[VLM]

"(either missing a heat sink, or too much voltage drop across, or the circuit needs something more powerful)"

Starting in the 80s Low Drop Out LDO regs started hitting the market, using mosfets as the pass transistor instead of bipolar trans (and a few other changes) means you can run with much lower voltage drops.

However, legendarily, the bipolar voltage drop automagically provided some oscillation dampening and the LDO regs are notorious for being unstable, almost as much of a PITA as using a switching reg, almost. So sometimes with reactive (usually inductive) load at certain currents and voltages, they turn into little RF oscillators. Sometimes the oscillation is too high of a freq to interest the overheating and other self protection ckts so they literally catch fire and so on.

These 80s stereotypes of LDO regs have been continually improved since the 80s so they're somewhat more stable now.

Part of the shocker of both the bad 7805s in the story and the oscillating 80s era LDOs is the 7805 series used to be legendarily bulletproof because they have a lot of self protection circuitry built in. Blowing one up is non-trivial compared to most other chips. Usually decent reverse current protection, some reverse polarity protection, overheating protection, short ckt protection, they're pretty touch chips, so its surprising when they aren't.

[raverbashing]

Ah very interesting story, I didn't know about those LDO problems.

I guess BJTs at that power level are slow, as opposed to mosfets, which are much faster, so there's that as well.