NE555 Precision Timers

DescriptionNE555 are precision timing circuits capable of producing accurate time delays or oscillation. In the time-delay or mono-stable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the a-stable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor.Datasheet:http://www.ti.com/lit/ds/symlink/ne555.pdf