The first 555 timers, the NE555V/SE555T from Signetics ... Perhaps the most common use is as an astable multivibrator or RC relaxation oscillator. In this role, an external resistor and capacitor ...

The 555 timer is used as a free running oscillator. We know that this not be very stable when compared to even the worst of crystal oscillators, but that’s what makes it work so well as a random ...