Thanks all for your responses.
jimmo wrote: ↑
Sun Oct 27, 2019 11:22 pm
To the OP: Yep we've all been there! Sorry about your micro:bit
But as a sort of counter point (with apologies to the OP): I'm amazed at just how bulletproof the micro:bits are. I've probably seen close to 1000 micro:bits (a milli:bit?) go through some fairly heavy usage without a single failure. Admittedly we don't give the students access to any higher voltages than 5V...
I'm sure they are very tough, but only, as you suggest, using the built-in 3V output of the micro:bit itself; max output of which is only @ 100mA, I believe. I'm not going to try it, but I reckon even a single AA battery would be enough to fry a micro:bit the way I did it. A fully charged AA can output anywhere between 5 and 10 Amps when short-circuited, 50 to 100 times more than the micro:bit is probably designed to handle.
My recommended improvement would be a 0.1A SMD Resettable Fuse PPTC PolySwitch Self-Recovery Fuse
fitted to most of the pins, a row of them above the edge connector itself. Do any of those add-on shield things give such surge-protection to the edge connector? . . . might be a good product idea.