Changing a Light to a 3 Way

I have a light at the bottom of a staircase with a single switch at the top of the stairs. I want to make this a 3 way setup, adding a second switch at the bottom of the steps.
The current switch has only 2 wires going to it so I'd assume that the power is going directly to the light.
Can someone provide a wiring diagram for converting this to a 3 way. Thanks.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
JAG wrote:

http://home.howstuffworks.com/three-way2.htm
--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You can't do it without either replacing the cable from the fixture to the
existing switch to something with 3 conductors (plus ground) or converting the switch wiring to a signal circut and using a relay.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
JAG wrote:

Here's an alternative to rewiring. There may be others.
http://www.homecontrols.com/cgi-bin/main/co_disp/displ/prrfnbr/3198/sesent/00
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.