I've been experimenting with a 2N2222 transistor (in the TO-18 metal case) and using it as an avalanche transistor -- by not connecting the base and having the emitter and collector connected in reverse (so maybe I'm actually using the reverse mode, I'm not really sure)... basically it avalanches and continues being on until current drops to zero, then resets itself undamaged.
I (mistakenly) thought that all X2222 variants would behave the same, such as the BT2222A (an SMD package) that I was about to order.
Now, experimenting with PN2222 (TO-92) and it's not avalanching the same way (if it really is doing so). if it's avalanching, it tops off to a certain voltage (around 9.15V on a 16V supply, with voltage drops on a few other components, of course), then very, very momentarily avalanches just to go slightly under 9.15V, then stops the avalanche. then it repeats the cycle... or at least I think this is what it's doing.
Why is this, and what can I do to make PN2222 behave more like 2N2222?