Enclosure or inclosure is the process which was used in order to end some traditional rights, such as mowing meadows for hay, or grazing livestock on land which is owned by another person, or a group of people. In England and Wales the term is also used for the process that ended the ancient system of arable farming in open fields SONY VAIO VGN-FW21E Battery .
Under enclosure, such land is fenced (enclosed) and deededor entitled to one or more owners. By the 19th century, unenclosed commons had become largely restricted to rough pasture in mountainous areas and in relatively small parts of the lowlands Asus M52N Battery .
"Enclosure" is the modern spelling, while "inclosure" is a much older spelling still used in the United Kingdom in legal documents and place names.
The process of enclosure has sometimes been accompanied by force Dell Latitude E6400 ATG Battery ,
resistance, and bloodshed, and remains among the most controversial areas of agricultural and economic history in England.Marxist and neo-Marxist historians argue that rich landowners used their control of state processes to appropriate public land for their private benefit SONY VAIO VGN-FW21J Battery .
This created a landless working class that provided the labour required in the new industries developing in the north of England. For example: "In agriculture the years between 1760 and 1820 are the years of wholesale enclosure in which, in village after village, common rights are lost" SONY VAIO VGN-FW21L Battery .
"Enclosure (when all the sophistications are allowed for) was a plain enough case of class robbery".
W A Armstrong argued that this is perhaps an oversimplification, that the better-off members of the European peasantry encouraged and participated actively in enclosure, seeking to end the perpetual poverty of subsistence farming SONY VAIO VGN-FW21M Battery.
"We should be careful not to ascribe to (enclosure) developments that were the consequence of a much broader and more complex process of historical change". "... he impact of eighteenth and nineteenth century enclosure has been grossly exaggerated " SONY VAIO VGN-FW21Z Battery .
A wide variety of opinions are quoted, with references, in the online Oxford University Press article.
Enclosure of manorial waste was authorised by the Statute of Merton (1235) and the Statute of Westminster (1285) SONY VAIO VGN-FW25T/B Battery .
Throughout the medieval and modern periods, piecemeal enclosure took place in which adjacent strips were fenced off from the common field. This was sometimes undertaken by small landowners, but more often by large landowners and lords of the manor. Significant enclosures (or emparkments) took place to establish deer parks SONY VAIO VGN-FW26T/B Battery .
Some (but not all) of these enclosures took place with local agreement.
There was a significant rise in enclosure during the Tudor period Dell Latitude E6400 battery,10400mAh,11.1V .
These enclosures largely resulted in conversion of land use from arable to pasture – usually sheep farming. These enclosures were often undertaken unilaterally by the landowner. Enclosures during the Tudor period were often accompanied by a loss of common rights and could result in the destruction of whole villages Dell Latitude E6400 battery,10400mAh,11.1V .
Open farmland in England had been commonly enclosed as pastureland for sheep from the fourteenth to the sixteenth century as populations declined. Foreign demand for English wool also helped encourage increased production, and the wool industry was often thought to be more profitable for landowners who had large decaying farmlands Dell Latitude E6500 battery,10400mAh,11.1V .
Some manorial lands lay in disrepair from a lack of tenants, which made them undesirable to both prospective tenants and landowners who could be fined and ordered to make repairs. Enclosure and sheep herding (which required very few labourers) were a solution to the problem SONY VAIO VGN-FW27/B Battery ,
but of course this created other problems: unemployment, the displacement of impoverished rural labourers, and decreased domestic grain production which made England more susceptible to famine and higher prices for domestic and foreign grain SONY VAIO VGN-FW27/W Battery .
From as early as the 12th century, some open fields in Britain were being enclosed into individually owned fields. InGreat Britain, the process sped up during the 15th and 16th centuries as sheep farming grew more profitable. In the 16th and early 17th centuries, the practice of enclosure was denounced by theChurch and the government SONY VAIO VGN-FW31ZJ Battery ,
particularly depopulating enclosure, and legislation was drawn up against it. But elite opinion began to turn towards support for enclosure, and rate of enclosure increased in the seventeenth century. This led to a series of government acts addressing individual regions, which were given a common framework in the Inclosure Consolidation Act of 1801 SONY VAIO VGN-FW27T/H Battery .
Sir Thomas More, in his 1516 work Utopia suggests that the practice of enclosure is responsible for some of the social problems affecting England at the time, specifically theft.
But I do not think that this necessity of stealing arises only from hence SONY VAIO VGN-FW29/B Battery ;
there is another cause of it, more peculiar to England.' 'What is that?' said the Cardinal: 'The increase of pasture,' said I, 'by which your sheep, which are naturally mild, and easily kept in order, may be said now to devour men and unpeople, not only villages, but townsSONY VAIO VGN-FW290JRB Battery ;
for wherever it is found that the sheep of any soil yield a softer and richer wool than ordinary, there the nobility and gentry, and even those holy men, the abbots not contented with the old rents which their farms yielded, nor thinking it enough that they, living at their ease, do no good to the public, resolve to do it hurt instead of good SONY VAIO VGN-FW290JTB Battery .
They stop the course of agriculture, destroying houses and towns, reserving only the churches, and enclose grounds that they may lodge their sheep in them.
The loss of agricultural labour also hurt others like millers whose livelihood relied on agricultural produce SONY VAIO VGN-FW290JTH Battery .
Fynes Moryson reported on these problems in An Itinerary (1617):
England abounds with corn [wheat and other grains], which they may transport, when a quarter (in some places containing six, in others eight bushels) is sold for twenty shillings, or under SONY VAIO VGN-FW33G/E1 Battery ;
and this corn not only serves England, but also served the English army in the civil wars of Ireland, at which time they also exported great quantity thereof into foreign parts, and by God's mercy England scarce once in ten years needs a supply of foreign corn, which want commonly proceeds of the covetousness of private men, exporting or hiding it SONY VAIO VGN-FW33G/W Battery .
Yet I must confess, that daily this plenty of corn decreaseth, by reason that private men, finding greater commodity in feeding of sheep and cattle than in the plow, requiring the hands of many servants, can by no law be restrained from turning cornfields into enclosed pastures, especially since great men are the first to break these laws SONY VAIO VGN-FW33GW Battery .
By some accounts, 3/4ths to 9/10ths of the tenant farmers on some estates were evicted in the late medieval period. Other economic historians argue that forced evictions were probably rare. Landlords would turn to enclosure as an option when lands went unused (Dell XPS M1210 Battery) http://www.hdd-shop.co.uk .
The enclosure of common land for sheep farming and the consequent eviction of villagers from their homes and their livelihoods became an important political issue for the Tudors Dell Studio XPS 1640 Battery .
Reflecting royal opposition to this practice, the anti-enclosure acts of 1489 and 1516 were aimed at stopping the waste of structures and farmland, which would lead to lower tax revenues, fewer potential military conscripts for the crown, and more potential underclass rebels Dell Vostro 1710 Battery .
The Tudor authorities were extremely nervous about how the villagers who had lost their homes would react. In the sixteenth century, lack of income made one a pauper. If one lost one's home as well, one became a vagrant; and vagrants were regarded (and treated) as criminals Dell KM958 battery .
The authorities saw many people becoming what they regarded as vagabonds and thieves as a result of enclosure and depopulation of villages. From the time of Henry VII onwards, Parliament began passing Acts to stop enclosure, to limit its effects, or at least to fine those responsible Dell Studio 1555 battery .
The first such law was in 1489. Over the next 150 years, there were 11 more Acts of Parliament and eight commissions of enquiry on the subject.
Initially, enclosure was not itself an offence, but where it was accompanied by the destruction of houses Sony VGP-BPS13 battery ,
half the profits would go to the Crown until the lost houses were rebuilt. (The 1489 Act gave half the profits to the superior landlord, who might not be the Crown, but an Act of 1536 allowed the Crown to receive this half share if the superior landlord had not taken action.) Sony VGP-BPS13/B battery
In 1515, conversion from arable to pasture became an offence. Once again, half the profits from conversion would go to the Crown until the arable land was restored. Neither the 1515 Act nor the previous laws were effective in stopping enclosure Sony VGP-BPS13/S battery ,
so in 1517 Cardinal Wolsey established a commission of enquiry to determine where offences had taken place – and to ensure the Crown received its half of the profits.
Inflation and enclosure
Alongside population growth, inflation was a major reason for enclosure Sony VGP-BPS13A/B battery .
When Henry VIII became King in 1509, the royal finances were in good shape thanks to the prudence of his father Henry VII. But this soon changed as Henry VIII doubled household expenditure and started costly wars against both France and Scotland Sony VGP-BPS13B/B battery .
With his wealth rapidly decreasing, Henry VIII imposed a series of taxes devised by his finance minister, Thomas Wolsey. Soon the people began to resent Wolsey's taxes and a new source of finance had to be found: in 1544, Henry reduced the silver content of new coins by about 50%; this was repeated to a lesser extent the following year Sony VGP-BPL9 battery .
This, combined with injection of bullion from the New World, increased the money supply in England; which led to continuing price inflation. This threatened landowners' wealth, which encouraged the landowners to become more efficient, and enclosure was seen as a way of doing this Sony VGP-BPS13B/B battery .
The debasement of the coinage was not seen as a cause of inflation (and therefore enclosures) until the Duke of Somerset was Protector of Edward VI. Until then enclosures were seen as the cause of inflation, not the outcome. When Thomas Smith advised Somerset that enclosure was a resulit of inflation, he was only ignored Sony VGP-BPL15 battery .
It was not until John Dudley, 1st Duke of Northumberland was Protector that his finance minister William Cecil took action on debasement to try to stop enclosure.
After 1529 or so, the problem of untended farmland disappeared with the rising population Dell Inspiron E1505 battery .
There was a desire for more arable land along with much antagonism toward the tenant-graziers with their flocks and herds. Increased demand along with a scarcity of tillable land caused rents to rise dramatically in the 1520s to mid-century Dell Latitude E6400 battery .
The 1520s appear to have been the point at which the rent increases became extreme, with complaints of rack-rent appearing in popular literature, such as the works of Robert Crowley. There were popular efforts to remove old enclosures, and much legislation of the 1530s and 1540s concerns this shift HP Pavilion dv6000 Battery .
Angry tenants impatient to reclaim pastures for tillage were illegally destroying enclosures. Beginning with Kett's Rebellion in 1549, agrarian revolts swept all over the nation, and other revolts occurred periodically throughout the century HP Pavilion dv8000 battery .
Clearly the popular rural mentality was rather medieval, the goal being to try to restore the security, stability, and functionality of the old order. However, in looking to the past HP PAVILION DV6000 Battery, 8800mAh, 10.8V ,
early modern commoners believed they were asserting ancient traditional and constitutional rights granted to the free and sturdy English yeoman as opposed to the enslaved and effeminate French — a contrast often drawn by 16th century writers, such as [First Name Omitted] Hutchins HP PAVILION DV8000 Battery, 8800mAh, 10.8V .
This emphasis on rights was to have a pivotal role in the modern era unfolding from the Enlightenment. D. C. Coleman writes that the English commons were disturbed by the loss of common rights under enclosure which might involve the right "to cut underwood, to run pigs" (40) SONY VAIO VGN-FZ Battery .
The Midland Revolt
In 1607, beginning on May Eve in Haselbech, Northamptonshire and spreading to Warwickshire and Leicestershire throughout May, riots took place as a protest against the enclosure of common land HP Pavilion DV6000 battery - 8800mAh .
Known as The Midland Revolt, it drew considerable support and was led by John Reynolds, otherwise known as "Captain Pouch", a tinker said to be from Desborough, Northamptonshire HP Pavilion DV8000 battery - 7800mAh .
He told the protestors he had authority from the King and the Lord of Heaven to destroy enclosures and promised to protect protesters by the contents of his pouch, carried by his side, which he said would keep them from all harm. (After he was captured, his pouch was opened - all that was in it was a piece of green cheese.) HP Pavilion DV6000 battery - 8800mAh
Thousands of people were recorded at Hillmorton, Warwickshire and at Cotesbach, Leicestershire. A curfew was imposed in the city of Leicester, as it was feared citizens would stream out of the city to join the riots. A gibbet was erected in Leicester as a warning, and was pulled down by the citizens HP Pavilion DV8000 battery - 6600mAh .
Newton Rebellion: 8 June 1607
The Newton Rebellion was one of the last times that the peasantry of England and the gentry were in open armed conflict. Things had come to a head in early June SONY VAIO VGN-FZ18 Battery .
James I issued a Proclamation and ordered his Deputy Lieutenants in Northamptonshire to put down the riots. It is recorded that women and children were part of the protest. Over a thousand had gathered at Newton, near Kettering, pulling down hedges and filling ditches, to protest against the enclosures of Thomas Tresham SONY VAIO VGN-FZ21E Battery .
The Treshams were unpopular for their voracious enclosing of land - both the family at Newton and their more well-known Roman Catholic cousins at nearby Rushton, the family of Francis Tresham, who had been involved two years earlier in the Gunpowder Plot and had apparently died in The Tower SONY VAIO VGN-FW31J Battery - 5200mAh/7800mAh/10400mAh, 11.10V .
Sir Thomas Tresham of Rushton was known as "the most odious man in the county". The old Roman Catholic gentry family of the Treshams had long argued with the emerging Puritan gentry family, the Montagus of Boughton, about territory SONY VAIO VGN-FW31J Battery - 5200mAh/7800mAh/10400mAh, 11.10V .
Now Tresham of Newton was enclosing common land - The Brand - that had been part of Rockingham Forest.
Edward Montagu, one of the Deputy Lieutenants, had stood up against enclosure in Parliament some years earlier, but was now placed by the King in the position effectively of defending the Treshams Dell Latitude E6400 battery,10400mAh/7800mAh .
The local armed bands and militia refused the call-up, so the landowners were forced to use their own servants to suppress the rioters on 8 June 1607. The Royal Proclamation was read twice. The rioters continued in their actions, although at the second reading some ran away Dell Latitude E6400 Battery,10400mAh/7800mAh .
The gentry and their forces charged. A pitched battle ensued. 40-50 were killed and the ringleaders were hanged and quartered.
A memorial stone to those killed now stands at the former church of St Faith, Newton, Northamptonshire Dell Latitude E6400 Battery,10400mAh/7800mAh .
The Tresham family declined soon after 1607. The Montagu family went on through marriage to become the Dukes of Buccleuch, one of the largest landowners in Britain.
Parliamentary Enclosure and open fields Dell Latitude E6400 Battery,10400mAh/7800mAh
During the 18th and 19th centuries, enclosures were by means of local acts of Parliament, called the Inclosure Acts. These "parliamentary" enclosures consolidated strips in the open fields into more compact units, and enclosed much of the remaining pasture commons or wastes Dell Latitude E6500 battery,10400mAh/7800mAh .
Parliamentary enclosures usually provided commoners with some other land in compensation for the loss of common rights, although often of poor quality and limited extent Dell Latitude E6500 battery,10400mAh/7800mAh .
Parliamentary enclosure was also used for the division and privatisation of common wastes (in the original sense of "uninhabited places"), such as fens, marshes, heathland, downland, moors Dell Latitude E6500 battery,10400mAh/7800mAh .
Marxist historians have focussed on enclosure as a part of the class conflict that eventually eliminated the English peasantry and saw the emergence of the bourgeoisie. From this viewpoint, theEnglish Civil War provided the basis for a major acceleration of enclosures Dell Latitude E6500 battery,10400mAh/7800mAh .
The parliamentary leaders supported the rights of landlords vis-a-vis the King, whose Star Chamber court, abolished in 1641, had provided the primary legal brake on the enclosure process. By dealing an ultimately crippling blow to the monarchy HP Pavilion DV6-1210SA battery - 5200mAh/8800mAh
(which, even after the Restoration, no longer posed a significant challenge to enclosures) the Civil War paved the way for the eventual rise to power in the 18th century of what has been called a "committee of Landlords", a prelude to the UK's parliamentary system. The economics of enclosures also changed HP Pavilion DV7 battery - 7200mAh .
Whereas earlier land had been enclosed in order to make it available for sheep farming, by 1650 the steep rise in wool prices had come to an end. Thereafter, the focus shifted to implementation of new agricultural techniques, including fertilizer, new crops, and crop rotation Ibm THINKPAD X200 Battery 8800mAh, 11.1V Replacement
, all of which greatly increased the profitability of large-scale farms . The enclosure movement probably peaked from 1760 to 1832; by the latter date it had essentially completed the destruction of the medieval peasant community Ibm THINKPAD X200 Battery 8800mAh, 11.1V Replacement .
Before enclosure, much of the arable land in the central region of England was organised into an open field system. Enclosure was not simply the fencing of existing holdings, but led to fundamental changes in agricultural practice Ibm THINKPAD X200 Battery 8800mAh, 11.1V Replacement .
Scattered holdings of strips in the common field were consolidated to create individual farms that could be managed independently of other holdings. Prior to enclosure, rights to use the land were shared between land owners and villagers (commoners) SONY VAIO VGN-FW21E Battery .
For example, commoners would have the right (common right) to graze their livestock when crops or hay were not being grown, and on common pasture land. The land in a manor under this system would consist of SONY VAIO VGN-NR11S/S Battery
- Two or three very large common arable fields
- Several very large common haymeadows
- Closes, small areas of enclosed private land such as paddocks, orchards or gardens, mostly near houses SONY VAIO VGN-NR11M/S Battery
- In some cases, a park around the principal house, the manor house
- Common waste – rough pasture land (effectively everything not in the previous categories) SONY VAIO VGN-NR11Z/S Battery
Note that at this time "field" meant only the unenclosed and open arable land – most of what would now be called "fields" would then have been called "closes". The only boundaries would be those separating the various types of land, and around the closes SONY VAIO VGN-NR11Z/T Battery .
In each of the two waves of enclosure, two different processes were used. One was the division of the large open fields and meadows into privately controlled plots of land, usually hedged and known at the time as severals. In the course of enclosure, the large fields and meadows were divided and common access restricted Sony VAIO VGN-FZ21E Battery .
Most open-field manors in England were enclosed in this manner, with the notable exception of Laxton, Nottinghamshire and parts of the Isle of Axholme in North Lincolnshire.
The history of enclosure in England is different from region to region Sony VAIO VGN-FW21E Battery .
Not all areas of England had open-field farming in the medieval period. Parts of south-east England (notably parts of Essex andKent) retained a pre-Roman system of farming in small enclosed fields. Similarly in much of west and north-west England, fields were either never open, or were enclosed early Sony VAIO VGN-NR11S/S Battery .
The primary area of open field management was in the lowland areas of England in a broad band from Yorkshire and Lincolnshire diagonally across England to the south, taking in parts of Norfolk and Suffolk, Cambridgeshire, large areas of the Midlands, and most of south central England Sony VAIO VGN-NR11Z/S Battery .
These areas were most affected by the first type of enclosure, particularly in the more densely-settled areas where grazing was scarce and farmers relied on open field grazing after the harvest and on the fallow to support their animals Sony VAIO VGN-NR11Z/T Battery .
The second form of enclosure affected those areas, such as the north, the far south-west, and some other regions such as the East Anglian Fens, and the Weald, where grazing had been plentiful on otherwise marginal lands, such as marshes and moors Sony VAIO VGN-NR11M/S Battery .
Access to these common resources had been an essential part of the economic life in these strongly pastoral regions, and in the Fens, large riots broke out in the seventeenth century, when attempts to drain the peat and silt marshes were combined with proposals to partially enclose them SONY VAIO VGN-FZ180E Battery .
Both economic and social factors drove the enclosure movement. In particular, the demand for land in the seventeenth century, increasing regional specialisation, engrossment in landholding and a shift in beliefs regarding the importance of "common wealth" (usually implying common livelihoods) SONY VAIO VGN-FZ220E Battery
as opposed to the "public good" (the wealth of the nation or the GDP) all laid the groundwork for a shift of support among elites to favour enclosure. Enclosures were conducted by agreement among the landholders (not necessarily the tenants) throughout the seventeenth century SONY VAIO VGN-FZ340E Battery ;
enclosure by Parliamentary Act began in the eighteenth century. Enclosed lands normally could demand higher rents than unenclosed, and thus landlords had an economic stake in enclosure, even if they did not intend to farm the land directly SONY VAIO VGN-FZ430E Battery .
While many villagers received plots in the newly enclosed manor, for small landholders this compensation was not always enough to offset the costs of enclosure and fencing. Many historians believe that enclosure was an important factor in the reduction of small landholders in England SONY VAIO VGN-FZ460E Battery ,
as compared to the Continent, though others believe that this process had already begun from the seventeenth and eighteenth centuries. Enclosure faced a great deal of popular resistance because of its effects on the household economies of smallholders and landless labourers SONY VAIO VGN-FZ480E Battery .
Common rights had included not just the right of cattle or sheep grazing, but also the grazing of geese, foraging for pigs, gleaning, berrying, and fuel gathering. During the period of parliamentary enclosure, employment in agriculture did not fall, but failed to keep pace with the growing population SONY VAIO VGN-FZ4000 Battery .
Consequently large numbers of people left rural areas to move into the cities where they became labourers in the Industrial Revolution.
By the end of the 19th century the process of enclosure was largely complete, in most areas just leaving a few pasture commons and village greens SONY VAIO VGN-FZ31E Battery .
Many landowners became rich through the enclosure of the commons, while many ordinary folk had a centuries-old right taken away. Land enclosure has been condemned as a gigantic swindle on the part of large landowners, and Oliver Goldsmith wrote "The Deserted Village" in 1770 deploring rural depopulation SONY VAIO VGN-FZ31B Battery .
An anonymous protest poem from the 17th century summed up the anti-enclosure feeling:
They hang the man, and flog the woman,
That steals the goose from off the common SONY VAIO VGN-FZ31J Battery ;
But let the greater villain loose,
That steals the common from the goose.
"Stop to consider how the so-called owners of the land got hold of it SONY VAIO VGN-FZ31M Battery .
They simply seized it by force, afterwards hiring lawyers to provide them with title-deeds. In the case of the enclosure of the common lands, which was going on from about 1600 to 1850, the land-grabbers did not even have the excuse of being foreign conquerorsSONY VAIO VGN-FZ31Z Battery ;
they were quite frankly taking the heritage of their own countrymen, upon no sort of pretext except that they had the power to do so.
– George Orwell."
Wire wrap is a technology used to assemble electronics SONY VAIO VGN-FZ38M Battery .
It is a method to construct circuit boards without having to make a printed circuit board. Wires can be wrapped by hand or by machine, and can be hand-modified afterwards. It was popular for large-scale manufacturing in the 60s and early 70s, and continues to be used for short runs and prototypes SONY VGP-BPS8 Battery .
It is unusual among prototyping technologies in that very complex assemblies can be produced by automated equipment, and then easily repaired or modified by hand.
Wire wrap construction can produce assemblies which are more reliable than printed circuits SONY VGP-BPS13/S Battery
— connections are less prone to fail due to vibration or physical stresses on the base board, and the lack of solder precludes soldering faults such as corrosion, cold joints and dry joints. The connections themselves are firmer and have lower electrical resistance due to cold welding of the wire to the terminal post at the corners SONY VGP-BPS13A/B Battery .
A correctly made wire-wrap connection is seven (7) turns of wire with 1.5 turns of insulated wire at the bottom for strain relief. The square hard-gold-plated post thus forms 28 redundant contacts. The silver-plated wire coating cold-welds to the gold SONY VGP-BPS13B/B Battery .
If corrosion occurs, it occurs on the outside of the wire, not on the gas-tight contact, because gold is more noble than silver. A correctly designed wire-wrap tool applies up to twenty tons of force per square inch on each joint SONY VGP-BPS13A/S Battery .
Wire wrap was used for assembly of high frequency prototypes and small production runs, including gigahertz microwave circuits and super computers. It is unique among automated prototyping techniques in that wire lengths can be exactly controlled, and twisted pairs or magnetically-shielded twisted quads can be routed together SONY VGP-BPS13AS Battery .
Wire wrap construction became popular around 1960 in circuit board manufacturing, and use has now sharply declined. Surface-mount technology has made the technique much less useful than in previous decades. Solderless breadboards and the decreasing cost of professionally made PCBs have nearly eliminated this technology Dell Inspiron 1320n Battery .
In telecommunications wire wrap is in common high volume use in modern communications networks for cross connects between copper wiring plant. For example, most phone lines from the outside plant go to wire wrap panels in a central office, whether used for POTS phone service, DSL or T1 lines Dell Inspiron 1464 Battery .
Typically at a main distribution frame Internal Cross Facilities Assignments and External Cross Facilities Assignments, are connected together via jumpers that are wire wrapped. Wire wrap is popular in telecommunications since it is one of the most secure ways to attach wires, and provides excellent and consistent data layer contact Dell Inspiron 1564 Battery .
Wirewrap panels are rated for high quality data services, including Category 5 grade wiring. The principal competitor in this application is punch blocks, which are quicker but less secure Dell Inspiron 1764 Battery .
The electronic parts sometimes plug into sockets. The sockets are attached with cyanoacrylate (or silicone adhesive) to thin plates of glass-fiber-reinforcedepoxy (fiberglass) Dell Studio 1450 Battery .
The sockets have square posts. The usual posts are 0.025 inches (635 micrometres) square, 1 inch (25.4 mm) high, and spaced at 0.1 inch (2.54 mm) intervals. Premium posts are hard-drawn beryllium-copper alloy plated with a 0.000025 inches (25 microinches) (635 nanometres) of gold to prevent corrosion Dell Studio 1457 Battery .
Less-expensive posts are bronze with tin plating.
The two holes at the end of a manual wire wrap tool. The wire goes in the one near the edge, and the post is inserted into the hole in the center Dell Latitude D610 Battery .
30 gauge silver-plated soft copper wire is insulated with a fluorocarbon that does not emit dangerous gases when heated. The most common insulation is "kynar".
The 30 AWG Kynar is cut into standard lengths, then one inch of insulation is removed on each end Toshiba NB100 Battery .
A "wire wrap tool" has two holes. The wire and one quarter inch (6.35 mm) of insulated wire are placed in a hole near the edge of the tool. The hole in the center of the tool is placed over the post .
The tool is rapidly twisted Toshiba Satellite M65 battery .
The result is that 1.5 to 2 turns of insulated wire are wrapped around the post, and atop that, 7 to 9 turns of bare wire are wrapped around the post. The post has room for three such connections, although usually only one or two are needed. This permits manual wire-wrapping to be used for repairs Toshiba Satellite M60 battery .
The turn and a half of insulated wire helps prevent wire fatigue where it meets the post.
Above the turn of insulated wire, the bare wire wraps around the post. The corners of the post bite in with pressures of tons per square inch (MPa) Dell Latitude D830 Battery .
This forces all the gases out of the area between the wire's silver plate and the post's gold or tin corners. Further, with 28 such connections (seven turns on a four-cornered post), a very reliable connection exists between the wire and the post. Furthermore, the corners of the posts are quite "sharp" Dell Latitude D620 Battery .
There are three ways of placing wires on a board.
In professionally-built wire-wrap boards, long wires are placed first so that shorter wires mechanically secure the long wires. Also, to make an assembly more repairable, wires are applied in layers Dell Inspiron Mini 10 Battery .
The ends of each wire are always at the same height on the post, so that at most three wires need to be replaced to replace a wire. Also, to make the layers easier to see, they are made with different colors of insulation. In space-rated or airworthy wire-wrap assemblies Sony VGN-FW11S Battery ,
the wires are boxed, and may be conformally-coated with wax to reduce vibration. Epoxy is never used for the coating because it makes an assembly unrepairable.
Manual Wire Wrap
A manual wire wrap tool resembles a small pen. It is convenient for minor repairs Sony VGN-FW11M Battery .
Wire wrap is one of the most repairable systems for assembling electronics. Posts can be rewrapped up to ten times without appreciable wear, provided that new wire is used each time. Slightly larger jobs are done with a manual "wire wrap gun" having a geared and spring loaded squeeze grip to spin the bit rapidly Sony VGN-FW139E/H battery .
Such tools were used in large numbers in American telephone exchanges in the last third of the 20th century, usually with a bigger bit to handle 22 or 24 AWG wire rather than the smaller 28 or 30 AWG used in circuit boards and backplanes. The larger posts can be rewrapped hundreds of times Dell Latitude E5400 Battery .
They persisted into the 21st century in distribution frames where insulation-displacement connectors had not taken over entirely. Larger, hand held, high speed electric wrap guns replaced soldering in the late 1960s for permanent wiring, when installing exchange equipment. In the middle 1980s they were gradually replaced by connectorized cables Dell Latitude E4200 Battery .
The Apollo Guidance Computer with its short production run and stringent reliability requirement was one of the early applications of wire wrap to computer assembly.
Semiautomated Wire Wrap Dell Inspiron 300M Battery
Semiautomated powered wire-wrap systems place "wire-wrap guns" on arms moved in two dimensions by computer-controlled motors. The guns are manually pulled down, and the trigger pressed to make a wrap. The wires are inserted into the gun manuallyDell Vostro A840 Battery .
This system allows the operator to place wires without concern about whether they are on the correct pin, since the computer places the gun correctly.
Semi-automated wire wrapping is unique among prototyping systems because it can place twisted pairs, and twisted magnetically-shielded quads, permitting the assembly of complex radar and high speed digital circuits Dell Studio 1737 battery .
Automated Wire Wrapping
Automated wire-wrap machines, as manufactured by the Gardner Denver Company in the 1960s and 1970s, were capable of automatically routing, cutting, stripping and wrapping wires onto an electronic "backplane" or "circuit board" Dell Inspiron E1505 battery .
The machines were driven by wiring instructions encoded onto punched cards,Mylar punched hole tape, and early micro computers.
The earliest machines (14FB and 14FG models, for example) were initially configured as "horizontal", which meant that the wire wrap board was placed upside down (pins up) onto a horizontal tooling plate Dell RM791 battery ,
which was then rolled into the machine and locked onto a rotating (TRP table rotational position of four positions) and shifting (PLP = pallet longitudinal position of 11 positions) pallet assembly. These machines included very large hydraulic units for powering the servos that drove the ball screw mounted "A" and "B" drive carriages Dell XPS M1530 battery ,
a 6' tall electronics cabinet loaded with hundreds of IBM control relays, many dozens of solenoids for controlling the various pneumatic mechanical subsystems, and an IBM 029 card reader for positioning instructions. The automatic wire wrap machines themselves were quite large, 6 ft (2 m) tall and 8 ft (3 m) square Dell XPS M2010 battery .
Servicing the machines was extremely complex, and often meant climbing inside them just to work on them. This could be quite dangerous if safety interlocks were not maintained properly; there were rumors throughout the industry that some fatalities/serious injuries had actually occurred Toshiba Satellite P10 Battery .
Later, somewhat smaller machines were "vertical" (14FV) which meant the boards were placed onto a tooling plate with pins facing the machine operator. Gone were the hydraulic units, in favor of direct drive motors to rotate the ball screws, with rotary encoders to provide positioning feedback Acer Aspire One battery 10400mAh .
This generally provided better visibility of the product for the operator, although maximum wrap area was significantly less than the Horizontal machines. Top speeds on horizontal machines were generally around 500-600 wires per hour, while the vertical machines could reach rates as high as 1200 per hour, depending on board quality and wiring configurations SONY VGN-FZ210CE Battery .
Wires would be routed over the board, using "dressing fingers", and carriages would lower the A and B wrapping bits onto the board. The process for wrapping a wire was as follows (Note: the "A" carriage was on the right, while the "B" carriage was on the left) Dell Precision M70 Battery .
Machine carriages would meet at the next "A" carriage X/Y wire routing position, and the wire feed and stripper assembly located just under the "A" carriage would clamp the supply wire and feed it (push) to the "B" carriage. The "B Gripper" on the B carriage would accept the wire by clamping it Toshiba Satellite L305 Battery ,
once limit switches in the strip and feed assembly indicated they had completed the feed cycle. Next, the "B" carriage would move "X" (to the left) to the first wire routing position, pulling the supply wire as it moved through the feed assembly from the supply reel, and the "B" dressing finger would pivot down over the wire Toshiba Satellite T4900 Battery .
Once the limit switch for the dressing finger indicated it was down, the "B" carriage would move "Y" to the target pin. The "A" carriage dressing finger would then pivot down, and the "A" carriage would move "Y" to its target pin, still pulling supply wire as it movedToshiba PA3399U-2BRS battery .
Once all wrapping bits and dressing fingers were in position, the cut and strip assembly would retract, stripping the trailing edge of the wire on the "A" side (and simultaneously stripping the leading edge of the next wire). The "A" gripper would clamp the wire against the wrapping bit Toshiba Satellite A200 Battery ,
and the wrapping tools would close the bits, which meant the outer bit sleeves would retract, pulling both wire ends up into the bits. Once the wire was safely loaded into the wrapping bits, the "A" and "B" grippers would open, and the A and B tools, along with the dressing fingers, would lower "Z" onto the pins Toshiba Satellite 1200 Battery .
Once the designated "Z" level had been reached (again, sensed by more limit switches) the pneumatic tools would spin, and back pressure would allow the tools to rise up slightly as the wire wrapped around the pins. Waste insulation (transferred from the "A" carriage cut and strip assembly to the "B" carriage during wire feed) Toshiba Satellite M300 Battery
is ejected into the waste container at the far left side of the "B" carriage while the wires are wrapped. Finally, the "A" and "B" tools are raised "Z", dressing fingers are retracted, and the carriages regroup for the next cycle SONY VGP-BPS13A/Q Battery .
Use of Electronic Design Automation
In wire-wrapping, electronic design automation can design the board, and optimize the order in which wires are placed SONY VGP-BPS13A/Q Battery .
The first stage was that a schematic was encoded into a netlist. This step is now done automatically by EDA programs that perform "schematic capture". A netlist is conceptually a list of pins, with each pin having an associated signal name SONY VGP-BPS13B/Q Battery .
The next step was to encode the pin positions of each device. The easy way to do this is to encode lettered rows and numbered columns where the devices should go. The computer then assigns pin 1 of each device in the bill of materials to an intersection, and renames the devices in the bill of materials by their row and column SONY VGP-BPS13B/Q Battery .
The computer would then "explode" the device list into a complete pin list for the board by using templates for each type of device. A template is map of a device's pins. It can be encoded once, and then shared by all devices of that type SONY VGP-BPS13/Q Battery .
Some systems optimized the design by experimentally swapping the positions of parts and logic gates to reduce the wire length. After each movement, the associated pins in the netlist would be renamed. Some systems could also automatically discover power pins in the devices, and generate wires to the nearest power pins SONY VGP-BPS13/Q Battery .
The computer program then merges the netlist (sorted by pin name) with the pin list (sorted by pin name), transferring the physical coordinates of the pin list to the netlist. The netlist is then resorted, by net name SONY VGP-BPS21A/B Battery .
The programs then try to reorder each net in the signal-pin list to "route" each signal in the shortest way. The routing problem is equivalent to the travelling salesman problem, which is NP complete, and therefore not amenable to a perfect solution on a reasonable time scale SONY VGP-BPS21/S Battery .
One practical routing algorithm is to pick the pin farthest from the center of the board, then use a greedy algorithm to select the next-nearest pin with the same signal name.
Once routed, each pair of nodes in a net becomes a wire, in a "wire list" SONY VGP-BPS21B Battery .
The computer then reads incidental information (wire color, order in the net, length of the wire, etc) in the netlist and interprets it to renumber the wire list to optimize the ordering and direction of wires during production. The wire list is then resorted by the wire numbers SONY VGP-BPS21A Battery .
For example, wires are always "top and bottomed". That is, wires alternate between high and low as they connect a series of pins. This lets a repair or modification occur with the removal of at most three wires SONY VGP-BPS21 Battery .
Long wires are usually placed first within a level, so that shorter wires will hold longer wires down. This reduces vibration of the longer wires, making the board more rugged in a vibrating environment such as a vehicle Sony VGP-BPS21A/B Battery .
Placing all the wires of a certain size makes it easier for a manual or semiautomated wire-wrapping machine to use precut wire. This especially speeds up manual wrapping.
Wires of different colors can also be placed together. Most wires are blue Sony VGP-BPS21/S Battery .
Power and ground wires are often made with red and black. Clock wires (or other wires needing special routing) are often made yellow or white. Twisted pairs are usually black and white Sony VGP-BPS21A Battery .
Another optimization is that within each size and color of wire, the computer selects the next wire so that the wrap head moves to the nearest pin. This can save up to 40% of the wrap time, almost getting two wire-wrap machines for the price of one. It also reduces wear on the wire-wrap machines Sony VGP-BPS21 Battery .
Finally, the direction of placing a wire can be optimized for right-handed wire-wrap people, so that wires are placed from right to left. In a semi-automated wire-wrap system, this means that the wrap head moves away from the user's hand when placing a wire. The user can then use their strong hand and eye to route the wire Sony Vaio PCG-5G2L Battery .
Lastly, the sorted, optimized wire list is then printed out for use by machine operators, and turned into a tape or card deck for the machine. Machine-readable copies of this valuable production data are often archived at the same time.
Point-to-point construction is the way most electronics circuits were constructed before the 1950s Sony Vaio PCG-5G3L Battery.
Point-to-point construction is still used to construct prototype equipment with few or heavy electronic components.
Before point-to-point connection, electrical assemblies used screws or wire nuts to hold wires to an insulating wooden or ceramic board Sony Vaio PCG-5J1L Battery .
The resulting devices were prone to fail from corroded contacts, or mechanical loosening of the connections. Early premium marine radios, especially from Marconi, sometimes used welded copper in the bus-bar circuits, but this was expensive.
Point-to-point construction uses terminal strips (sometimes called 'tag boards') or turret boards Sony Vaio PCG-5K2L Battery .
The crucial invention was to apply soldering to electrical assembly. In soldering, an alloy of tin and lead, or later bismuth and tin, is melted and adheres to other, nonmolten metals, such as copper or tinned steel. Solder makes a strong electrical and mechanical connection Sony Vaio PCG-5J2L Battery .
Terminal strip construction
Point-to-point construction uses terminal strips (also called 'tag boards'). A terminal strip is a stamped strip of tin-plated loops of copper. It is mounted in a way that electrically insulates each loop from the others Sony Vaio PCG-5K1L Battery .
The metal loops are mounted on a cheap, heat-resistant material, usually synthetic-resin bonded paper (FR-2), or bakelite reinforced with cotton, or sometimes paxolin. The insulator has an integral mounting bracket, sometimes shorted to one or more of the stamped loops to ground them to the chassis Sony Vaio PCG-6S2L Battery .
The chassis was constructed first, from sheet metal or wood. Insulated terminal strips were then riveted, nailed or screwed to the underside or interior of the chassis. Transformers, large capacitors, Tube sockets and other large components were mounted to the top of the chassis .hdd-shop.co.uk/sony-vaio-pcg-6s3l-battery.html">Sony Vaio PCG-6S3L Battery .
Their wires were led through holes to the underside or interior. The wires of electronic components were physically looped through the terminals and soldered to them. Small electronic components were mounted by twisting their wires around terminals and soldering Sony Vaio PCG-6V1L Battery .
Professional electronics assemblers used to operate from books of photographs and follow an exact assembly sequence to assure that they did not miss any components. Although this process is error-prone and nearly impossible to automate, it is quite good for building small numbers of units when labor costs are low Sony Vaio PCG-6W1L Battery .
Point-to-point construction continued to be used for high quality tube electronics even after the invention of printed circuit boards. The heat of the tubes can degrade the circuit boards and cause them to become brittle and break. Circuit board degradation is often seen on inexpensive tube radios produced in the 1960s, especially around the hot output and rectifier tubes Sony Vaio PCG-6W2L Battery .
The American manufacturer Zenith continued to use point-to-point wiring in its tube based television sets until the early 1970s.
Today, audiophile equipment, such as amplifiers, may be point to point wired using terminal pins Sony Vaio PCG-6W3L Battery .
Whilst many of these units are produced in very small quantities, it is perfectly possible for the public to produce commercial quality printed circuit boards using free design software and online prototyping printers. The point-to-point style is retained instead as mark of quality Sony Vaio PCG-7111L Battery ,
as the connections between components are as thick as their lead out wires will allow and usually short, involving no tracks and few jumpers between points. This is desired as a common goal of audiophile equipment is to have the absolute minimum resistance possible where it is not controllable or needed, which is provided by the thick 'solid' wiring method Sony Vaio PCG-7112L Battery ;
a common complaint against PCB layouts being that the tracks have a very small cross sectional area. Short, straight leads also produce the lowest values of inductance. With the leads being suspended in air, they have a minimal amount of capacitance, where as PCBs can suffer from capacitive effects between the layers Sony Vaio PCG-7113L Battery .
As silver is a slightly better conductor than copper, very expensive capacitors and resistors will be made from pure silver and feature silver lead outs. The slight increase in conductivity is not commercially worthwhile, or necessary, for the majority of electronics and so PCB manufacturers do not offer it as a standard option for the conductive material Sony Vaio PCG-7133L Battery .
But the point to point method allows the producer to have an essentially pure silver path between components.
As with the gain in conductivity when using copper, the electrical gains with regards to resistance, inductance, capacitance and so on are often of little importance to most electronics Sony Vaio PCG-7Z2L Battery .
However, they are extremely important at high frequencies, as frequency is a parameter in defining how currents and voltages interact with these properties. The effects can be so pronounced as to cause high frequency equipment to catastrophically fail with regards to performance if improperly laid out, regardless of component choice and the circuit's logic Sony Vaio PCG-8Y1L Battery .
As a result, it is still possible to see a direct, point-to-point, straight, heavy line layout used in high performance radio frequency equipment, particularly as the frequencies approach the gigahertz band. A blend of the two methods if used in many of these cases, where a ceramic board is used featuring tracks, but with the point-to-point layout logic Sony Vaio PCG-8Y2L Battery .
The difference between the values is small, and the audio spectrum is orders of magnitude below the radio frequencies, making the measurable difference between a PCB and point to point terminal method vanishingly minute in many cases. When the current is constant DC Sony Vaio PCG-8Z1L Battery ,
the differences become essentially zero (bar the effect of DC resistance) as this has frequency of zero, meaning the inductances and capacitances are being multiplied by zero, which will give a zero result.
Despite its often superior electrical properties (and disregarding its bulky, often messy appearance) Sony Vaio PCG-8Z2L Battery ,
this method of wiring is by far and a way one of the most simple to put together and solder, as it has a basic nature to it and features large, easily handled and heated components and posts. More difficult than the actual assembly of a point-to-point board is usually the design SONY VAIO VGN-FW31J Battery ,
as boards are usually laid out as a 'ladder' of side by side elements, which may need connecting to others that aren't adjacent to themselves; requiring a jumper between the two. The art in a layout is the minimization of these jumpers (the wiring complexity)SONY VAIO VGN-FW31E Battery .
This method of wiring (be it between terminals, components or leads) has one well known disadvantage in that the parasitic resistance of PCBs, poorer conductors and longer leads can actually add stability to a circuit. By reducing it close to zero, capacitive and inductive elements within the circuit may go into resonance SONY VAIO VGN-FW31B Battery ,
with the designer having to purposefully add a resistor at a later date.
Placing the completed unit in an enclosure protects it from mechanical damage when the chassis is mounted in a piece of furniture or an equipment rack SONY VAIO VGN-FW31M Battery ,
prevents foreign objects which may alter the electrical characteristics of the circuits and interfere with proper operation (such as by causing short circuits or altering electromagnetic fields), and protects humans and animals from contact with potentially dangerous voltages which may cause an electric shock while the machine is operating and from sharp edges and points on the assembly which could cause physical injury such as cuts SONY VAIO VGN-FW31Z Battery .
Some large brand names still use point-to-point boards, but usually for special product lines. Marshall, who famously produce guitar amplifiers, have recently released reissues of their older models featuring point to point boards SONY VAIO VGN-FW38M Battery .
At audio frequencies, it is highly debatable whether or not the any of the electrical gains of using this method are in any way tangible, but the method carries a weight of originality and solid, hands-on construction that implies more care and higher quality components have been used SONY VAIO VGN-AW41JF Battery .
Marshall's standard product line has been for many decades, and still is, PCB based. When it was realized mounting thermionic valves directly to the PCB caused heat issues, manufacturers of audio equipment like this began mounting the ceramic connectors for the valves on the metal chassis, running lead out wires to the PCB below SONY VAIO VGN-AW41JF/H Battery .
This allows them to mass produce the complex boards and still create a product that will last with a minimal amount of manual soldering involved.
Dead bug' construction
For hobbyist work, free-form construction can be used in cases where a PCB would be too big or too much work for a small number of components SONY VAIO VGN-AW41MF Battery .
This is sometimes called "dead bug style" as the ICs are flipped upside-down with their pins sticking up into the air, evoking the image of the upturned body of an expired insect. While it is often messy-looking, error-prone, and difficult to repair, this can be used to make more compact circuits than other methods SONY VAIO VGN-AW41MF/H Battery .
This is often used in BEAM robotics and in RF circuits where component leads must be kept short. One advantage is the ease with which wire wrap connections may be made to components when resistor and capacitor leads are bent to a U shape and also glued in place SONY VAIO VGN-FW30B Battery .
Stripboard is a widely-used type of electronics prototyping board characterized by a 0.1 inch (2.54 mm) regular (rectangular) grid of holes, with wide parallel strips of copper cladding running in one direction all the way across one side of the board SONY VAIO VGN-FW50B Battery .
It is usually known by the name Veroboard, which is a trademark, in the UK, of British company Vero Technologies Ltd, & Pixel Print LTD Canada.
In using the board, breaks are made in the tracks, usually around holes, to divide the strips into multiple electrical nodes SONY VAIO VGN-FW51B/W Battery .
With care, it is possible to break between holes to allow for components that have two pin rows only one position apart such as twin row headers for IDCs.
A related product is called perfboard (short for perforated board) SONY VAIO VGN-FW51MF Battery .
This is like a Veroboard but each hole has an isolated copper pad rather than a default pattern of copper tracks. Perfboard is also widely used for electrical prototyping, generally with techniques such as miniature point to point wiring, wire wrapping, or a wiring pencil SONY VAIO VGN-FW51MF/H Battery .
Stripboard is available from many different vendors. All versions have copper strips on one side. Some are made using printed circuit board etching and drilling techniques, although some have milled strips and punched holes. The original Veroboard used FR-2 synthetic-resin-bonded paper (SRBP) (also known as phenolic board) as the base board material SONY VAIO VGN-FW51ZF Battery.
Some versions of stripboard now use higher quality FR-4 (fiberglass-reinforced epoxy laminate) material.
Stripboard holes are drilled on 0.1 inch (2.54 mm) centers. This spacing allows components having pins with a 0.1 inch (2.54 mm) spacing to be inserted SONY VAIO VGN-FW51ZF/H Battery .
Compatible parts include DIP ICs, sockets for ICs, some types of connectors, and other devices.
The components are usually placed on the plain side of the board, with their leads protruding through the holes SONY VAIO VGN-FW52JB Battery .
The leads are then soldered to the copper tracks on the other side of the board to make the desired connections, and any excess wire is cut off. The continuous tracks may be easily and neatly cut as desired to form breaks between conductors using a 5 mm twist drill, a hand cutter made for the purpose, or a knife SONY VAIO VGN-FW54FB Battery .
Tracks may be linked up on either side of the board using wire. With practice, very neat and reliable assemblies can be created, though such a method is labour-intensive and therefore unsuitable for production assemblies except in very small quantity SONY VAIO VGN-FW70DB Battery .
External wire connections to the board are made either by soldering the wires through the holes or, for wires too thick to pass through the holes, by soldering them to specially made pins called Veropins which fit tightly into the holes. Alternatively, some types of connectors have a suitable pin spacing to be inserted directly into the board SONY VAIO VGN-FW71DB/W Battery .
Stripboards have evolved over time into several variants and related products. For example, a larger version using a 0.15 inch (3.81 mm) grid and larger holes is available, but is generally less popular (presumably because it doesn't match up with standard IC pin spacing). Stripboard is not designed for surface-mountcomponents SONY VAIO VGN-FW72JGB Battery .
For high density prototyping, especially of digital circuits, wire wrap is faster and more reliable than Stripboard for experienced personnel.
Veroboard is similar in concept and usage to breadboard, but is cheaper and more permanent SONY VAIO VGN-FW73JGB Battery —
connections are soldered and while some limited reuse may be possible, more than a few cycles of soldering and desoldering are likely to render both the components and the board unusable. In contrast, breadboard connections are held by friction, and the breadboard can be reused many times SONY VAIO VGN-FW74FB Battery .
However, a breadboard is not very suitable for prototyping that needs to remain in a set configuration for an appreciable period of time nor for physical mock-ups containing a working circuit or for any environment subject to vibration or movement SONY VAIO VGN-FW81HS Battery .
Stripboards have further evolved into a larger class of prototype boards, available in different shapes and sizes, with different conductive trace layouts. For example, one variant is called a TriPad board. This is similar to stripboard, except that the conductive tracks do not run continuously along the board but are broken into sections SONY VAIO VGN-FW81NS Battery ,
each of which spans three holes. This allows the legs of two or three components to be easily linked together in the circuit conveniently without the need for track breaks to be made. However, in order to link more than three holes together, wire links or bridges must be formed and this can result in a less compact layout than is possible with ordinary stripboard SONY VAIO VGN-FW81S Battery .
Other prototype board variants have generic layouts to simplify building prototypes with integrated circuits, typically in DIP shapes, or with transistors (pads forming triangles). In particular, some boards mimic the layout of breadboards, to simplify moving a non-permanent prototype on a breadboard to a permanent construction on a PCB SONY VAIO VGN-FW82DS Battery .
Some types of boards have patterns for connectors on the periphery, like DB9 or IDCC headers, to allow connectors with non-standard pin spacings to be easily used. Some come in special physical shapes, to be used to prototype plug-in boards for computer bus systems SONY VAIO VGN-FW82JS Battery .
Liquid helium, colder than liquid nitrogen, has also been used for cooling. Liquid helium evaporates at -269 °C, and temperatures ranging from -230 to -240 °C have been measured from the heatsink SONY VAIO VGN-FW82XS Battery .
Softcooling is the practice of utilizing software to take advantage of CPU power saving technologies to minimize energy use. This is done using halt instructions to turn off or put in standby state CPU subparts that aren't being used or by underclocking the CPU SONY VAIO VGN-FW83DS Battery .
Undervolting is a practice of running the CPU or any other component with voltages below the device specifications. An undervolted component draws less power and thus produces less heat SONY VAIO VGN-FW83JS Battery .
The ability to do this varies by manufacturer, product line, and even different production runs of the same exact product (as well as that of other components in the system), but modern processors are typically shipped with voltages higher than strictly necessarySONY VAIO VGN-FW83XS Battery .
This provides a buffer zone so that the processor will have a higher chance of performing correctly under sub-optimal conditions, such as a lower quality mainboard (motherboard). However, too low a voltage will not allow the processor to function correctly, producing errors, system freezes or crashes, or the inability to turn the system on SONY VAIO VGN-FW90NS Battery .
Undervolting too far does not typically lead to hardware damage, though in worst-case scenarios, program or system files can be corrupted.
This technique was generally employed by those seeking low-noise systems, as less cooling is needed because of the reduction of heat production SONY VAIO VGN-FW90S Battery .
Since the popularity of hand-held or remote computers (Unmanned vehicles, mobile & cordless phones/camera/viewers, etc), undervolting is used to prolong battery endurance.
Integrated chip cooling techniques
Conventional cooling techniques all attach their “cooling” component to the outside of the computer chip, or via IHS and/or heat sinks SONY VAIO VGN-FW91NS Battery .
This “attaching” technique will always exhibit some thermal resistance, reducing its effectiveness. The heat can be more efficiently and quickly removed by directly cooling the local hot spots. At these locations, power dissipation of over 300W/cm2(typical CPU are less than 100W/cm2, although future systems are expected to exceed 1000W/cm2 ) can occur SONY VAIO VGN-FW91S Battery .
This form of local cooling is essential to developing high power density chips. This ideology has led to the investigation of integrating cooling elements into the computer chip. Currently there are two techniques: micro-channel heat sinks, and jet impingement cooling SONY VAIO VGN-FW92DS Battery .
In micro-channel heat sinks, channels are fabricated into the silicon chip (CPU), and coolant is pumped through them. The channels are designed with very large surface area which results in large heat transfers. Heat dissipation of 3000W/cm2 has been reported with this technique SONY VAIO VGN-FW92JS Battery .
In comparison to the Sun power density of around 7400W/cm2. The heat dissipation can be further increased if two-phase flow cooling is applied. Unfortunately the system requires large pressure drops, due to the small channels, and the heat flux is lower with dielectric coolants used in electronic cooling SONY VAIO VGN-FW93DS Battery .
Another local chip cooling technique is jet impingement cooling. In this technique, a coolant is flown through a small orifice to form a jet. The jet is directed toward the surface of the CPU chip, and can effectively remove large heat fluxes. Heat dissipation of over 1000W/cm2has been reported SONY VAIO VGN-FW93JS Battery .
The system can be operated at lower pressure in comparison to the micro-channel method. The heat transfer can be further increased using two-phase flow cooling and by integrating return flow channels (hybrid between micro-channel heat sinks and jet impingement cooling) SONY VAIO VGN-FW139E/H Battery .
Cooling and overclocking
Extra cooling is usually required by those who run parts of their computer (such as the CPU and GPU) at higher voltages and frequencies than manufacturer specifications call for, called overclocking SONY VAIO VGN-FW145E/W Battery .
Increasing performance by this modification of settings results in a greater amount of heat generated and thus increasing the risk of damage to components and/or premature failure.
The installation of higher performance, non-stock cooling may also be considered modding SONY VAIO VGN-FW190EBH Battery .
Many overclockers simply buy more efficient, and often, more expensive fan and heat sink combinations, while others resort to more exotic ways of computer cooling, such as liquid cooling, Peltier effect heatpumps, heat pipe or phase change cooling.
There are also some related practices that have a positive impact in reducing system temperatures SONY VAIO VGN-FW190EDH Battery :
Heat sink lapping
Heat sink lapping is the smoothing and polishing of the contact (bottom) part of a heat sink to increase its heat transfer efficiency. The desired result is a contact area which has a more even surface, as a less even contact surface creates a larger amount of insulating air between the heat sink and the computer part it is attached to SONY VAIO VGN-FW21E Battery .
Polishing the surface using a combination of fine sandpaper and abrasive polishing liquids can produce a mirror-like shine, an indicator of a very smooth metal surface. Even a curved surface can become extremely reflective, yet not particularly flat, as is the case with curved mirrors SONY VAIO VGN-FW21J Battery ;
thus heat sink quality is based on overall flatness, more than optical properties. Lapping a high quality heat sink can damage it, because, although the heat sink may become shiny, it is likely that more material will be removed from the edges, making the heat sink less effective overall SONY VAIO VGN-FW21L Battery .
If attempted, a piece of float glass should be used, as it self-levels as it cools and offers the most economical solution to producing a perfectly flat surface.
Use of exotic thermal conductive compounds
Some overclockers use special thermal compounds whose manufacturers claim to have a much higher efficiency than stock thermal pads SONY VAIO VGN-FW21M Battery .
Heat sinks clean of any grease or other thermal transfer compounds have a very thin layer of these products applied, and then are placed normally over the CPU. Many of these compounds have a high proportion of silver as their main ingredient due to its high thermal conductivity SONY VAIO VGN-FW21Z Battery .
The resulting difference in the temperature of the CPU is measurable (several celsius degrees), so the heat transfer does appear to be superior to stock compounds. Some people experience negligible gains and have called to question the advantages of these exotic compounds, calling the style of application more important than the compound itself SONY VAIO VGN-FW25T/B Battery .
Also note that there may be a 'setting' or 'curing' period and negligible gains may improve over time as the compound reaches its optimum thermal conductivity.
Use of rounded cables
Most older PCs use flat ribbon cables to connect storage drives (IDE or SCSI) SONY VAIO VGN-FW26T/B Battery .
These large flat cables greatly impede airflow by causing drag and turbulence. Overclockers and modders often replace these with rounded cables, with the conductive wires bunched together tightly to reduce surface area. Theoretically, the parallel strands of conductors in a ribbon cable serve to reduce crosstalk SONY VAIO VGN-FW27/B Battery
(signal carrying conductors inducing signals in nearby conductors), but there is no empirical evidence of rounding cables reducing performance. This may be because the length of the cable is short enough so that the effect of crosstalk is negligible SONY VAIO VGN-FW27/W Battery .
Problems usually arise when the cable is not electromagnetically protected and the length is considerable, a more frequent occurrence with older network cables.
These computer cables can then be cable tied to the chassis or other cables to further increase airflow SONY VAIO VGN-FW27T/H Battery .
This is less of a problem with new computers that use Serial ATA which has a much narrower cable.
The colder the cooling medium (the air), the more effective the cooling SONY VAIO VGN-FW29/B Battery .
Cooling air temperature can be improved with these guidelines:
- Supply cool air to the hot components as directly as possible. Examples are air snorkels and tunnels that feed outside air directly and exclusively to the CPU or GPU cooler SONY VAIO VGN-FW290JRB Battery .
- For example, the BTXcase design prescribes a CPU air tunnel.
- Expel warm air as directly as possible. Examples are: Conventional PC (ATX) power supplies blow the warm air out the back of the case SONY VAIO VGN-FW290JTB Battery .
- Many dual-slot graphics card designs blow the warm air through the cover of the adjacent slot. There are also some aftermarket coolers that do this. Some CPU cooling designs blow the warm air directly towards the back of the case, where it can be ejected by a case fan SONY VAIO VGN-FW290JTH Battery .
- Air that has already been used to spot-cool a component should not be reused to spot-cool a different component (this follows from the previous items). The ATX case design can be said to violate this rule, since the power supply gets its "cool" air from the inside of the case, where it has been warmed up already SONY VAIO VGN-FW52JB Battery .
- The BTX case design also violates this rule, since it uses the CPU cooler's exhaust to cool the chipset and often the graphics card.
- Prefer cool intake air, avoid inhaling exhaust air (outside air above or near the exhausts) SONY VAIO VGN-FW51B/W Battery .
- For example, a CPU cooling air duct at the back of a tower case would inhale warm air from a graphics card exhaust. Moving all exhausts to one side of the case, conventionally the back, helps to keep the intake air cool.
- Hiding cables behind motherboard tray or simply apply ziptie and tucking cables away to provide unhindered airflow SONY VAIO VGN-FW50B Battery .
Fewer fans strategically placed will improve the airflow internally within the PC and thus lower the overall internal case temperature in relation to ambient conditions. The use of larger fans also improves efficiency and lowers the amount of waste heat along with the amount of noise generated by the fans while in operation SONY VAIO VGN-FW47GYH Battery .
There is little agreement on the effectiveness of different fan placement configurations, and little in the way of systematic testing has been done. For a rectangular PC (ATX) case, a fan in the front with a fan in the rear and one in the top has been found to be a suitable configuration SONY VAIO VGN-FW465GJB Battery .
However, AMD's (somewhat outdated) system cooling guidelines notes that "A front cooling fan does not seem to be essential. In fact, in some extreme situations, testing showed these fans to be recirculating hot air rather than introducing cool air SONY VAIO VGN-FW465GJ/BE1 Battery ."
It may be that fans in the side panels could have a similar detrimental effect -- possibly through disrupting the normal air flow through the case. However, this is unconfirmed and probably varies with the configuration SONY VAIO VGN-FW465J/B Battery .