This is what I came to point out. The 555 is a horrible waste of electronics for something as simple as an oscillator. (Also, iirc, 555 timers do nasty things t

This is what I came to point out. The 555 is a horrible waste of electronics for something as simple as an oscillator. (Also, iirc, 555 timers do nasty things to your rails.) You can get a better (50% duty cycle) out of a comparator/op-amp, a capacitor, and a few resistors. http://en.wikipedia.org/wiki/Relaxation_oscillator#Op_Amp.E2.80.93based_electronic_relaxation_oscillator http://en.wikipedia.org/wiki/Relaxation_oscillator#Op_Amp.E2... 555 timers are much more useful as one-shots, since that functionality is much more difficult to implement with a comparator.