Just a quick word of warning - I've also lost a motherboard due to power supply failure. Actually it was the dreaded electrolytic capacitor failure mode. Trouble was it was the caps on the motherboard itself, in the 5V-3V3 or 1V8 or whatever that failed. So your protection may not be in the right place. It took out the ram, southbridge? and probably a few other bits & pieces also. (the CPU survived) RP On 13 November 2015 at 06:59, Dwayne Reid wrote: > At 03:09 AM 11/12/2015, alan.b.pearce@stfc.ac.uk wrote: >> > Is a relay closure/opening fast enough for your application? >> >>Normally it is done by an SCR crowbar shorting the supply output, >>and then relying on the supply over current protection to limit the >>current, or mains protection fuse to blow. > > A SCR-type crowbar is exactly what I'm looking for. Actually, I'm > looking for a pair of them in one package that accepts a standard > 4-pin Molex hard-drive power connector coming from the power supply. > > I've had two different computer systems die in the past year because > of power supply failures, so I completely understand where this fella > is coming from. Both of the failures in my systems were that the > power supply went significantly over-voltage. Something on each > motherboard died - the hard drives were readable in another system. > > Regardless, if those power supplies had internal over-voltage > protection, it didn't work. > > A solid crowbar across the rails is exactly what I want. If that > causes smoke to emanate from the power supply, so be it. I'd rather > see the person replace a $150 power supply instead of both power > supply *and* several thousand dollars of expensive, high-end computer har= dware. > > I can build something but I'd much rather purchase the two or three > units that I need. > > Many thanks! > > dwayne > > -- > Dwayne Reid > Trinity Electronics Systems Ltd Edmonton, AB, CANADA > (780) 489-3199 voice (780) 487-6397 fax > www.trinity-electronics.com > Custom Electronics Design and Manufacturing > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .