Re: Extending the range of null modem to 100ft.

[russotto@grace.speakeasy.net (Matthew Russotto)]

In article <ChMOd.6302$m31.75824@typhoon.sonic.net>,
Andy McFadden  <fadden@fadden.com> wrote:
>
>For this to work, one or both modems must be supplying current on the
>phone line.  Some of the telco devices I've worked with have used an
>optical component (can't think of the part name now) to electrically
>isolate the analog and digital components.  As with common household
>phones, these didn't supply power.

Optoisolator. Cheap consumer modems don't use them.  Actually very few
modems use them... there were a few, though (Racal-Vadic, I think).