a 555-based project that can be used as mailbox alarm. By suitable mounting of the LED and the phototransistor, the circuit is able to detect when a letter is dropped in your mailbox.

在ubuntu 终端输入“ ./可执行文件 mail.sohu.com” 可向搜狐邮箱取邮件-In ubuntu terminal input. " / Executable file mail.sohu.com" can take the message to the mailbox Sohu