What are the characteristics of alarm clock?

An alarm clock is a kind of clock with an alarm device. It can not only indicate the time, but also send out sound signals or other signals according to people's predetermined time. The movement structure of alarm clock mainly includes mechanical and timely electronic. Other types, such as transistor hairspring and tuning fork, are rarely used. They are called desktop alarm clocks that are usually placed on the table and travel alarm clocks that are mainly used for travel. The time error of daily mechanical alarm clock is generally within 120 seconds/day, while the time error of timely electronic alarm clock is generally within 0.2 seconds/day.

There are many kinds of alarm clocks, mechanical and timely. Since people invented it by using the principle of pendulum, it has become an indispensable item in people's lives.