What are some examples of circuit simulations with self-managing surges?

[Vinyasi]

I spend a lot of my time simulating circuits whose salient feature is their tendency to surge. I like all surges, but especially those which have any potential to be managed...
http://is.gd/constcurr

The non-manageable ones tend to blow up very suddenly...
http://is.gd/kaboomopamp

My favorite ones are those which are self-managing as an ongoing self-induced oscillation...
http://is.gd/portablebatterycharger

 

[Greg Bernhardt]

Welcome to PF! Cool circuits!