Richard Prosser wrote:
> Or:
> 
>  5V Wallwart -> 470ohm resistor -> cable -> opto -> PIC.
> 
> I don't see what the constant current source is going to give you with
> an ~constant cable resistance of up to a couple hundred ohms.

Not disagreeing with your statement, but the opto-isolators might save 
his bacon.

Now that he's mentioned this is a radio tower site, the requirement to 
deal with lightning hitting the tower and equipment just came into 
play... in my mind, anyway.

Nate
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