LED Cable Locator

[matt95gsr]

Some time ago, a coworker of mine made his own set of LED terminated RJ45s to locate cables. What he did after he pulled all the cable was to load up the patch panel with the LED's and then on the station end he plugged in a little box powered by a 9V battery. The corresponding port on the patch panel then lit up and made for super-quick work of labeling the drops. Pretty simple idea, I just remember that the 9V box had a few resistors and stuff in it, but I can't remember the details. Can anyone clue me in on the proper way to make one of these homebuilt models? Thanks.

 

[jerryreeve]

I would think that the item at the patch panel would be a two way LED across pins 4 and 5 so that voltage either way would cause the LED to glow. the box would be a 9V battery and a diode that would only allow about 6 volts to pass..so the diodes don't blow. I'll have to dig to see what partnumbers you would want though...unless someone else gets the info to you first.

JerryReeve
Communications Systems Int'l
com-sys.com

 

[qwzx]

We are required to lay our patch cables down in order of their placement in the building. I have used LED's but then had to pre-strip all the cables. The fastest for me is to terminate the station ends and then tone the cables at the patch panel in order. I use a "fox and hound". It amounts to a little oscilator with a rj45 plugged into the station end and a high impedence amp with a probe at the patch panel. The "fox and hound" come as a set and costs less than $100. There are several different brands. They each are about the size of a cigarette pack.
BUT If you need to verify that you have not rolled a pair or crossed tip and ring, then the LED route is the cheapest way to go. You would also have to make it polarity sensitive.

 

[EdPorts]

I like the LED route if you don't have to correlate the patch panel to the wall plates or jacks...

Of course IDEAL makes a box that does that. I imagine you could purchase the RJ-45 plugs that they have with the tiny LEDs in them, and then make your own power source -- that would be considerable cheaper, and faster than making each individual plug.

I do recall that there are two different LEDs in the IDEAL variety, green and red, and I believe they're on either different pairs, or if you reverse the polarity it lights up the green instead of the red -- one or the other, there is a small switch on the power source that says green or red... so I'm not sure.

It certainly is faster and easier that way... especially when you're looking at patch panel setup with 100 or more ports.

 

[TouchToneTommy]

We use the Ideal units. The LED is dual color. They are connected to pins 3 and 6. The power unit(s) have a polarity switch that can make them glow red or green. If you have two guys running around, one sets his unit to red, the other to green. The poor guy at the patchpanel works twice as hard. Since we split our kit into two, so we could cover two trucks, I will use my toner, set on talk battery, and connect it to "line 2" on my modular adapter. The toner has enough internal resistance not to blow the LED. This way I can use my toner to send "red" and the Ideal power unit to send "green". Working alone I can send two different jacks, go ID them at the patch panel, swap dongles for the LEDs, go back to the jack to label and test, and then move on to the next jack location.

 

[PhoneGuy2000]

I have a novel idea... Label the cables before you pull them. I suggest using write on self laminating labels so the writing is easier to read and won't smear. Mark your prints, label the cables, pull them, label each one, one at a time and THEN cut them. Next, you can dress them according to number and terminate in order.

If you really want to move up in the world, read the EIA/TIA 606 labelling standard for structured wiring.

 

[matt95gsr]

Thanks for the info guys...And as for people that want to think I'm a moron, I'm well aware of how much easier life is if things are labeled early on, but maybe the next time you're stuck looking at 500+ unlabeled jacks that someone else left you responsible for someone will act like they're better than you when you ask for an idea. So, thanks PhoneGuy2000, and I'm well aware of all the EIA/TIA (not that you know what that stands for) spec, and can probably quote pages from the BICSI manuals in my sleep (see, I know industry buzzwords too!), but go crap on someone else's post if all you can do is criticize someone.

Thanks a lot to everyone else who contributed, though.

 

[jerryreeve]

matt95gsr, I'll have to agree with you on the headaches of inheriting a cabling setup that someone else started. another winner is the customer who moves out and pulls all the patch panels and just leaves the cables dangling from the ceiling.

the circuit you were asking about is a 9V battery with a voltage regulator across it, the third leg of the regulator is a regulated voltage that is less than 9 volts and that is what would go to your alligator clips/bed-of-nails clips to be connected to pair 2 of the cable you use. then put in a bi-directionsl LED in the rj-45 plug on pair 2 and then whichever direction current flows you would get an indicator. (the voltage regulator needs to be matched to the LED because I have burned out a few LED's with straight 9V.

JerryReeve
Communications Systems Int'l
com-sys.com

 

[matt95gsr]

Thanks a lot Jerry, that's the info I was looking for.

 

[PhoneGuy2000]

As a matter of fact, to earn the designation as an RCDD, I had to pass a proficiency test that included the 606 standard. And no I don't think I am better than anyone, I made a comment based on a post stating that as a practice the cables were being pulled unlabelled and identified later. It did not say anything about inheritting a mess as you suggest. This forum is not for insulting people and that is not what I was doing. It also seems that the practice of pulling cables without labelling is wide spread. Many of the people reading might appreciate how smooth an install goes and how easy it is to dress the cables in if they are labelled up front. Especially when you are given a job that has the cable numbers already listed on the prints.

Larry McNeill, RCDD, Registered Technician

 

[Grenage]

It's very easy to take things the wrong way with emotion-les text isn't it