On 5/13/05, Francois Robbertze <fr10@mweb.co.za> wrote:
> I want to test a 2km (1.6mm dia) steel wire that runs around a residential
> home for continuity.

  My honest suggestion: forget about it. There aren't any protective
devices against lighting without damaging your PIC, even with 7.5KV
optoisolators on inputs. You need at least 25KV real optoisolation
(home made or industrial air barrier optocoupler) .
Now Texas has moved in the Europe.
You need a laser protected perimeter, and if it's only for caws, then
maybe will be to expensive, it require acumulators, radios and laser
beams.

best regards,
Vasile



> 
> There are several wires parralel to each other, but aren't connected
> together. All the wires are tightened to wooden poles - no isolators.
> 
> I was thinking of connecting a 12V power supply on the one end. The other
> end I want to connect to one of the PIC's pins. (through voltage devider or
> what ever...)
> 
> It must use relatively little current (powered by a 12V battery) and must be
> robust agains lightning.
> 
> Can someone help me with connections.
> 
> Must I use optocouplers, MOV's or Transorps
> 
> Regards
> 
> Francois
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