Structure of alarm clock

An alarm clock comprising a housing, a clock module and a control circuit mounted inside said housing, and a rack adapted for receiving said clock, said control circuit comprising a solenoid switch, said clock module comprising an alarm circuit, said housing comprising a casing and a back cover covered on said casing, said casing comprising a battery case, which holds a battery, which is electrically connected to said clock module and said clock control circuit, an electromagnetic valve holder suspending above said battery case, a peg spaced between said electromagnetic valve holder and said battery case, an electromagnetic valve mounted in said electromagnetic valve holder, a hook turned about said peg and having a fixed end pivoted to said electromagnetic valve and a hooked free end, and a bottom hole, said back cover comprising a back opening, a battery lid covered on said back opening and having a locating loop at an inner side, a bottom hole matched with the bottom hole of said casing, said rack comprising an upright back wall having a hang hole for hanging, a horizontal bottom wall perpendicularly extending from said upright back wall at the bottom, two upright side walls bilaterally connected between said upright back wall and said horizontal bottom wall, and an upright post raised from said horizontal bottom wall at the center, and a magnet fixedly mounted on said upright post at the top, wherein when a set alarm time comes and said housing is disconnected from said rack, the alarm circuit of said clock module is driven by said control circuit to alarm, and said electromagnetic valve is simultaneously driven by said control circuit to turn said hook, causing said hook to hook up the locating loop of said battery lid;

• when said housing is put in said rack by inserting the upright post of said rack into the bottom hole of said casing and the bottom hole of said back cover during the ringing of said clock module, said solenoid switch of said control circuit is induced to turn off the alarm circuit of said clock module, and to cut off power supply from said electromagnetic valve, causing said hook to be released from the locating loop of said battery lid.