An alarm clock is a clock with an alarm device. The alarm clock can not only indicate the time, but also send out sound signals or other signals according to the time scheduled by people. The movement structure of the alarm clock is mainly divided into two categories: mechanical type and quartz electronic type. Other types, such as transistor balance spring type and tuning fork type, are rarely used. Usually, the desktop alarm clock used on the table is called a travel alarm clock, which is mainly used for travel. The daily error of the daily mechanical alarm clock is generally within 120 seconds/day, and the daily error of the quartz electronic alarm clock is generally within 0.2 seconds/day. There are many kinds of alarm clocks, mechanical and quartz. Since it was invented by people using the principle of the pendulum, it has become an indispensable item in people's lives.

Mechanical alarm clock:

The mechanical alarm clock uses a spring to store energy and is made of a high-manganese steel material. The mechanical alarm clock increases the angular velocity through many levels of gears, and through the reciprocating swing escapement, a structure with a natural vibration period to achieve timing requirements. The spring-like hairspring used in the escapement is a constant-elastic alloy, an elastic element whose mechanical properties are less affected by temperature.

Quartz alarm clock:

The quartz alarm clock can also be called a crystal vibrating electronic watch, because it works by using the vibration phenomenon of the crystal. When the crystal piece receives an external applied voltage, it will have the properties of deformation and expansion. Conversely, if the crystal piece is compressed, electricity will be generated at both ends of the crystal piece. Such a property is also seen in many crystals and is called the piezoelectric effect. Quartz alarm clock is to use the periodic continuous "vibration" of the crystal, to bring us accurate time.

How to choose an alarm clock:

(1) Check the appearance of the alarm clock first: pay attention to whether the color of the clock shell of the alarm clock is bright and uniform, without peeling, discoloration and scratches. Pay attention to whether the scale of the alarm clock is even and the writing is clear.

(2) Check the sensitivity of the alarm clock: an alarm clock with high sensitivity lasts for a long time.

(3) Check the sound of the alarm clock: place the clock face left, right, front, back, up and down. If the sound is the same in all directions and in all directions, and there is no noise, it means that the alarm clock is normal. The alarm sound should be clear and loud.

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