Appearance
🎉 your bitcoin🥳
"A large trunk with leather handles A trunk, also known as a travel trunk, is a large cuboid container designed to hold clothes and other personal belongings. They are most commonly used for extended periods away from home, such as for boarding school, or long trips abroad. Trunks are differentiated from chests by their more rugged construction due to their intended use as luggage, instead of the latter's pure storage. Among the many styles of trunks there are Jenny Lind, Saratoga, monitor, steamer or Cabin, barrel-staves, octagon or bevel-top, wardrobe, dome-top, barrel-top, wall trunks, and even full dresser trunks. These differing styles often only lasted for a decade or two as well, and—along with the hardware—can be extremely helpful in dating an unmarked trunk. History and construction Although trunks have been around for thousands of years in China and elsewhere, the most common styles seen and referred to today date from the late 18th century to the early 20th century, when they were supplanted in the market by the cost-effective and lighter suitcase. Trunks were generally constructed with a base trunk box made of pine which was then covered with protective and decorative materials. Some of the earliest trunks are covered with studded hide or leather and look much like the furniture of the same period (which makes sense as trunk manufacturing was sometimes an offshoot of a furniture business.) Later coverings include paper, canvas, plain or embossed tin, with an uncounted assortment of hardware and hardwood slats to keep it all down. They sometimes were made with a small brass handle on top and were made in many sizes. The use of classic trunks for luggage was widespread through the first two decades of the twentieth century but began to fade in popularity thereafter in favor of the modern suitcase. By the end of the 1940s their use had become rare and in modern times is almost unknown. Famous companies There were hundreds of trunk manufacturers in the United States and a few of the larger and well known companies were Rhino Trunk & Case, C.A. Taylor, Haskell Brothers, Martin Maier, Romadka Bros., Goldsmith & Son, Crouch & Fitzgerald, M. M. Secor, Winship, Hartmann, Belber, Oshkosh, Seward, and Leatheroid. One of the largest American manufacturers of trunks at one point — Seward Trunk Co. of Petersburg, Virginia — still makes them for school and camp, and another company — Shwayder Trunk Company of Denver, Colorado — would eventually become Samsonite. Another is the English luxury goods manufacturer H.J. Cave trading since 1839. Their Osilite trunk was used by such famous customers as T.E. Lawrence and Ruth Vincent Some of the better known French trunk makers were Louis Vuitton, Goyard, Moynat, and Au Départ. Only a few remain with the most prominent US company being Rhino Trunk and Case, Inc. They probably manufacture more trunks than any company in the world. Styles and manufacturers The easiest way for the casual observer to date any trunk is still by examining its style, so a short description of each aforementioned major variety follows. Jenny Lind trunks have a distinctive hour glass or keyhole shape when viewed from the side. They were named after the Swedish singer of the same name who toured America in 1850 - 1852 along with PT Barnum. Saratoga trunks were the premium trunks of many makers (or the exclusive design of many premium trunk makers) and actually can encompass nearly every other style of trunk manufactured if loosely defined, although generally they are limited to before the 1880s. The most readily recognizable feature of Saratogas are their myriad (and generally very complex) compartments, trays, and heavy duty hardware. Monitor-tops (incorrectly known as water-fall trunks from the furniture) date from the late 1870s to the late 1910s, and are characterized by their rounded front and rear corners to form a lying-down "D" when viewed from the side. Earlier examples usually included labor-intensive hardwood slats that were curved with the top, while there was a revival much later with rarer, all-metal ones being constructed. A steamer trunk dating from the late 1890s to early 1900s. Steamer trunks (named after their location of storage in the cabin of a steam ship, or "steamer") which are sometimes referred to as flat-tops, first appeared in the late 1870s, although the greater bulk of them date from the 1880–1920 period. They are distinguished by either their flat or slightly curved tops and were usually covered in canvas, leather or patterned paper and about tall to accommodate steamship luggage regulations. There has been much debate and discourse on what these types of trunks are actually called. In some old catalogs, these trunks were called "packers", and the "steamer" trunk actually referred to a trunk that is often called a cabin trunk. An orthodox name for this type of trunk would be a "packer" trunk, but since it has been widely called a steamer for so long, it is now a hallmark of this style. A low-profile cabin trunk from the early 1900s Cabin trunks, which are sometimes called "true" steamer trunks, were the equivalent of today's carry-on luggage. They were low-profiled and small enough to fit under the berths of trains or in the cabin of a steamer, hence their name. Most were built with flat tops and had inner tray compartments to store the owner's valuables deemed too precious to keep stowed away in the baggage (luggage) car or ship's hold. A hat trunk (box) dating from the 1890s, with "cube-shaped" construction Hat trunks were square shaped trunks that were popular in the 1860s to the 1890s. Today, they are mostly called "half-trunks". They were smaller and easier to carry, and could hold up to six hats or bonnets. Most were flat tops, but some had domed lids (which were very elegant). This trunk style was popular with Victorian women, hence antique trunk labels often calling this type a "ladies' trunk". Hat trunks generally sell for more than any other average trunk style because they are smaller and are rather rare to find. An example of a barrel- stave trunk Barrel-staves are sometimes referred to as a form of dome-top trunk, but generally date from a decade or more earlier and are notable for having horizontal slats instead of vertical, giving it a distinctive look and construction. These were generally made from the late 1870s to the mid-1880s. Bevel-tops are separated into an early and a late (or revival) period, the former generally dating from the 1870–1880 period, and the latter from 1890 to 1900. They are characterized by a distinct trapezoidal shape when viewed from the side, although the earlier period tended to have a much shorter flattened top section than the later did. These tend to be extremely rare, although are not as popular or sought-after as many of the other varieties. Wardrobe trunks generally must be stood on end to be opened and have drawers on one side and hangers for clothes on the other. Many of the better wardrobe lines also included buckles/tie-downs for shoes, removable suitcases/briefcases, privacy curtains, mirrors, make-up boxes, and just about anything else imaginable. These are normally very large and heavy as they were used for extended travel by ship or train. Rhino Trunk and Case, Inc. still manufactures many styles of wardrobe trunks at their Rochester, NY facility. Two examples of dome-top trunks: one is a vertical slat trunk, the other is a barrel-stave trunk A dome-top trunk has a high, curved top that can rise up to heights of . A variety of construction methods—including cuffing, molded ply, barrel construction, and so forth—were used to form the inner boxes. Included in this classification are camel-backs, which are distinguished by having a central, vertically running top slat that is higher than its fellows, hunch-backs or hump-backs which is the same but has no slat in the center of the top, and barrel-tops (not to be confused with barrel staves), which have high arching slats that are all the same height, a distinction that can be discerned by laying a ruler flat across the tops of the slats. These trunks date from 1870s-1900s, although there are a few shops still manufacturing them today. They are not only the most common trunks referred to as antique, but also are among the most popular. Wall trunks are made with a special hinges so that when opened the trunk could still be put flat up against a wall. The two main manufacturers include Clinton and Miller, which can be easily noted by the name on the hinges. In good condition these are comparatively sought-after trunks for a specialty type, although are in the middling range when it comes to price. A Homer Young dresser (theatrical) trunk Dresser trunks also known as pyramidal trunks, due to their shape, are a unique form of wall-trunk that generally date from the 1900–1910 era. They are characterized by a lid that opens up nearly the entire front half of the trunk, allowing it to rest on the bottom. Two prominent manufacturers of this trunk style were F. A. Stallman and Homer Young & Co. Oak-slat trunks incorporating many construction-styles (e.g. dome-top, flat-top, beveled-top) were built on a wooden frame, where the malletier would fit thin oak slats vertically side-by-side until the entire trunk was covered. To a Victorian, this would show the complexity of the trunk and astuteness of the malletier, and was an indication of wealth to any purchaser. Oak-slat trunks were built by several companies, including the Excelsior Company, MM (Martin Maier) Company, Clinton Wall Trunk Manufactory, and El Paso Slat Trunk Company. Some oak-slat trunks were made with alternating colors on the vertical slats. Footlockers are trunk-like pieces of luggage used in military contexts. Generally these are designed for economy, ruggedness, and ease of transport rather than aesthetic qualities. During the steamer trunk restoration process when the inside paper covering is removed, dated notes in lead pencil made by the original craftsman may be found, as well as the circular saw blade impressions made on the rough-cut wood at the saw mill, both of which give added character and value to the restored trunk. Types of tray compartments There were numerous tray and lid compartments in Victorian trunks, ranging from basic to complex. A basic tray system comprised a hat box, a shirt compartment, a coin box, and a document box. A complex tray system, however, could consist two hat boxes, several other shirt compartments, a coin box, several document boxes and even secret compartments strategically placed so that people of unwanted access would pass up if not wary. Beautiful lithographs would be placed over the lids or dome of the trunk and truly capture the Victorian aesthetic of that day. There were numerous chromolithographs that a trunk maker could use, and they could be indicative of who the trunk was intended for, such as ladies or men. A bride's chest usually had a lot of floral pictures or lithographs of other ladies, while men's had pictures of "village" or country scenes. It was up to the malletier what to put on the lids and trays. See also *Chest (furniture) *Martin Maier, a trunk maker in Detroit (1865–1915) *M. M. Secor, a trunk maker in Racine, Wisconsin *Sljeme (company) References External links Category:Luggage "
"A Class B push–pull output driver using a pair of complementary PNP and NPN bipolar junction transistors configured as emitter followers A push–pull amplifier is a type of electronic circuit that uses a pair of active devices that alternately supply current to, or absorb current from, a connected load. This kind of amplifier can enhance both the load capacity and switching speed. Push–pull outputs are present in TTL and CMOS digital logic circuits and in some types of amplifiers, and are usually realized as a complementary pair of transistors, one dissipating or sinking current from the load to ground or a negative power supply, and the other supplying or sourcing current to the load from a positive power supply. A push–pull amplifier is more efficient than a single-ended "class-A" amplifier. The output power that can be achieved is higher than the continuous dissipation rating of either transistor or tube used alone and increases the power available for a given supply voltage. Symmetrical construction of the two sides of the amplifier means that even- order harmonics are cancelled, which can reduce distortion.Joe Carr, RF Components and Circuits, Newnes, page 84 DC current is cancelled in the output, allowing a smaller output transformer to be used than in a single- ended amplifier. However, the push–pull amplifier requires a phase-splitting component that adds complexity and cost to the system; use of center-tapped transformers for input and output is a common technique but adds weight and restricts performance. If the two parts of the amplifier do not have identical characteristics, distortion can be introduced as the two halves of the input waveform are amplified unequally. Crossover distortion can be created near the zero point of each cycle as one device is cut off and the other device enters its active region. A vacuum tube amplifier often used a center-tapped output transformer to combine the outputs of tubes connected in push–pull. 6BQ5 output tubes per channel Push–pull circuits are widely used in many amplifier output stages. A pair of audion tubes connected in push–pull is described in Edwin H. Colpitts' US patent 1137384 granted in 1915, although the patent does not specifically claim the push–pull connection.Donald Monroe McNicol, Radios' Conquest of Space: The Experimental Rise in Radio Communication Taylor & Francis, 1946 page 348 The technique was well-known at that time http://www.leagle.com/xmlResult.aspx?page=5&xmldoc;=193278360F2d723_1537.xml&docbase;=CSLWAR1-1950-1985&SizeDisp;=7 WESTERN ELECTRIC CO. v. WALLERSTEIN retrieved 12/12/12 and the principle had been claimed in an 1895 patent predating electronic amplifiers.US Patent 549,477 Local Transmitter Circuit for Telephones., W. W. Dean Possibly the first commercial product using a push–pull amplifier was the RCA Balanced amplifier released in 1924 for use with their Radiola III regenerative broadcast receiver.Radios - RCA Radiola Balanced Amplifier 1924 By using a pair of low-power vacuum tubes in push–pull configuration, the amplifier allowed the use of a loudspeaker instead of headphones, while providing acceptable battery life with low standby power consumption.Gregory Malanowski The Race for Wireless: How Radio Was Invented (or Discovered?), AuthorHouse, 2011 pages 66-67, page 144 The technique continues to be used in audio, radio frequency, digital and power electronics systems today. Digital circuits The TTL output stage is a rather complicated push–pull circuit known as a 'totem pole output' (the transistors, diode, and resistor in the right-most slice of this TTL logic gate circuit). It sinks currents better than it sources current. A digital use of a push–pull configuration is the output of TTL and related families. The upper transistor is functioning as an active pull-up, in linear mode, while the lower transistor works digitally. For this reason they are not capable of supplying as much current as they can sink (typically 20 times less). Because of the way these circuits are drawn schematically, with two transistors stacked vertically, normally with a level shifting diode in between, they are called "totem pole" outputs. A disadvantage of simple push–pull outputs is that two or more of them cannot be connected together, because if one tried to pull while another tried to push, the transistors could be damaged. To avoid this restriction, some push–pull outputs have a third state in which both transistors are switched off. In this state, the output is said to be floating (or, to use a proprietary term, tri- stated). The alternative to a push–pull output is a single switch that connects the load either to ground (called an open collector or open drain output) or to the power supply (called an open-emitter or open-source output). Analog circuits A conventional amplifier stage which is not push–pull is sometimes called single-ended to distinguish it from a push–pull circuit. In analog push–pull power amplifiers the two output devices operate in antiphase (i.e. 180° apart). The two antiphase outputs are connected to the load in a way that causes the signal outputs to be added, but distortion components due to non-linearity in the output devices to be subtracted from each other; if the non-linearity of both output devices is similar, distortion is much reduced. Symmetrical push–pull circuits must cancel even order harmonics, like f2, f4, f6 and therefore promote odd order harmonics, like (f1), f3, f5 when driven into the nonlinear range. A push–pull amplifier produces less distortion than a single-ended one. This allows a class-A or AB push–pull amplifier to have less distortion for the same power as the same devices used in single-ended configuration. Class AB and class B dissipate less power for the same output than class A; distortion can be kept low by negative feedback and by biassing the output stage to reduce crossover distortion. A class - B push–pull amplifier is more efficient than a class-A power amplifier because each output device amplifies only half the output waveform and is cut off during the opposite half. It can be shown that the theoretical full power efficiency (AC power in load compared to DC power consumed) of a push–pull stage is approximately 78.5%. This compares with a class-A amplifier which has efficiency of 25% if directly driving the load and no more than 50% for a transformer coupled output.Maurice Yunik Design of Modern Transistor Circuits, Prentice-Hall 1973 pp. 340-353 A push–pull amplifier draws little power with zero signal, compared to a class-A amplifier that draws constant power. Power dissipation in the output devices is roughly one-fifth of the output power rating of the amplifier. A class-A amplifier, by contrast, must use a device capable of dissipating several times the output power. The output of the amplifier may be direct-coupled to the load, coupled by a transformer, or connected through a dc blocking capacitor. Where both positive and negative power supplies are used, the load can be returned to the midpoint (ground) of the power supplies. A transformer allows a single polarity power supply to be used, but limits the low-frequency response of the amplifier. Similarly, with a single power supply, a capacitor can be used to block the DC level at the output of the amplifier.Donald G. Fink, ed. Electronics Engineer's Handbook, McGraw Hill 1975 pp. 13-23 through 13-24 Where bipolar junction transistors are used, the bias network must compensate for the negative temperature coefficient of the transistors' base to emitter voltage. This can be done by including a small value resistor between emitter and output. Also, the driving circuit can have silicon diodes mounted in thermal contact with the output transistors to provide compensation. = Push–pull transistor output stages = Categories include: Transformer-output transistor power amplifiers It is now very rare to use output transformers with transistor amplifiers, although such amplifiers offer the best opportunity for matching the output devices (with only PNP or only NPN devices required). Totem pole push–pull output stages Two matched transistors of the same polarity can be arranged to supply opposite halves of each cycle without the need for an output transformer, although in doing so the driver circuit often is asymmetric and one transistor will be used in a common-emitter configuration while the other is used as an emitter follower. This arrangement is less used today than during the 1970's; it can be implemented with few transistors (not so important today) but is relatively difficult to balance and to keep a low distortion. Symmetrical push–pull Each half of the output pair "mirror" the other, in that an NPN (or N-Channel FET) device in one half will be matched by a PNP (or P-Channel FET) in the other. This type of arrangement tends to give lower distortion than quasi-symmetric stages because even harmonics are cancelled more effectively with greater symmetry. Quasi- symmetrical push–pull In the past when good quality PNP complements for high power NPN silicon transistors were limited, a workaround was to use identical NPN output devices, but fed from complementary PNP and NPN driver circuits in such a way that the combination was close to being symmetrical (but never as good as having symmetry throughout). Distortion due to mismatched gain on each half of the cycle could be a significant problem. Super-symmetric output stages Employing some duplication in the whole driver circuit, to allow symmetrical drive circuits can improve matching further, although driver asymmetry is a small fraction of the distortion generating process. Using a bridge-tied load arrangement allows a much greater degree of matching between positive and negative halves, compensating for the inevitable small differences between NPN and PNP devices. Square-law push–pull The output devices, usually MOSFETs or vacuum tubes, are configured so that their square-law transfer characteristics (that generate second-harmonic distortion if used in a single-ended circuit) cancel distortion to a large extent. That is, as one transistor's gate-source voltage increases, the drive to the other device is reduced by the same amount and the drain (or plate) current change in the second device approximately corrects for the non-linearity in the increase of the first. = Push–pull tube (valve) output stages = Vacuum tubes (valves) are not available in complementary types (as are pnp/npn transistors), so the tube push–pull amplifier has a pair of identical output tubes or groups of tubes with the control grids driven in antiphase. These tubes drive current through the two halves of the primary winding of a center-tapped output transformer. Signal currents add, while the distortion signals due to the non-linear characteristic curves of the tubes subtract. These amplifiers were first designed long before the development of solid-state electronic devices; they are still in use by both audiophiles and musicians who consider them to sound better. Vacuum tube push–pull amplifiers usually use an output transformer, although Output-transformerless (OTL) tube stages exist (such as the SEPP/SRPP and the White Cathode Follower below). The phase-splitter stage is usually another vacuum tube but a transformer with a center-tapped secondary winding was occasionally used in some designs. Because these are essentially square-law devices, the comments regarding distortion cancellation mentioned above apply to most push–pull tube designs when operated in class A (i.e. neither device is driven to its non-conducting state). A Single Ended Push–Pull (SEPP, SRPP or mu-follower) output stage, originally called the Series-Balanced amplifier (US patent 2,310,342, Feb 1943). is similar to a totem-pole arrangement for transistors in that two devices are in series between the power supply rails, but the input drive goes only to one of the devices, the bottom one of the pair; hence the (seemingly contradictory) Single-Ended description. The output is taken from the cathode of the top (not directly driven) device, which acts part way between a constant current source and a cathode follower but receiving some drive from the plate (anode) circuit of the bottom device. The drive to each tube therefore might not be equal, but the circuit tends to keep the current through the bottom device somewhat constant throughout the signal, increasing the power gain and reducing distortion compared with a true single-tube single-ended output stage. The White Cathode Follower (Patent 2,358,428, Sep 1944 by E. L. C. White) is similar to the SEPP design above, but the signal input is to the top tube, acting as a cathode follower, but one where the bottom tube (in common cathode configuration) if fed (usually via a step-up transformer) from the current in the plate (anode) of the top device. It essentially reverses the roles of the two devices in SEPP. The bottom tube acts part way between a constant current sink and an equal partner in the push–pull workload. Again, the drive to each tube therefore might not be equal. Transistor versions of the SEPP and White follower do exist, but are rare. Ultra-linear push–pull A so-called ultra-linear push–pull amplifier uses either pentodes or tetrodes with their screen grid fed from a percentage of the primary voltage on the output transformer. This gives efficiency and distortion that is a good compromise between triode (or triode- strapped) power amplifier circuits and conventional pentode or tetrode output circuits where the screen is fed from a relatively constant voltage source. See also *Single-ended triode *Push–pull converter for more details on implementation *Open collector References Category:Electronic circuits "
"Smear in Los Angeles from 2005. Wheat paste (also known as flour paste, or simply paste) is a gel or liquid adhesive made from wheat flour or starch and water. It has been used since antiquity for various arts and crafts such as book binding, découpage, collage, papier-mâché, and adhering paper posters and notices to walls. A critical difference among wheat pastes is the division between those made from flour and those made from starch. Vegetable flours contain both gluten and starch. Over time the gluten in a flour paste cross- links, making it very difficult to release the adhesive. Using only starch, a fine quality, fully reversible paste can be produced. The latter is the standard adhesive for paper conservation. Besides wheat, other vegetables also are processed into flours and starches from which pastes can be made: characteristics, such as strength and reversibility, vary with the plant species; manufacturer's processing; and the recipe of the end-user. Uses A common use is to make chains of paper rings made from colored construction paper. It can also be used to create papier-mâché. In the fine arts, wheat starch paste is often used in preparation and presentation. A good wheat starch paste has a strength compatible with many paper artifacts, remains reversible over time, is neither too acidic or alkaline, and is white. Activists and various subculture proponents often use this adhesive to flypost propaganda and artwork. It has also commonly been used by commercial bill posters since the nineteenth century. In particular, it was widely used by nineteenth and twentieth century circus bill posters, who developed a substantial culture around paste manufacture and postering campaigns.The Circus Boys on the Plains, Project Gutenberg e-text, originally published 1911. In the field of alcohol and nightclub advertising, in the 1890s, Henri de Toulouse-Lautrec's posters were so popular that instructions were published on how to peel down the pasted posters without damage. Posters Weren't the Half of Him, New York Times Book Review, 16 January 2000, accessed July 2006. Until the 1970s, commercial poster hangers always "cooked" their own paste, but since then many have bought pre-cooked instant pastes.Ethical Considerations for the Conservation of Circus Posters, WAAC Newsletter, 17(2), May 1995, accessed July 2006 It is applied to the backside of paper then placed on flat surfaces, particularly concrete and metal as it does not adhere well to wood or plastic. Cheap, rough paper such as newsprint, works well, as it can be briefly dipped in the mixture to saturate the fibres. When hanging unauthorized billboards or signage, to reduce the danger of being caught, wheatpasters frequently work in teams or affinity groups. In the United States and Canada, this process is typically called "wheatpasting" or "poster bombing," even when using commercial wallpaper paste instead of traditional wheat paste. In the United Kingdom, commercial wheatpasting is called flyposting and wheatpasting associated with urban art is called paste-up. See also References * Category:Adhesives Category:Visual arts materials Category:Graffiti and unauthorised signage "