竞赛抢答器(模拟)的原理图，逻辑开关K0～K7代表竞赛抢答按钮0～7号，当某个逻辑电平开关置“１”时，相当某组抢答按钮按下。在七段数码管上将其组号(0～7)显示出来，并使微机扬声器响一下-Contest for (analog) schematics, logic switch K0 ~ K7 represents Contest for buttons 0-7, when a logic level switch is set to " 1" , quite a group answer button is pressed. In its seven-segment digital tube group number will be (0-7) displayed, and make it sound computer speakers