电路由AT89C52，4个数码管，两个按键构成。两个按键用来实现密码的输入，并在数码管上显示输入的数字。输入数字正确，数码管显示OPEN，错误时数码管全部显示0。连续3次错误，熄灭数码管同时报警3秒，3秒之后恢复到初始状态。-Circuit by the AT89C52, 4 digital tube, constitute two keys. Used to achieve two key password input, and show up in the digital control input figure. Enter the correct figure, digital display OPEN, digital tube, when all the wrong show 0. Consecutive 3 times error, digital tube at the same time the police put out three seconds, three seconds after the return to the initial state.