The 555 timer is arguably the most famous integrated circuit ever invented. Created by Hans Camenzind in 1971 for Signetics (now NXP), the 555 timer is still widely used and in production. These devices are so common that over 1 billion are made each year. But what makes the 555 timer so useful? Why is this tiny little 8 pin device still be mass produced despite being over 40 years old? In this kit you will be making a 555 astable circuit which is one of the most common uses for this chip.