Quote:
Originally Posted by daviddeakin
... If you want to survive sustained shorts then add a 100mA fuse ...
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Stating the obvious probably, but I'll mention it anyway. A 100mA fuse will be resistive enough to drop several volts when running at its rated current. So put it before the regulator. And have a think about its rated voltage. Almost all the ones we can source easily and cheaply are rated for 250 VAC. Depending on your raw supply voltage that might or might not be high enough to break reliably.
I speak from experience. I once worked on a large power amp (150 W/ch) which had an HT voltage of ~580V if I remember rightly. The manufacturer had very properly fitted an HT fuse rated for a higher voltage than this. It was about the size of the last two joints of my little finger and each one cost more than a fiver. The fault that the amp came in with, of course, caused it to blow these fuses. To try to keep costs under control I temporarily replaced the fuseholder with a 0.25" x 1.25" open one and fitted a glass-bodied fuse. The first one failed explosively (very exciting !). So I boxed the assembly to catch the flying glass. After a few had gone bang one tracked, allowing the fault current to continue flowing via an arc on the inside of the glass which this time hadn't shattered. "Every day's a school day" as they say.
Cheers,
GJ