An EDN Design Idea - Originally published in the May 29, 1986, issue of EDN
Mark D Braunstein, Contel Information Systems, Fairfax, VA; Edited by Paul Rako and Fran Granville - January 19, 2012
Using the system shown in below, you can quickly test a cable containing twisted-wire pairs and detect open or reversed pairs, shorted pairs, and shorts between unrelated pairs. The tester consists of an active test set that plugs into one end of the cable, and a passive terminator that plugs into the other end. (An RS-449 cable is used as an example.)
Looking at this in a little more detail, it will work well to detect opens, shorts and pairs connected backwards are one end. It will not detected pairs connected out of order...say pair 1 at one end connects to pair 4 at the other. Therefore, it's not effective to detect RJ-45 cross-over cables...
Maybe we can do better?
Re: Simple Circuit Tests Twisted-Pair Cables - Try 2
6 years 6 months ago #12874
Why not use the bi-directional red/green LEDs (two pin, connected in opposite directions, you know the ones) for the terminator end? Green = good, off = open / short, and Red = connected backwards. Better diagnostics then