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555 timer IC NE555 from Signetics in dual-in-line package Type Active , Integrated circuit Invented Hans Camenzind First production 1971 Pin configuration GND, TRIG, OUT, RESET, CTRL, THR, DIS, VCC Electronic symbol Internal block diagram The 555 timer IC is an integrated circuit (chip) used in a variety of timer , pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator , and as a flip-flop element . Derivatives provide up to four timing circuits in one package. Introduced in 1971 by American company Signetics , the 555 is still in widespread use due to its low price, ease of use, and stability. It is now made by many companies in the original bipolar and also in low-power CMOS types. As of 2003, it was estimated that 1 billion units are manufactured every year. [ 1 ] Contents 1 Design 1.1 Pins 1.2 Modes 1.2.1 Bistable 1.2.2 Monostable 1.2.3 Astable 2 Specif

Timer Kitchen timer A timer is a specialized type of clock for measuring time intervals. [ 1 ] By function timers can be categorized to two main types. A timer which counts upwards from zero for measuring elapsed time is often called a stopwatch ; a device which counts down from a specified time interval is more usually called a timer [ 1 ] or a countdown timer. A simple example for this type is an hourglass . By working method timers have two main groups: Hardware and Software timers. Some timers sound an audible indication that the time interval has expired. Time switches , timing mechanisms which activate a switch, are sometimes also called "timers". Contents 1 Hardware timers 1.1 Mechanical timers 1.2 Electromechanical timers 1.3 Electronic timers 2 Software timers 2.1 Software applications 2.2 Other types 3 See also 4 References 5 External links Hardware timers Mechanical timers A typica

Stuxnet is a malicious computer worm believed to be a jointly built American - Israeli cyber weapon . [ 1 ] Although neither state has confirmed this openly, [ 2 ] anonymous US officials speaking to the Washington Post claimed the worm was developed during the administration of Barack Obama to sabotage Iran’s nuclear program with what would seem like a long series of unfortunate accidents. [ 3 ] Stuxnet specifically targets PLCs , which allow the automation of electromechanical processes such as those used to control machinery on factory assembly lines, amusement rides, or centrifuges for separating nuclear material. Exploiting four zero-day flaws , [ 4 ] Stuxnet functions by targeting machines using the Microsoft Windows operating system and networks, then seeking out Siemens Step7 software. Stuxnet reportedly compromised Iranian PLCs, collecting information on industrial systems and causing the fast-spinning centrifuges to tear themselves apart. [ 5 ] Stuxnet’s