[Lowfer] Optic Isolator?

[Bill Ashlock]

Kurt,

>My concern is voltage on the wire as we have several lightning strikes 
> >within a few hundred feet of the house.  Is there some sort of 
>opto->isolator circuit that can be used in this arrangement to protect my 
> >computer?  It only needs to work to roughly 50 KHz.

The opto isolator would require some amplification behind the internal LED 
to be able to act as an isolator in this application. Why not use a ferrite 
coupling transformer to keep the main source of the problem (a high amperage 
surge of current) away from the sound card? You will need a high 
permeability core like #77 to insure there is enough inductance (maybe 10mh) 
on both primary and secondary. Common mode chokes found inside line filters 
are a good source for this type of core.

I also suggest a 10v varistor across the sound card side of the transformer 
to grab the initial spike.

Bill

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