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,=20 >and then relying on the supply over current protection to limit the=20 >current, or mains protection fuse to blow. A SCR-type crowbar is exactly what I'm looking for. Actually, I'm=20 looking for a pair of them in one package that accepts a standard=20 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=20 of power supply failures, so I completely understand where this fella=20 is coming from. Both of the failures in my systems were that the=20 power supply went significantly over-voltage. Something on each=20 motherboard died - the hard drives were readable in another system. Regardless, if those power supplies had internal over-voltage=20 protection, it didn't work. A solid crowbar across the rails is exactly what I want. If that=20 causes smoke to emanate from the power supply, so be it. I'd rather=20 see the person replace a $150 power supply instead of both power=20 supply *and* several thousand dollars of expensive, high-end computer hardw= are. I can build something but I'd much rather purchase the two or three=20 units that I need. Many thanks! dwayne --=20 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 --=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 .