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Old 29-07-05, 02:10 PM
PV5150 PV5150 is offline
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Guide: Make yourself a simple Cat 5 tester

Hi Guys

Here is the first practical guide as promised, on how to make a Cat 5 cable tester. This project should cost AUS$10.00 max to make, as long as you have the hand tool needed, I have taken the liberty of including the prices I paid for the parts. This project is very simple in design, but should provide a platform for further kits to follow. I hope you enjoy this guide, and learn a little bit from it. Further, I shall also explain some of the theory required and what the main components actually do as we go along.





Warning: Power tools, sharp objects and electrical energy can all be dangerous to your current state of well being, so take care and follow all relevant safety safety precautions - especially eye protection. If you are unsure of such precautions, ask me or seek other professional advice. Any omission regarding possible hazard is not the responsibility of Overclock3d Forum or the writer.

Equipment Required

* Side cutters

* Soldering iron (fine point, butane or electric)

* Solder (with flux core, recommended size 0.71mm)

* Multimeter

* 3mm copper core wire

* Electrical tape

* Dremel or hacksaw

* Drill or dremel with 3mm drill bit.

* 1 x Black or clear UB5 (83 x 54 x 31 mm or close to that) jiffy box AUS$2.50

* 2 x RJ45 8P/8C PCB modular sockets AUS$1.70 each

* 8 x 2.1V, 15mA 3mm Red LED's (or whatever colour you like) AUS$0.20 each

* 1 x AA Battery holder AUS$0.80

* 8 x 1/2W resistors. AUS$0.38 a pack of 8

* 2 x 1.5V AA batteries (2 x 1.5V = 3V)



You will notice a rectangular shaped white object in the left hand corner of the picture above, this is just another version of an LED, just in a bar graph format. You are more than welcome to use that one if you like, but you will need to purchase some bigger resistors. I actually don't know the rating of the LED bar Graph module, but I expect 100W resistors should allow for it to be plenty bright enough, without popping it by giving it too much juice.

A little about LED's and resistors



LED's

LEDs emit light when an electric current passes through them.

LEDs must be connected the correct way round, the diagram may be labelled a or + for anode and k or - for cathode (yes, it really is k, not c, for cathode!). The cathode is the short lead and there may be a slight flat on the body of round LEDs. If you can see inside the LED the cathode is the larger electrode (but this is not an official identification method).

LEDs can be damaged by heat when soldering, but the risk is small unless you are very slow. No special precautions are needed for soldering most LEDs.

Testing an LED

Never connect an LED directly to a battery or power supply!

It will be destroyed almost instantly because too much current will pass through and burn it out.

LEDs must have a resistor in series to limit the current to a safe value, for quick testing purposes a 1kohm resistor is suitable for most LEDs if your supply voltage is 12V or less. Remember to connect the LED the correct way round!

Resistors



Resistors restrict the flow of electric current, for example a resistor is placed in series with a light-emitting diode (LED) to limit the current passing through the LED. Resistors may be connected either way round. They are not damaged by heat when soldering.

The Resistor Colour Code and Colour Number

Black

0

Brown

1

Red

2

Orange

3

Yellow

4

Green

5

Blue

6

Violet

7

Grey

8

White

9

Resistor values - the resistor colour code

Resistance is measured in ohms, the symbol for ohm is an omega ohm.

1 ohm is quite small so resistor values are often given in kohm and Mohm.

1 kohm = 1000 ohm 1 Mohm = 1000000 ohm.

Resistor values are normally shown using coloured bands.

Each colour represents a number as shown in the table.

Most resistors have 4 bands:

* The first band gives the first digit.

* The second band gives the second digit.

* The third band indicates the number of zeros.

* The fourth band is used to shows the tolerance (precision) of the resistor, this may be ignored for almost all circuits.

The Problem

The job of a network cable is to allow packets of data to travel effieciently between two points, and arrive intact. Network failure typically occurs because of damaged cables; connecting plugs; dodgey hubs; transmission losses (line noise) or damaged/incorrectly setup PC drivers. This project will deal with only the first situation, the rest is up to you!!!

A damaged cable (or plug/socket) refers to a physical break in a transmission wire somewhere along the cables length (called an 'open circuit') . The break means that the electrical signals can't get through and your PC will drop out of the network (error: signal lost).

The Solution

To test for a break in a wire we can do a continuity test. The simplest form of this is a light globe and a battery. If the length of wire under test is unbroken then the globe will light up. If the wire has an internal fracture the globe stays off. Easy so far isn't it?



In the above picture we have a single globe and therefore we are only able to test one wire at a time. Cat 5 (and Gigabit Cat 6) LAN cables have eight wires so we'll design a parallel circuit to test all eight wires simultaneously. And we won't bother using expensive, inefficient globes - we're gonna use LED's.

As I mentioned before, LED's need a current limiting resistor or else they'll fry from excess of current. To find a suitable current limiting resistor we need to use Ohm's Law V = I x R where V is the excess voltage across the resistor, I is the desired current in Amps, and R is the required resistor value in Ohms.

As we need to find the resistance, we need to rearrange the equation to be R = V / I. Don't forget that 15mA is entered into the equation as 0.015 and not 15. We have eight parallel loops so we only need to work through the equation once (all eight LED's will have identical currents).

Now for some more Maths (I can hear the groans in the background lol) R = (Supply Voltage - LED Voltage Rating) / Desired Current (in Amps)

R = 3V - 2.1V / 0.015A = 60

But nobody sells 60 Ohm resistors, I couldn't find any anyway lol. The closest standard size is 62 Ohm.

Building the box

This is a simple parallel circuit we need to build. One end of the LAN cable is connected directly to the battery (all eight wires combined together), while the other end of the LAN cable gets connected to each LED and resistor. Be aware that the LAN plug going into the left hand side of the circuit will correctly align with the LED's (i.e. the top brown wire will light up LED 1, etc)

Step 1.

The openings for the LAN sockets should be 14mm high by 15mm wide. Use a hacksaw or the dremel to cut these openings. If you place the opening at about 10mm from the edge of the jiffy box then the internal leg will push against the socket, wedging it in place. Try to cut the hole as tight as possible, as gluing it in will more than likely crack. There are lugs on the side of the RJ45 plug that will help hold it in position, as well as then lid being screwed on.



Step 2.

Drill a neat, vertical row of 3mm holes for the LED's to sit in. Use superglue for LED mounting. When drilling the holes for the LED's, flip the jiffy box lid over and there are 'blind pilot' holes to help evenly distribute and accurately line them up. When installing the LED's, you can either pass the head through the underside and glue in, or alternatively, pass the LED through the top and glue the underside of the cone to the top of the lid. Make sure that all the short legs and long legs of the LED's are on the same side as each other, and that they aren't touching to prevent short circuits.



Step 3.

The positive power lead from the battery pack is directly soldered to the positive LAN socket and has all of its pins soldered together.



On each of the positive 'anodes' of each LED, you need to solder on a resistor. Be sure that your soldering iron is really hot, otherwise you may get a dry solder joint as a result, or the solder may not run effectively. Start by putting dabs of solder on each of the LED legs, keep the resistor legs uncut and place the soldering iron under the LED leg to heat the solder. You should find that the leg of the resistor will now be soldered to the LED. Do this for all the LED's.

Next, attach the resistor legs to the other LAN socket. You must keep the LED's and LAN wires in order. The 'top most' LED gets soldered to the top most LAN terminal, etc. In order to prevent risk of short circuit, you may run electrical tape around the bare, exposed wires as I have done in the picture below.



Step 4.

The other end of the LED's (negative legs) should all be soldered together, be careful not to put too much pressure on the legs as you tie them together . Join them to the negative battery lead with solder, and you're done!!!



Install all the parts neatly into the jiffy box, place in your batteries, screw the lid on, plug in a LAN cable and test to your hearts content.





Pointers

Before sealing the box check for loose wires that can cause shorts. With a new set of batteries the unit is ready to go. You will see that plugging in a LAN cable completes the circuit and makes the LED's glow (fingers crossed). This means that we don't need an On/Off switch either. You now have a sturdy/cheap LAN tester to help at all those seedy LAN parties you attend, and it's a sure fire way to attract the opposite sex.

A big "Thank You" goes out to Jock, for lending assistance and his wealth of knowledge

P.S Sorry some of the pics seem a little blurry, I was trying to give as much detail in the pic as possible. It didn't happen!!! But you get the idea, I hope.

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  #2  
Old 29-07-05, 02:11 PM
Dav0s Dav0s is offline
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the guide king is back!
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Old 29-07-05, 02:34 PM
FarFarAway FarFarAway is offline
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That is what a guide is meant to be about/looks like!!

PV you really are da man!!!
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  #4  
Old 29-07-05, 09:04 PM
NickS NickS is offline
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Mod reps mate!!!!
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Old 29-07-05, 09:21 PM
JN JN is offline
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Holy crap PV, that guide was AWESOME

The guide king is in da house

You should also meantion that attatching LED's to high voltage can sometimes make the LED launch itself (minus feet) into the air
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Old 29-07-05, 09:34 PM
PV5150 PV5150 is offline
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Thanks a bunch guys. XMS, I'll put in your request.
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"Jonathan 'Fatal1ty' Wendel may be 12-time world gaming champ, but how does he cope inside a 50c hot box sucking on a heavy load?":rocker::rocker:
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Old 30-07-05, 11:41 AM
balilu balilu is offline
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wow great guide
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Old 30-07-05, 02:15 PM
bloodthirst bloodthirst is offline
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PV only cat 5 not cat 6 as well?
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Old 30-07-05, 03:44 PM
PV5150 PV5150 is offline
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Thanks again, are we able to use guides like this. Is it worth me doing some more, feedback please!!! hg007 I did say during the guide that both Cat 5 and Cat 6 cables were able to be tested with this, as they both have eight wires
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"Jonathan 'Fatal1ty' Wendel may be 12-time world gaming champ, but how does he cope inside a 50c hot box sucking on a heavy load?":rocker::rocker:
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  #10  
Old 30-07-05, 04:36 PM
NickS NickS is offline
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The only difference, HG, is the speed.

Theres Cat 5, Cat 5e, and Cat 6. (theres others but these are the msot common to the end user)

Use Cat5 & Cat 5e for 10/100 networks, while Cat 6 is better for 100/1000 networks.

Cat 6 is 500MHz, Cat 5e is 350MHz, and cat 5 is i think 300MHz but dont quote me onnthat

cat stands for category also.

hope i helped
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700GB of Storage :: ATi Xpess200 :: Sharp AQUOS 32" 720p





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