When I was first discovering electronics I would search for any simple project I could get my hands on.  Most of them involved making use of a 555 timer.  What is this IC you may ask?

The following sections offer a brief introduction to one of the most used IC ever produced, the 555 Timer.  The applications of this IC are endless.  A few examples are: timing events, synchronizing signals and as triggers in general.  They are used in anything from intermittent windshield washers to electronic ignitions.  They can be found in toys as well as medical equipment. It is to your advantage to learn the basic configurations used.
 

555 BASICS:
Pinout and Explanation of Monostable and Astable.

MONOSTABLE EXAMPLES:
Explanation of a 555 being used as a Monostable Multivibrator. Schematics and PCB layout for your own use.

ASTABLE EXAMPLES:
Explanation of a 555 being used as an Astable Multivibrator. Schematics and PCB layout for your own use.

555 CALCULATORS:
Figure out those Resistor and capacitor values fast with this Javascript calc.