but high heat and just 20 percent efficiency. Class B amplifiers ... to 50 percent. Class D amplifiers, which use ultra-high frequencies to regulate switching operations, offer efficiencies of up ...