At 11:24 AM 11/12/97 -0500, you 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.

50,000 to 500,000 volts. Its important to keep in mind the waveform, and
spectrum. Stun impulses are probably in the KHz bandwidth, making sparc
gaps, resistors and capacitors effective.

After you read the Intel AN-125 and zilog stuff, have a look at Microchips
APP note (I forget #) on SCR latchup. If a transient hits your power supply,
it could cause this type of fault to your PIC and other CMOS chips. It will
take extra harware to deal with.

If somebody realy is mad at you, see a tutorial on EMP bombs on Winn
Schwartau's infowar site (www.infowar.com?). You may have to go back to
using vacuum tubes ;)