Digital stopwatch timer

Digital stopwatch show the time as numbers. On digital stopwatch use two numerical display formats:

    24-hour notation with hours of 00-23;
    12-hour notation with AM / PM indicator, with hours displayed as 12AM, followed by 1AM-11AM, followed by 12PM, followed by 1PM-11PM (notation which is commonly used in the United States).

Due to the need for phone calls or blind people, there are stopwatch that show time sound or spoken language (eg, "Now is exactly twelve hours and thirty five minutes), or acoustic signals (eg, the number of blows ring shows the hours at that point) .

Text stopwatch showing the time in the form of visual language. For example, in English, 12:35 may be displayed as "Twelve thirty-five." Some versions of these watches use a lot closer to measuring, for example, "About twelve-thirty,"
The division according to the stopwatch timing
Mechanical stopwatch mechanism.

The largest number of stopwatch timer is built around some type of oscillator, which changes the position of the endless series of periodic changes, which allow a permanent and stable reference frequency. The periods of this oscillator are counted and converted at a specific time on the stopwatch.

    Mechanical pendulum stopwatch used as an oscillator, which controls the rotation of a series of gears that measure time.

    Crystalline quartz stopwatch use an electronic crystal oscillator and frequency divider or counter. Most crystal watch uses battery-powered oscillator 215 Hz = 32,768 Hz.

    Atomic stopwatch use the microwave oscillator (maser) tuned energy changes of elements such as cesium, rubidium or hydrogen. They are the most accurate stopwatch. The cesium atomic stopwatchs are now used as the official time keepers unit.

    Electric stopwatchs measure periods of 50 or 60 hertz alternating current, whose stable average frequency control specific plant.

    stopwatch Radio periodically activates a built-in radio receiver to automatically adjust the time by radio signal. Radio signals are usually generated by an atomic stopwatch in radio station.

    Sundials use the apparent rotation of the sun around the Earth as your reference oscillation.


A stopwatch in homes and offices, small to wear on your wrist, a large are in public places, eg in railway stations or churches. Small watches are often found in the corner of the computer display or on mobile phones.

The main purpose of the stopwatch is not always to "show" time. He used to "control" or alerts on specific events, such as: alarm stopwatch (alarm stopwatch), sat on the VCR, or a time bomb.

Virtually all computers depend on accurate time signal to be synchronized processes taking place. Some computers also displays the time and date and serve as alarms, triggers certain procedures and events or simply show time.
Navigation

Precise navigation of ships depends on the capability of measuring longitude. Latitude is relatively easy to determine through celestial navigation, but the measurement of longitude requires accurate measurement of time. This was one of the main reasons for the development of accurate mechanical stopwatchs. The first marine chronometer extremely accurate made by John Harrison in the 18th century. "Midday top" in Cape Town still shot gives a precise signal that allows ships to check their chronometer.