[Lowfer] Optic Isolator?

[KD7JYK]

I read an article from http://www.vlf.it/trond2/softreceiver.html today
about a "Soft" LowFer receiver.  The idea is to use a spectrum program and
plug the antenna directly into a sound card input.  My concearn is voltage
on the wire as we have several lightning stikes 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.

Is there an equivelent to "Spectrogram" software than runs under Windows
3.11??

Kurt

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