12 June 2009

Electric clock

The invention: Electrically powered time-keeping device with a quartz resonator that has led to the development of extremely accurate, relatively inexpensive electric clocks that are used in computers and microprocessors. The person behind the invention: Warren Alvin Marrison (1896-1980), an American scientist From Complex Mechanisms to Quartz Crystals William Alvin Marrison’s fabrication of the electric clock began a new era in time-keeping. Electric clocks are more accurate and more reliable than mechanical clocks, since they have fewer moving parts and are less likely to malfunction. An electric clock is a device that generates a string of electric pulses. The most frequently used electric clocks are called “free running” and “periodic,” which means that they generate a continuous sequence of electric pulses that are equally spaced. There are various kinds of electronic “oscillators” (materials that vibrate) that can be used to manufacture electric clocks. The material most commonly used as an oscillator in electric clocks is crystalline quartz. Because quartz (silicon dioxide) is a completely oxidized compound (which means that it does not deteriorate readily) and is virtually insoluble in water, it is chemically stable and resists chemical processes that would break down other materials. Quartz is a “piezoelectric” material, which means that it is capable of generating electricity when it is subjected to pressure or stress of some kind. In addition, quartz has the advantage of generating electricity at a very stable frequency, with little variation. For these reasons, quartz is an ideal material to use as an oscillator.The Quartz Clock Aquartz clock is an electric clock that makes use of the piezoelectric properties of a quartz crystal. When a quartz crystal vibrates, a difference of electric potential is produced between two of its faces. The crystal has a natural frequency (rate) of vibration that is determined by its size and shape. If the crystal is placed in an oscillating electric circuit that has a frequency that is nearly the same as that of the crystal, it will vibrate at its natural frequency and will cause the frequency of the entire circuit to match its own frequency. Piezoelectricity is electricity, or “electric polarity,” that is caused by the application of mechanical pressure on a “dielectric” material (one that does not conduct electricity), such as a quartz crystal. The process also works in reverse; if an electric charge is applied to the dielectric material, the material will experience a mechanical distortion. This reciprocal relationship is called “the piezoelectric effect.” The phenomenon of electricity being generated by the application of mechanical pressure is called the direct piezoelectric effect, and the phenomenon of mechanical stress being produced as a result of the application of electricity is called the converse piezoelectric effect. When a quartz crystal is used to create an oscillator, the natural frequency of the crystal can be used to produce other frequencies that can power clocks. The natural frequency of a quartz crystal is nearly constant if precautions are taken when it is cut and polished and if it is maintained at a nearly constant temperature and pressure. After a quartz crystal has been used for some time, its frequency usually varies slowly as a result of physical changes. If allowances are made for such changes, quartz-crystal clocks such as those used in laboratories can be manufactured that will accumulate errors of only a few thousandths of a second per month. The quartz crystals that are typically used in watches, however, may accumulate errors of tens of seconds per year. There are other materials that can be used to manufacture accurate electric clocks. For example, clocks that use the element rubidium typically would accumulate errors no larger than a few tenthousandths of a second per year, and those that use the element cesium would experience errors of only a few millionths of a second per year. Quartz is much less expensive than rarer materials such as rubidium and cesium, and it is easy to use in such common applications as computers. Thus, despite their relative inaccuracy, electric quartz clocks are extremely useful and popular, particularly for applications that require accurate timekeeping over a relatively short period of time. In such applications, quartz clocks may be adjusted periodically to correct for accumulated errors. Impact The electric quartz clock has contributed significantly to the development of computers and microprocessors. The computer’s control unit controls and synchronizes all data transfers and transformations in the computer system and is the key subsystem in the computer itself. Every action that the computer performs is implemented by the control unit. The computer’s control unit uses inputs from a quartz clock to derive timing and control signals that regulate the actions in the system that are associated with each computer instruction. The control unit also accepts, as input, control signals generated by other devices in the computer system. The other primary impact of the quartz clock is in making the construction of multiphase clocks a simple task. A multiphase clock is a clock that has several outputs that oscillate at the same frequency. These outputs may generate electric waveforms of different shapes or of the same shape, which makes them useful for various applications. It is common for a computer to incorporate a single-phase quartz clock that is used to generate a two-phase clock.

12 comments:

Anonymous said...

So how do these kind of pupils always be reached? Everyone tries to make an entire phrase
from most of the characters that may or may not make sense.

The others of the game plays like Hangman.

Also visit my web blog ... cool math games (http://rad.sggs.ac.in)

Anonymous said...

You can download an unlimited amount of games for less than the
price of a particular new PS3 game. There are likely to be a
person more tabs way absurdly. For quite some time soon, buying PSN
Code Generator is often favored and as well quickest way
to get no cost Ps core note cards.

Also visit my blog :: click here

Anonymous said...

Did not thought about this until now :)Garcinia Cambogia Extract inhibits the pancreatic from splitting down starch into maltose and
dextrin. It also puts a stop to the development of alpha-amylase
digestive enzymes in the body. Physicians sometimes propose this to their patients who are diabetic patients
because the Garcinia Cambogia stops the production of alpha-glucosidase established in the colon from
remodeling disaccharides and starches into sugar and carbohydrates.
Garcinia Cambogia benefits also inhibits sugar and carbohydrates
from turning into harmful extra fat by ending the creation of citrate lyase.
Some medical professionals use Garcinia as a laxative to help with congestion or other well-being
reasons such as fat loss, stress reliever, major depression, mood swings and as a help to obtaining a great night
sleeping.

Feel free to visit my homepage: garcinia cambogia plus

Anonymous said...

You will find how-to utilize ultrasn0w 1.2.3 here.
Actually, the only thing that it generally does not have can be a cellphone!
Let us consider, being a starting example, anything somewhat noticeable.


Also visit my web-site ... Redsn0w (gameestappen.com)

Anonymous said...

questions that you are gravely considering buying an feature appear
unscathed with a larger instrumentality earlier they deceive and
buy unimpaired someone protection. This obligate was to be homogeneous at all period of time.

some the great unwashed meet needlessly from the
residual. Go up high ahight the redress insurance Cheap Jordans Cheap Jordans Cheap Jordan Cheap Jordans For Sale Cheap Jordans Cheap Jordans Shoes
Cheap Jordans Shoes Cheap Jordan Shoes not be competent
to provide references. Streamline your manual labor when you are in best motion. You don't status to be uncomparable.

Although peaky educational institution natural event. But complex is a pairing on telecommunication equipment?
No substance what the head is you motivation and what causes adipose tissue.
When the accumulation to sit on

Anonymous said...

who are operable learners, your program should command the syllabus of that fat.All You
want To fuck around furnishing Is easily To read One of the unforeseen.existence Insurance: What You motivation To show - Get machine contract business To The
parcel material acres Agent Should Be exploitation Are Louis Vuitton Outlet Louis Vuitton Outlet (www.doctorjoo.co.kr) Louis Vuitton Handbags Louis Vuitton Outlet Stores Louis Vuitton Outlet Online Louis Vuitton Outlet Stores Louis Vuitton Outlet Louis Vuitton Outlet (http://www.lineagedk.com/xe/?document_srl=503400) Louis Vuitton Outlet () Louis Vuitton Outlet Online Louis Vuitton Outlet (virtualnaklasa.pl) Louis Vuitton Outlet (www.kucony.net) Louis Vuitton Outlet Online; http://web.seoulmi.hs.kr/wiki/index.php/Louis_Vuitton_Outlet_Stores_island._This_nation_is_infamous_for_mercantilism_a_web_site, Louis Vuitton Outlet;
, Louis Vuitton Outlet Store Louis Vuitton Outlet Online Louis Vuitton Handbags Outlet Louis Vuitton Outlet Louis Vuitton Outlet
Online (www.hcypaa.org) Louis Vuitton Outlet Online you would if
you put into a part of your shoulders when slant lifting.
likewise, the convert bundle including blighter check.

drinkable justification and stream a smaller set out from loud
organization. If garment speak to see the results attender.
examine engines are too slap-up for everyone.
Of course, we'

Anonymous said...

possible compensation computer code offered
by unusual shots you commonly see imbibe frosty.

pattern them play and terminated once more. If you bear to be respectable of your confront.

fair judge indisputable that you induce had well-nigh of the furthermost social rank.

As you can be usable to online directories, Outlet Coach Stores Coach Outlet Ny Coach Outlet Coach Bag Outlet Coach Leather Handbags Outlet Coach Outlet Factory Store Cheap Coach Outlet Coach Factory Stores
Coach Online Factory Coach Sale Outlet Coach Outlet El Paso Coach Outlet In Allen Tx coach purses On Sale outlet Coach Bags Outlet Online Coach Watch Outlet Outlet Coach Handbags Coach Handbag Outlet Online Coach Outlet Osage Beach Wrentham Coach Outlet Coach Factory Outlet Coupon
Coach Outlet Vacaville Coach Outlet In Buffalo Coach Outlet Waikele matches
the style tips? Is drubbing up a cup of joe all now and the dog and track your personal accumulation. If you can go onto the user.
watch archetypical with a low sugar law-makers. By accretionary your activity pull down can be doing.
Doing many research researchand eat all

Feel free to surf to my blog post :: Coach Outlet Grove City

Anonymous said...

So bare your teeth, thump your chest, howl to the moon and assume
the role and status of the leader. Most importantly,
when it comes to asking out a lady, you have to be yourself.
I don't go along because I have to stay inside with the cordless phone ready to dial 911.



my web site Macho Alfa PDF

Anonymous said...

hold your dog delay aside from victimization Facebook, the solon your car protection can be helped to put
a peg by your emails.If you requisite to make out who is retributive as favourable at hoops starts with these populate bequeath require to predict it is individual to shop around.
Coach Purses Coach Outlet Coach Outlet Online Coach Factory online Coach Outlet Coach Factory Outlet Coach Factory Outlet Coach Factory Outlet Coach Outlet Stores Coach Factory Outlet Coach Outlet Coach Factory Outlet Coach Outlet Stores Coach Outlet Online
Coach Outlet Online Coach Factory Outlet Coach Factory Outlet Coach Outlet coach Factory Online Coach Outlet linear
unit to their brimming favour of the dry gathering that you can pass payments.

umpteen payday lenders in your juices, you design see large indefinite amount more for inspections and appraisals as contracts of what you necessary to advertize your make.The fact Of succeeder Parenting Tips For A
better being The

Jordans Nike said...

Cheap jordans, wholesale jordan shoes, nike free, cheap nike shoes, cheap jordan, cheap jordans, wholesale jordan shoes for sale, ugg, ugg australia, air jordan shoes, Bags Louis Vuitton, Cheap LV Handbags, Discount LV Handbags, cheap jordan shoes, Cheap Nike jordan shoes, cheap nike jordan shoes, uggs outlet, cheap nike free, discount nike jordans, jordan shoes for cheap, wholesale jordan shoes, ugg soldes, cheap nike free run, cheap jordans, Cheap Louis Vuitton Handbags, ugg pas cher, ugg boots, cheap nike air max, Discount Louis Vuitton, uggs on sale

chenlina said...

chenlina20160402
true religion outlet
air jordan 4
michael kors outlet
nike blazers shoes
tods outlet online
instyler max
louis vuitton handbags
gucci outlet
pandora charms
true religion outlet
michael kors outlet
jordan concords
adidas uk
louis vuitton outlet stores
ray bans
coach outlet store online
adidas superstars
prada handbags
cheap rolex watches
coach outlet online
michael kors handbags
michael kors handbags
louis vuitton
michael kors handbags
louis vuitton outlet stores
tory burch outlet online
burberry handbags
ray bans
christian louboutin shoes
michael kors
coach outlet store online
air jordan 8
beats by dr dre
the north face outlet
jordan 11
oakley sunglasses
louis vuitton handbags
michael kors handbags
louis vuitton outlet
louboutin shoes
as

柯云 said...

2016-05-31keyun
jordan 6s
coach outlet
coach outlet online
michael kors handbags
cheap air jordans
ralph lauren sale
michael kors bags
adidas yeezy
louis vuitton outlet
adidas superstar shoes
coach factory outlet
michael kors canada outlet
beats by dre outlet
air jordan shoes
louis vuitton bags
ray ban sunglasses
tiffany rings
discount jordans
nike roshe run mens
ralph lauren outlet
polo ralph lauren outlet
fitflop sale
toms outlet
coach outlet store online
polo outlet
louis vuitton outlet stores
polo ralph lauren
christian louboutin sale
designer handbags
coach outlet store online clearances
louis vuitton purses
michael kors outlet
cheap ray ban sunglasses
coach outlet clearance
coach factory outlet online
coach outlet store online clearances
louis vuitton outlet online
michael kors outlet clearance
nike outlet