1. 555 Timer
Integrated Circuit

2. Integrated Circuits
The 555 Timer is an Integrated circuit. IC’s are premade circuits that consist of many resistors, transistors and diodes. These components are then miniaturized and manufactured to fit on a single silicon chip. These circuits can contain thousands of transistors, and are what give modern computing portability. IC chips are the brains of our computers and can maintain and control a circuit based on a simple set of instructions.

3. Circuit Symbol
The 555, like all IC’s is characterized in a circuit diagram by a rectangle with labeled connections (ie the pinout of the IC). The order and placement of the pins may vary in the diagram and may not be in the same order as they appear on the actual chip itself. The +Vs and 0V refer to the positive and negative leads of the chip. This supplies the current required to operate the IC. Other pins serve as input output and control functions.

4. Programming the 555
Some chips are programmable using an interface such as a computer. The 555 uses an arrangement of calculated resistances and capacitances to perform the desired output. The output pin is either High or low. The trigger pin starts the timer when it is below one third of the input voltage. The discharge pin discharges an external capacitor that works in with a resistor to control the timing interval .for Generally the timer runs on the standard 5v or 3.3v. The 555 is one of the most common IC chips in the world and can be useful for any device.
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5. Works cited
Mims, Forrest. Getting Started in Electronics. Vol. 7. Estados Unidos: S.n., Print.
"Best of 555 Timer Application Circuits Explained." Brighthub Engineering. N.p., n.d. Web. 28 Mar < 555-explained/>.