''"Taser" extra high voltage shock devices applied to wiring/camera/PIR sensor ... (Real security industry event according to an alarm specialist on this list some while ago)'' A friend of mine, in the interest of science, has performed experiments on these types of systems in the past using a simple car-coil and a D cell battery or two in order to test their vulnerability ... most of them do not fare well after such 'test' sparks ... ''Has the beauty of travelling far and wide on your wiring ... '' As a result, do you avoid even the simplest of protection of your designs - or do you learn from such examples or 'tests' of your designs and using feedback learned from such testing stumble upon the 'proper design'? (e.g. simple spark-gaps to ground, in the same veign as color-tv manufacturers use on their product in order to insure it's survivial) Unless your spec calls for survivability under these kinds of conditions - I doubt most of us even consider the various types of 'protection' that is necerssary in order to insure a design can withstand this type of 'event'. I have had experience with TTL-logic mounted on boards that were attached to a TWT's cathode - boards which possessed a negative potential WELL in excess of -20 KV in order to effect electron emmission (literally, "thermionic emmission") from said cathode for the purpose of setting up a rather healthy electron beam down the center of said TWT amplifier tube. Other circuitry on this board also incldued the TWT grid drive circuitry as well as the filament regulator, assorted BIT (Built In Test) circuitry and of course, the 5V regulator circuitry ... arcs through the tube or in the grid pulse HV isolation transformer or simply through the silicone oil were catastrophic to the logic on the board - there was little protection that could be designed-in given the limited space available and the power involved in any particular arc as sourced by the HV power supply ... The lessons I *did* learn from all this was what *could be* used to couple signals onto and off-of said board 'floating deck' (the 'official' name of this board BTW) WELL in excess of -20 KV ... so I don't think such design goals such as imperviousness to 'taser attacks' are impossible - they JUST need to be specified in the design docs, reflected on the SOW (the statement of work) and mentioned in the final 'quote' ... RF Jim ----- Original Message ----- From: "Russell McMahon" To: Sent: Tuesday, October 22, 2002 12:35 AM Subject: Re: [EE]: Foolproof input line > > - which can get easily get 'spooked' (reset, garbled > > data or even potentially destroyed) by transients > > generated by motors (series wound vacuum motors!) on > > the mains switching on and off or lightning strikes > > (induced or secondary effects occurring as far as a > > 1/2 to a mile away!). > > "Taser" extra high voltage shock devices applied to wiring/camera/PIR sensor > with aim of rendering your security system insensible :-) (Real security > industry event according to an alarm specialist on this list some while > ago). Has the beauty of travelling far and wide on your wiring and very > likely taking out not only interface it is applied to but also the > controller and other interfaced devices. > > > RM > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body