在日常生活和工作中，家庭和工作的安全、单位的档案、财务报表和一些个人数据大多采用加锁的办法来保存。本密码锁主要由密码设置电路、发射电路、解码电路、显示电路、电源电路五部分组成。在本密码锁中，按要求按下按键，即输入正确的密码，NE555电路就能正常工作，经解码电路解码，继电器吸合，发光二极管发光；密码不正确的时候，发光二极管不能发光。采用本设计可以很好地实现防范功能。

In daily life and work, family and work security, unit files, financial statements, and some personal data are mostly kept in a locked way. The coded lock consists of five parts: cryptographic setting circuit, transmitting circuit, decoding circuit, display circuit and power supply circuit. In the coded lock, by inputting the correct password, the NE555 circuit can work normally. After decoding by the decoding circuit, the electric relay closes and the LED lightens; if the password is incorrect, the LED cannot shine. This design can achieve the safety prevention well.