Design a four-way buzzer, host after press the start button, the competitors can vies to answer first, vies to answer first time with a countdown digital tube display, after the stipulated time someone vies to answer first, thunder ringing and others not vies to answer first, the host through the plus/minus button of vies to answer first contestant scoring, two players scoring with digital tube display, in excess of the prescribed time, the contestant vies to answer first is invalid, proteus simulation files, circuit diagrams, etc