"If you work with network cables, then a cable tester is an indispensable tool that shouldn't be missing from your toolbox. PC911 shows you how to create a simple but reliable 10Base-T cable tester that will work with any
continuity tester or ohmmeter."
FULL STORY @ PCNINEONEONE (http://www.pcnineoneone.com/howto/cabletester1.html)