Timers such as 555 are in many cases essential to modifying electronics and creating DIY synths. Just recently I’ve began using 556s which are two 555 timers in one IC. And then I learned about QUAD timer IC ( NE558 ) . Four oscillators in one convinient IC! Someone please pinch me! It is a 16 pin package so not all the pins present in a normal 555 are there. At any rate I will definatelly be experimenting with this one very soon.