| The alarm clock is a special type of clock, which generates sound or a light signal at a specific time. The basic purpose of such clocks is waking up the owner in the morning. The alarm clock also can be used as a “Reminder” or timer.
History:
Graded sticks made of resin mixture and sawdust to which a load was tied with threading was used in ancient China as alarm clocks. A stick was ignited, and completes burning till the thread falls down on the metallic stand.
In ancient Greece, similar devices were used for water clocks.
The mechanical alarm clock was built by American Levi Hutchins in 1787. The device used to issue a sound signal only at 4:00. French Antoine Redier patented the alarm clock with the provision of setting it for any time in 1847.
Firm Westclox in 1908 had offered an alarm clock called “Big-Ben”. The entire body of the clock served as a bell, due to which the sound of the alarm clock was loud.
Devices which will provide a reliable wake up call to a human being are under development. Basically two problems were trying to be solved:
How to prevent the owner from sleeping again by switching off the alarm clock.
How to wake up someone smoothly without pain.
One such device got the Noble prize in 2005.
Mechanical alarm clock
Apart from the common clock mechanism, the mechanical alarm clock has a ringing mechanism, which is set in action by a separate spring and acts as per the principle of a key doll. This mechanism has two independent interlocks:
The axle of the clock wheel has an additional disc with a notch, connected with an additional “ringing” arrow. When the clock arrow coincides with the ringing arrow, the projecting part on the clock wheel falls in the notch, and the interlock releases the ringing mechanism.
The second interlock is linked with a button to enable the switching off of the ring any time.
Electro-mechanical alarm clocks use a similar mechanism.
There are alarm clocks with a radio receiver with digital adjustment. Electronic alarm clocks could solve the problems which were not solved by the mechanical ones:
The wake up procedure was improved:
On pressing the button from on top of the alarm clock, the “Give me sleep” mode starts. After 10 minutes break has been given to the owner, the alarm again is activated. The alarm clock fully gets switched off with a small button, which is not easy to press automatically;
Music instead of a ring (a melody recorded in the memory of the alarm clock will be played or a radio receiver or player will be switched on);
Gradually ascending ring sound.
Ringing time is set very accurately – up to one minute.
Many clocks provide the settings for two or more alarms at a time.
The mechanical alarm may ring after a 12 hour setting. For an electronic alarm clock, this duration is increased up to 24 hours.
The alarm is practically available in all electronic clocks. The alarm function is frequently included in players, Televisions, radio receivers, mobile phones etc.
Recommendations regarding the selection of alarm clock
The alarm clock should be inexpensive, however unfortunately purchased alarm clocks may be rubbish. These recommendations will help you in the selection of a suitable clock.
Be sure there is a sufficient sound level so it will reliably wake you up. Look for a suitable melody/sound for you. Think whether you require an increasing sound or not.
If you are buying an electronic alarm clock for basic use (for waking up in the morning), the ideal algorithm is: for wake up in the morning, in the evening you switch it on; when you press the button on top of the alarm clock, it gives some snooze time; finally the alarm clock stops by pressing a smaller button; if nobody reacts to the alarm for a long time then it gets switched off automatically. Such alarms will not disturb neighbors, when you are away, and will not wake you up when there is a possibility to sleep more.
If you are buying a mechanical or electro mechanical alarm clock, then be sure that it ticks calmly. The alarm clock based on cheap mechanisms ticking once every second may disturb you getting to sleep. This is true for any clock located in the bedroom.
If the alarm clock is combined with a radio, the speaker of the switched off receiver should not generate any sounds. Any sound is a feature of a non-reliable scheme, there is a risk that they may develop to a calm but persistent mumble.
For alarm clock working with a current, a reserve battery is required and a cheap spare alarm also required. Even if the power fails, the clock should not be stopped.
If the alarm clock works by battery, do not replace it with rechargeable batteries. Recharge batteries works for a long time, but at the same time due to the high current of self-discharge they require frequent charging.
Alarm clocks in cinematography
In the film “Groundhog Day” a scene was to be shot, where the irritated Phil breaks the alarm clock into pieces but the shot was not cleared as Phil could not break it. Due to the impact of Murray, the clock developed cracks and as a result, the shooting team was forced to hit the clock with a hammer. In spite of this (shown in the film), the clock did not stop ringing.
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