fun circuit I discovered while reading this site, referring to the section on Shockley diodes.
http://www.dos4ever.com/ring/ring.html
When the supply voltage becomes high enough to break down one of the pn junctions, the diode will avalanche and switch on. since Shockley diodes are no longer produced he shows some similar circuits using general purpose transistors.
unfortunately EC transistors don't have a breakdown forward voltage in simulation. so here's a hysteresis latch instead.
