Stopwatch
Encyclopedia
A stopwatch is a handheld timepiece designed to measure the amount of time elapsed from a particular time when activated to when the piece is deactivated. A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stopclock.
The timing functions are traditionally controlled by two buttons on the case. Pressing the top button starts the timer running, and pressing the button a second time stops it, leaving the elapsed time displayed. A press of the second button then resets the stopwatch to zero. The second button is also used to record split times or lap times. When the split time button is pressed while the watch is running, the display freezes, allowing the elapsed time to that point to be read, but the watch mechanism continues running to record total elapsed time. Pressing the split button a second time allows the watch to resume display of total time.
Mechanical stopwatches are powered by a mainspring
, which must be periodically wound up by turning the knurled knob at the top of the watch.
Digital electronic stopwatches are available which, due to their crystal oscillator
timing element, are much more accurate than mechanical timepieces. Because they contain a microchip
, they often include date and time-of-day functions as well. Some may have a connector for external sensors, allowing the stopwatch to be triggered by external events, thus measuring elapsed time far more accurately than is possible by pressing the buttons with one's finger. The first digital timer used in organized sports was the Digitimer, developed by Cox Electronic Systems, Inc. of Salt Lake City Utah (1971). It utilized a Nixie-tube
readout and provided a resolution of 1/1000 second. Its first use was in ski racing, but was later used by the World University Games in Moscow, Russia, the U.S. NCAA, and in the Olympic trials.
The device is used when time periods must be measured precisely and with a minimum of complications. Laboratory experiments and sporting events like sprints
are good examples.
The stopwatch function is also present as an additional function of many digital wristwatches, cell phones, portable music players, and computers.
Mechanical stopwatches are powered by a mainspring
Mainspring
A mainspring is a spiral torsion spring of metal ribbon that is the power source in mechanical watches and some clocks. Winding the timepiece, by turning a knob or key, stores energy in the mainspring by twisting the spiral tighter. The force of the mainspring then turns the clock's wheels as it...
, which must be periodically wound up by turning the knurled knob at the top of the watch.
Digital electronic stopwatches are available which, due to their crystal oscillator
Crystal oscillator
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency...
timing element, are much more accurate than mechanical timepieces. Because they contain a microchip
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
, they often include date and time-of-day functions as well. Some may have a connector for external sensors, allowing the stopwatch to be triggered by external events, thus measuring elapsed time far more accurately than is possible by pressing the buttons with one's finger. The first digital timer used in organized sports was the Digitimer, developed by Cox Electronic Systems, Inc. of Salt Lake City Utah (1971). It utilized a Nixie-tube
Nixie tube
A nixie tube is an electronic device for displaying numerals or other information. The glass tube contains a wire-mesh anode and multiple cathodes. In most tubes, the cathodes are shaped like numerals. Applying power to one cathode surrounds it with an orange glow discharge...
readout and provided a resolution of 1/1000 second. Its first use was in ski racing, but was later used by the World University Games in Moscow, Russia, the U.S. NCAA, and in the Olympic trials.
The device is used when time periods must be measured precisely and with a minimum of complications. Laboratory experiments and sporting events like sprints
Sprint (race)
Sprints are short running events in athletics and track and field. Races over short distances are among the oldest running competitions. The first 13 editions of the Ancient Olympic Games featured only one event—the stadion race, which was a race from one end of the stadium to the other...
are good examples.
The stopwatch function is also present as an additional function of many digital wristwatches, cell phones, portable music players, and computers.
See also
- ChronographChronographA chronograph is a timepiece or watch with both timekeeping and stopwatch functions as well as other functions. Pocket watch chronographs were produced as early as the 18th century but did not become popular until the 1820s...
- Time clockTime clockA time clock, sometimes known as a clock card machine or punch clock or time recorder, is a mechanical timepiece used to assist in tracking the hours an employee of a company worked. In regards to mechanical time clocks this was accomplished by inserting a heavy paper card, called a timesheet,...
- TimekeeperTimekeeperA timekeeper is an instrument or person that measures the passage of time; in the case of the latter, often with the assistance of a clock or stopwatch...
- Time to digital converterTime to digital converterIn electronic instrumentation and signal processing, a time to digital converter is a device for converting a signal of sporadic pulses into a digital representation of their time indices. In other words, a TDC outputs the time of arrival for each incoming pulse...
- TimerTimerA timer is a specialized type of clock. A timer can be used to control the sequence of an event or process. Whereas a stopwatch counts upwards from zero for measuring elapsed time, a timer counts down from a specified time interval, like an hourglass.Timers can be mechanical, electromechanical,...
- The Stopwatch GangThe Stopwatch GangThe Stopwatch Gang consisted of three transplanted Canadians who made a living robbing banks in the United States and Canada—an estimated 100 banks and $15 million CDN. Consisting of Paddy Mitchell, Lionel Wright and Stephen Reid. The gang's greatest heist took place at a Bank of America branch in...