DPDT Switch - Insight

DPDT stands for Double Pole Double Throw switch. By using this we can change the polarity of the applied voltage. It is used in situations where we need different outputs. It has 3 states ON, OFF, ON. The difference between the two ON states is that the polarity of both the states is opposite with respect to each other. That’s the reason why it can drive a DC motor in both the directions. It can also switch an AC motor but it can’t change the direction of the motor. Since, AC motor will run in the same direction irrespective of the polarity therefore, it can only be used for switching ON and OFF an AC motor but not for changing its direction.

 

 

Above image shows a diagrammatic representation of DPDT switch.

 

 

Let’s take a closer look into the DPDT switch. The switch as a whole is enclosed in a metallic case as shown below.

 

There are 3 holes in the metallic case. These holes are used to hold the switch in a particular state. This is done by using a ball bearing and spring which is explained later. The state of the switch is changed by a slider whose image is shown below.

 

 

There is ball bearing coming out of the slider. This ball bearing along with the spring, which pushes it outwards fits itself into the holes of the metallic case.  So, by using them the switch attains different states. Hence, the ball remains in three different holes corresponding to three different states.

 

There are 8 pins provided in this DPDT switch. These 8 pins are engraved in a board like structure. These pins are connected inside to metallic plate like structure. These plates connection in different configurations results in change in the polarity. These 8 pins are engraved in the board which is shown below.

 

 

Inside this board these pins are connected to a thin metallic plate like structure. These plate like structures when connected to each other in different configuration changes the polarity. The image of these plates is shown below.

 

When the slider is moved from outside different connections of these plates are formed. The connections are formed by connecting these plates . For making different connections sliding clips are used which are shown below.

 

 

 

Image indicating how clips are used to make contacts between plates.

 

These clips are fitted into the space provided in the slider. These clips, when slide over the metallic plates, result in different configurations. These different configurations give different polarity.

Google open-sources LevelDB, a non-relational database

Non-relational databases are seeing a lot of interest these days as alternative to relational / SQL-based databases. While they are not exact equivalents, not replacements, non-relational databases are simply better suited for certain kinds of data, and today there is a plethora of options for those looking for a NoSQL solution. Google has just added yet another to this field.

LevelDB is a key-value storage engine written in C++, and its source code has now been released under a BSD-style license. Google designed LevelDB as a building block for a higher-level storage system, and it will in fact form the basis for the IndexedDB API – a new web standard for using apps that need a database – in future versions of Google Chrome.

Unlike MySQL or even non-relational databases such as MongoDB and CouchDB, LevelDB is not a server that multiple clients can connect to and operate remotely or even locally. It is a library included in your application to give it support for LevelDB as a data store, similar to SQLite.

You can find out more about LevelDB, and also download its source code from its project page on Google Code.

Anonymous says hacked U.S. government cyber supplier

WASHINGTON (Reuters) - Hackers with the loose-knit group Anonymous said on Friday they had broken into the network of U.S. government contractor Mantech International Corp and posted some NATO-related correspondence online.

Anonymous, tweeting as AnonymousIRC, offered the correspondence between Mantech and the North Atlantic Treaty Organization as proof of the breach. Two involve NATO contracting offices, and one discusses deploying staffers to an unnamed "NATO Theater of Operations" for what appears to be tech services.

Mantech, which claims the U.S. Defense, State and Justice Departments among its clients, declined to comment. It offers cyber security among its services.

Hackers associated with Lulz Security and Anonymous have claimed responsibility for cyber attacks on the U.S. Central Intelligence Agency, the U.S. Senate, Sony Corp websites and the website of Murdoch's British newspaper group, News International, among others.

Authorities made some arrests in connection with the breaches, including a teenager detained at a house in the remote Shetland Islands, off Scotland's northeast coast.

There have also been other arrests in Britain and in the United States.

The group has urged supporters to boycott eBay Inc's PayPal electronic payment service, or to close existing accounts. It has previously attacked PayPal to show opposition to the service's refusal to process payments to WikiLeaks, the website founded by Julian Assange that published copies of secret U.S. government diplomatic cables.

(Reporting by Diane Bartz; Editing by Gary Hill)

Study: dumb people use Internet Explorer

Here comes the flame war. According to a new report, dumb people are more likely to useInternet Explorer than smart people. It's a finding so apparently defamatory that the company responsible for the statement is allegedly being threatened with a lawsuit by inflamed Internet Explorer aficionados.

Online psychometric testing company AptiQuant, based out of Canada, turned its analytical skills to a group of more than 100,000 individuals in an effort to determine the IQ scores associated with various Web browser users. Over a period of around four weeks, the company gave a Wechsler Adult Intelligence Scale (WAIS) to users looking for free online IQ assessment tests, then recorded the results and browsers used for all participants above the age of 16.

AptiQuant's report notes that the only statistically significant difference in IQ scores occurred between Internet Explorer uses and their counterparts. There was not a significant difference in IQ scores between non-IE browser users, even though these users, in aggregate, reported a higher average IQ score than IE users.

Across the board, the average IQ scores presented for users of Internet Explorer versions 6 through 9 were all lower than the IQ scores recorded for Firefox, Chrome, Safari, Camino, and Opera users. Humorously enough, those using Internet Explorer with the Chrome frame built-in actually ranked third in IQ scores among this browser list. Opera users reported the highest average IQ score – hovering around the 120 to 130 range, which is a bit higher than the WAIS test's population mean of 100 (and standard deviation of 15).

"In addition, the results were compared to another unreleased study of a similar nature undertaken in year 2006. The comparison clearly suggests that more people on the higher side of IQ scale have moved away from Internet Explorer in the last 5 years," reads the report.

Although AptiQuant does get a little heavy-handed against Internet Explorer in its report, suggesting that the "nuisance" browser should be "eradicated," the company has been quick to note that its findings only indicate a one-way relationship between IQ scores and browser use. Perhaps, in part, prompted by alleged threats of a lawsuit against the company by upset Internet Explorer fans.

"I just want to make it clear that the report released by my company did not suggest that if you use IE that means you have a low IQ, but what it really says is that if you have a low IQ then there are high chances that you use Internet Explorer," said CEO Leonard Howard.

Copyright © 2010 Ziff Davis Publishing Holdings Inc.

Source: Study: Dumb People Use Internet Explorer