On Fri, 2009-09-11 at 11:32 -0400, solarwind wrote: > On Fri, Sep 11, 2009 at 6:28 AM, peter green wrote: > > It is generally a twisted pair but typically not a particulally tightly > > twisted one. Some older phone wiring and a lot of cheap extentions are > > not twisted > > I thought that in a twisted pair line, the pair would carry the signal > and a third wire is required for ground. How does twisted pair > signalling work with only two wires? google: current loop No ground needed. TTYL -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist