Robert Nansel wrote: > >Hi All > >My PIC based alarm system has been blown up with a High Voltage > >zapper; those handheld units for shocking people/animals... > >Apparently this is a new craze among burgulars. Thy kill home alarms, > >car alarms and cct video with these zappers. > > > >Short of using screen cable for every sensor, is there other devices > >or goodies that can protect alarm systems from this assault???? > > > >Regards > >Cassie > > Yikes! And I thought I'd heard everything! What do those zappers put out? > Several kilovolts, I'm sure. > Can't be too high - it would kill humans if things get that wild. Besides they run off 'D' cell batts (usually). Although around here the burglars will probably borrow their taxi's battery to do the job.... :(. > By "screen cable" do you mean shielded cable? I have doubts how effective > plain shielded cable would be against this type of attack. > Don't think so either - if the HV is running down the one of the cores connected to the sensor.... Unless its merely to protect against the discharge of these zappers. That could be considered extremely large noise. > Hmmm...I'm not sure what could be done about this except to use either > fiber optics for any cable runs or optoisolation on the controller board, > though 5300 KV seems to be tops for cheap optoisolators. If the zappers > produce more than this, you're sunk. See above. These things will (my reasoning) not produce more than 15kV. Few milliamps too.They are commonly used to remove drunks from private property and to break into houses... aagh! i get it... Else we can wait for MChip to patent and develope a "Brown-UP" circuit... -- Eric van Es | Cape Town, South Africa mailto:vanes@ilink.nis.za | http://www.nis.za/~vanes LOOKING FOR TEMPORARY / HOLIDAY ACCOMODATION? http://www.nis.za/~vanes/accom.htm