AutoCAD Freestyle

Built on the AutoCAD platform, AutoCAD Freestyle is a simplified, low-cost (US$149) application that makes it easy to create accurate, professional-looking 2D drawings and sketches

AutoCAD LT

AutoCAD LT is a lower cost version of AutoCAD with reduced capabilities first released in November 1993. AutoCAD LT, priced at $495, became the first product in the company's history priced below $1000 to bear the name 'AutoCAD'. In addition to being sold directly by Autodesk, it can also be purchased at computer stores, unlike the full version of AutoCAD which must be purchased from official Autodesk dealers. Autodesk developed AutoCAD LT so that they would have an entry-level CAD package to compete in the lower price level.

AutoCAD Origin

AutoCAD was derived from a program called Interact, which was written in a proprietary language (SPL) and ran on the Marinchip Systems 9900 computer (Marinchip was owned by Autodesk co-founders John Walker and Dan Drake.)


When Marinchip Software Partners (later to be renamed Autodesk) was formed, they decided to re-code Interact in C and PL/1 -- C, because it seemed to be the biggest upcoming language, and PL/1. In the end, the PL/1 version was unsuccessful. The C version was, at the time, one of the most complex program in that language to date. Autodesk even had to work with the compiler developer (Lattice) to fix certain limitations to get AutoCAD to run.

AutoCAD

AutoCAD is a CAD (Computer Aided Design or Computer Aided Drafting) software application for 2D and 3D design and drafting. It was developed and sold by Autodesk, Inc. First released in December 1982, AutoCAD was one of the first CAD programs to run on personal computers, notably the IBM PC. At that time, most other CAD programs ran on mainframe computers or mini-computers which were connected to a graphics computer terminal for each user.


Early releases of AutoCAD used primitive entities — lines, polylines, circles, arcs, and text — to construct more complex objects. Since the mid-1990s, AutoCAD has supported custom objects through its C++ Application Programming Interface (API). Modern AutoCAD includes a full set of basic solid modeling and 3D tools. With the release of AutoCAD 2007 came improved 3D modeling, which meant better navigation when working in 3D. Moreover, it became easier to edit 3D models. The mental ray engine was included in rendering, it was now possible to do quality renderings. AutoCAD 2010 introduced parametric functionality and mesh modeling.

AutoCAD supports a number of APIs for customization and automation. These include AutoLISP, Visual LISP, VBA, .NET and ObjectARX. ObjectARX is a C++ class library, which was also the base for products extending AutoCAD functionality to specific fields, to create products such as AutoCAD Architecture, AutoCAD Electrical, AutoCAD Civil 3D, or third-party AutoCAD-based applications.

Currently, AutoCAD only runs under Microsoft Windows operating systems. It is available in 32-bit and in native 64-bit versions. Versions for Unix and Mac OS were released in the 1980s and 1990s, but these were later dropped. AutoCAD can run on an emulator or compatibility layer like VMware Workstation or Wine, albeit subject to various performance issues that can often arise when working with 3D objects or large drawings.

AutoCAD and AutoCAD LT are available for English, German, French, Italian, Spanish, Japanese, Korean, Chinese Simplified, Chinese Traditional, Russian, Czech, Polish, Hungarian, Brazilian, Portuguese, Danish, Dutch, Swedish, Finnish, Norwegian, and Vietnamese. The extent of localization varies from full translation of the product to documentation only. The AutoCAD command set is localized as a part of the software localization.

Electrolytic capacitor

An electrolytic capacitor is a type of capacitor that uses an electrolyte, an ionic conducting liquid, as one of its plates, to achieve a larger capacitance per unit volume than other types. They are often referred to in electronics usage simply as "electrolytics". They are used in relatively high-current and low-frequency electrical circuits, particularly in power supply filters, where they store charge needed to moderate output voltage and current fluctuations in rectifier output. They are also widely used as coupling capacitors in circuits where AC should be conducted but DC should not. There are two types of electrolytics; aluminum and tantalum.

Electrolytic capacitors are capable of providing the highest capacitance values of any type of capacitor. However they have drawbacks which limit their use. The voltage applied to them must be polarized; one specified terminal must always have positive potential with respect to the other. Therefore they cannot be used with AC signals without a DC bias. They also have very low breakdown voltage, higher leakage current and inductance, poorer tolerances and temperature range, and shorter lifetimes compared to other types of capacitors.

History

There is no clear inventor of the electrolytic capacitor. It is one of the many technologies that spent many years as a laboratory curiosity, a classic "solution looking for a problem".

The principle of the electrolytic capacitor was discovered in 1886 by Charles Pollak, as part of his research into anodizing of aluminum and other metals. Pollack discovered that due to the thinness of the aluminum oxide layer produced, there was a very high capacitance between the aluminum and the electrolyte solution. A major problem was that most electrolytes tended to dissolve the oxide layer again when the power is removed, but he eventually found that sodium perborate (borax) would allow the layer to be formed and not attack it afterwards. He was granted a patent for the borax-solution aluminum electrolytic capacitor in 1897.

The first application of the technology was in making starting capacitors for single-phase alternating current (AC) motors. Although most electrolytic capacitors are polarized, that is, they can only be operated with direct current (DC), by separately anodizing aluminum plates and then interleaving them in a borax bath, it is possible to make a capacitor that can be used in AC systems.

Nineteenth and early twentieth century electrolytic capacitors bore little resemblance to modern types, their construction being more along the lines of a car battery. The borax electrolyte solution had to be periodically topped up with distilled water, again reminiscent of a lead acid battery.

The first major application of DC versions of this type of capacitor was in large telephone exchanges, to reduce relay hash (noise) on the 48 volt DC power supply. The development of AC-operated domestic radio receivers in the late 1920s created a demand for large capacitance (for the time) high voltage capacitors, typically at least 4 microfarads and rated at around 500 volts DC. Waxed paper and oiled silk capacitors were available but devices with that order of capacitance and voltage rating were bulky and prohibitively expensive.

The ancestor of the modern electrolytic capacitor was patented by Julius Lilienfeld in 1926. Lilienfeld's design resembled that of a silver mica capacitor, but with electrolyte-soaked paper sheets in place of the mica dielectric. However, it proved impractical to adequately seal the devices, and in the hot conditions inside typical mains-operated radio receivers the capacitors quickly dried out and failed.

Retired US Navy engineer Ralph D. Mershon is credited with developing the first commercially available "radio" electrolytic capacitor that was used in any quantity (although other researchers produced broadly similar devices). The "Mershon Condenser" as it was known (condenser was the earlier term for capacitor) was constructed like a conventional paper capacitor, with two long strips of aluminum foil interwound with strips of insulating paper, but with the paper saturated with electrolyte solution instead of wax. Rather than trying to hermetically seal the devices, Mershon's solution was to simply fit the capacitor into an oversize aluminum or copper can, half-filled with extra electrolyte. These units are referred to as "wet electrolytics," and those with liquid still inside are prized by vintage radio collectors.

"Mershons" were an immediate success and the name "Mershon Condenser" was, for a short time, synonymous with quality radio receivers in the late 1920s. However, due to a number of manufacturing difficulties, their service life turned out to be quite short and Mershon's company went bankrupt in the early 1930s.

It was not until World War II, when sufficient resources were finally applied to finding the causes of electrolytic capacitor unreliability, that they started to become as reliable as they are today. A major advance was the process of etching and pre-anodizing the foil prior to assembly, which allowed the use of much less corrosive electrolyte solutions, which in turn meant the devices could be left unenergized for long periods without deterioration. Modern electrolytic capacitors can remain usable after lying idle for decades, whereas the original Mershons could not tolerate more than a few months without a polarizing voltage. Elaborate "re-forming" procedures were necessary to avoid damage to receivers that had not been used for some tim

: History of the transistor

Assorted discrete transistors. Packages in order from top to bottom: TO-3, TO-126, TO-92, SOT-23

A transistor is a semiconductor device used to amplify and switch electronic signals. It is made of a solid piece of semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminals. Because the controlled (output) power can be much more than the controlling (input) power, the transistor provides amplification of a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.

The transistor is the fundamental building block of modern electronic devices, and its presence is ubiquitous in modern electronic systems. Following its release in the early 1950s the transistor revolutionised the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, amongst other things.
Main article: History of the transistor

A replica of the first working transistor.

Physicist Julius Edgar Lilienfeld filed the first patent for a transistor in Canada in 1925, describing a device similar to a Field Effect Transistor or "FET".[1] However, Lilienfeld did not publish any research articles about his devices,[citation needed] nor did his patent cite any examples of devices actually constructed. In 1934, German inventor Oskar Heil patented a similar device.[2]

In 1947, John Bardeen and Walter Brattain at AT&T's Bell Labs in the United States observed that when electrical contacts were applied to a crystal of germanium, the output power was larger than the input. Solid State Physics Group leader William Shockley saw the potential in this, and over the next few months worked to greatly expand the knowledge of semiconductors, and thus could be described as the "father of the transistor". The term was coined by John R. Pierce.[3] According to physicist/historian Robert Arns, legal papers from the Bell Labs patent show that William Shockley and Gerald Pearson had built operational versions from Lilienfeld's patents, yet they never referenced this work in any of their later research papers or historical articles.[4]

The name 'transistor' is a portmanteau of the term 'transfer resistor'.[5]

The first silicon transistor was produced by Texas Instruments in 1954.[6] This was the work of Gordon Teal, an expert in growing crystals of high purity, who had previously worked at Bell Labs.[7] The first MOS transistor actually built was by Kahng and Atalla at Bell Labs in 1960.[8]

Printed circuit board (p.c.b)

(Part of a 1983 Sinclair ZX Spectrum computer board; a populated PCB, showing the conductive traces, vias (the through-hole paths to the other surface), and some mounted electrical components)

A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board (PWB) or etched wiring board. A PCB populated with electronic components is a printed circuit assembly (PCA), also known as a printed circuit board assembly (PCBA).


PCBs are inexpensive, and can be highly reliable. They require much more layout effort and higher initial cost than either wire-wrapped or point-to-point constructed circuits, but are much cheaper and faster for high-volume production. Much of the electronics industry's PCB design, assembly, and quality control needs are set by standards that are published by the IPC organization



History

The inventor of the printed circuit was the Austrian engineer Paul Eisler (1907–1995) who, while working in England, made one circa 1936 as part of a radio set. Around 1943 the USA began to use the technology on a large scale to make rugged radios for use in World War II. After the war, in 1948, the USA released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the Auto-Sembly process was developed by the United States Army.


Before printed circuits (and for a while after their invention), point-to-point construction was used. For prototypes, or small production runs, wire wrap or turret board can be more efficient. Predating the printed circuit invention, and similar in spirit, was John Sargrove's 1936-1947 Electronic Circuit Making Equipment (ECME) which sprayed metal onto a Bakelite plastic board. The ECME could produce 3 radios per minute.


Originally, every electronic component had wire leads, and the PCB had holes drilled for each wire of each component. The components' leads were then passed through the holes and soldered to the PCB trace. This method of assembly is called through-hole construction. In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the Auto-Sembly process in which component leads were inserted into a copper foil interconnection pattern and dip soldered. With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are wasteful since drilling holes is expensive and the protruding wires are merely cut off.


In recent years, the use of surface mount parts has gained popularity as the demand for smaller electronics packaging and greater functionality has grown.