Introduction: How to Make Ethernet Cable Checker

Picture of How to Make Ethernet Cable Checker

My ADSL Modem is far away from my home so I use Ethernet cable to bring internet to my home...But sometimes internet is disconnected. I noticed that is is the fault of cable. So I made this small but very helpful gadget...Concept behind the project is very simple.... In Ethernet, connection is established through only 4 wires out of 8. (I will discuss Ethernet cable jack pinout in next steps)...So I checked only 4 wires...If these are OK cable is suitable for Broadband Internet. But If some LEDs are not ON or all of them are OFF then Cable is cracked/broken...

Step 1: Part List

Picture of Part List

1). RJ-45 Socket x2

2). 1.5 Volt AA Battery x2

3). AA Battery Holder x1

4). Matrix Board x1

5). 3 volt LED x3

6). 3 volt small LED for Power Indication x1

You should also have wires and soldering experience and proper soldering tools (Soldering Wire, soldering iron, soldering rosin, etc.).

Step 2: The Power Unit - One End

Picture of The Power Unit - One End

This is the power source for LEDs. I used RJ-45 Socket. And I used 2 AA batteries (1.5v*2 = 3 volts) to power 3 LEDs on the Second End on other side of wire.

Step 3: LED Indicator Unit - Other End

Picture of LED Indicator Unit - Other End

On the other side of wire I made a small unit containing 3 LEDs to check the 4 wires of Ethernet cable. 3 LEDs are for 4 pins (3 pins are +ive, one for each LED While 1 pin in for -ive/ground, common for each LED).

Solder the 1,2,3 and 6 number pins of RJ-45 Socket to +ive and -ive terminals of LEDs respectively. That's All...

Step 4: Ethernet Cable Pinout

Picture of Ethernet Cable Pinout

Step 5: Circuit Diagram

Picture of Circuit Diagram

Step 6: Checking the Cable

Picture of Checking the Cable

I have checked my 200 feet cable with my cable checker....

To check the long distance cable you have to do only a small effort, plug one end of cable on Power Unit and other end of cable on LED Indicating Unit.
If all 3 LEDs are ON, Your cable is Okay.

If any of these LED is OFF, Cable is broken or Connectors on the ends of cable are not connected to cables properly.

Hence you can diagnose any Ethernet cable on your own with the help of this small but very useful tool...

Please vote for this...Thanks..!!!


Zaeem Khan (author)2015-10-24

very well... (y) Its might me helpful. I am also a student of Computer Science. I will make and test this one and I thought it will work as you described.

Sunny Yoshima Taru (author)2015-10-24

Tahuna wa'ora ze nuf.

MujtabaAlAhmad (author)2015-10-24

Thats Perfect small but very useful tool.

Babr Rohinz (author)2015-10-24

Nice project....Do you tested this properly for Ethernet connection of every type connection ?

It test it in my connection as I described above in description. And I sure this will work perfect for small scale connection network. work it can't be used in the connection having POV (Power Over Ethernet) so Do'nt use it there.

Ahsan Babu (author)2015-10-24

Bohat aala jnaab.... Great Idea... (y) :-D

Syed Umair Shah (author)2015-10-24

bohat acha ha yr...kesay bnaya.

Khan Baba (author)2015-10-24

perfect work (y)

Shah AlHasan (author)2015-10-24

هو أداة جيدة للغاية. أنا أحب ذلك لجعل. عمل جميل وإخوانه

شكرا سيدي

Robret Sohal (author)2015-10-24

Nice job Tehseen. I will use this to check the connections in my Ethernet networking while making Films.

Urooj Rani (author)2015-10-23

small but useful (y) ....Yeah nice thing

Zubair Ali Khan (author)2015-10-23

Thats grate (y)

Anas Rehmani (author)2015-10-23

Okay its funtastic small but useful tool. But can it be used for gegabite connection, etc. ?

Thanks. No It is only for megabites connection. because it uses only 4 wires out of 8.... But you can also make 8 wire checker similarly.

Rana Qamar (author)2015-10-23

That's perfect Tehseen. I will sure make this. because I often need this type of gadgets. (y)

SpankyO (author)2015-08-25

Nice work :) and Yes a Box would be great, and i was thinking.. even something as simple as a push button switch or toggle switch. between the power and the first for each line and you'll break the circuit so you can see if a wire is crossed ..?

TehseenHasan56 (author)SpankyO2015-08-26

Yeah its also a good point...Thanks!

helllordkb (author)2015-08-14

Great instructable. but 1 WORD OF WARNING. this will only give you verification of continuity on all wires. It won't verify you have each RJ45 connector pin to the right color wire on each end. You still need to make sure you have all the right colors connected to the same pins on the RJ45 connector at both ends.

if some of your wires were connected too different pins on the RJ45 connector at one end vs the other, you'd still get a solid light.

It will work OK If we connect connector according to IEEE rules about RJ45 connector for Ethernet....

true, just saying this won't give you indication if you've messed that up... and i've seen it get messed up and people having to cut and terminate again.

If you wanted to get fancy you could use different color leds for the different wire colors.

You could get even more fancy using PWM and control the color on the led to match the color of the wire. For the striped wires you could make them blnk and the solid wires you could make them always lit and not blink

magkopian (author)helllordkb2015-08-22

Even if you use different color LEDs it won't make a difference because even if the order of the wires is not right the LEDs will still turn on if there is continuity. To check the order you need a circuit that will turn on all LEDs one at a time and watch the order that the LEDs turn on. If all the LEDs turn on and at the right order that means the cable is fine.

yes you are right...

mleeee (author)2015-08-18

Does not check pairs are correct, just checks continuity.

It's important a wire is twisted with its correct pair, as shown in the 568B picture.

You could swap individual wires around in the plugs on each end, and as long as a wire was connected to the same pin at each end, this circuit will show all greens.

So, good shot, but not good enough for a correct ethernet pairing check, and using this checker, plus some mis-pairing, your ethernet may not run. Careful.

Oh dear ... Just read the chap below - who makes the same point!


FaisalJ2 (author)2015-08-12

Best project very nice

TehseenHasan56 (author)FaisalJ22015-08-14

Thanks !

Clapoti (author)2015-08-13

Very nice project :)
I might adapt this to my situation where I have gigabit ethernet :)

TehseenHasan56 (author)Clapoti2015-08-14

Thanks....For gigabit data connection you will attach 7 LEDs on each pin....and one -ive/earth pin....

czarnian (author)2015-08-13

For gigabit ethernet, just add one LED for each cable. basicly what you are doing is making a loop circuit qith a LED indicating a closed loop. The basic of the idea is there, just keep adding positive leads on the batt side and LEDS on the test side.

TehseenHasan56 (author)czarnian2015-08-14

Yes if some one wants to check GBps of data....principle is same...use all wires and attach 7 LEDs of each wire and 1 -ive wire....

MichaelS99 (author)2015-08-13

FYI Gigabit Ethernet requires all 8 wires, not just 4.

Thanks all of you guys.... Yes this cable tester is for maximum 150 MBps data connection... if some one wants to check GBps of data....principle is same...use all wires and attach 7 LEDs of each wire and 1 -ive wire....

dragonem (author)MichaelS992015-08-13

Also need to have the extra pairs if run for a multi-line phone or run PPoe/PoE

magkopian (author)dragonem2015-08-13

Furthermore, this will only tell you if there is a good connection
on all 4 wires from one end of the cable to the other, it won't tell you
if you accidentally put the wires in incorrect order before crimping
the cable. But you can achieve that by using a simple 555 timer together
with 4017 like this

mattcintosh (author)2015-08-13

I actually encountered a gamer motherboard that would check cables in BIOS. It even had a feature that would determine the *length* of the cable. On a 25ft cable, it was only off by a foot or two.

I have 260ft cable....And I chacked that cable using this....And it worked very well...

peyge (author)2015-08-13

Having the 3 LEDs on doesn't mean your cable is OK. You could have a short circuit between 2 wires and not know using this tester.

TehseenHasan56 (author)peyge2015-08-14

If there is short circuit...cable is there is problem and we will fine it....So we found that error with this tool....

Tamsuolis (author)2015-08-13

Has anybody know why is that wires 1 and 2 is a pair, 7 and 8 is a pair, but 3 and 4 could not be, it have to be 3 and 6, why those wires are separeted?

TehseenHasan56 (author)Tamsuolis2015-08-14

I think it is IEEE rule...Maybe it is due to Hardware devices....

martinhui (author)2015-08-11

Alternately use a ohm meter to check all the pairs, cable pairs are serial by diodes, you can identify broken pairs, wrong pairs or crossed pairs, I using these.

martinhui (author)2015-08-11

I have a slightly suggestion, as the cable is long your led will properly not lit, you can light up only one led via a npn transistor biased by the diode serial pair of cable.

rafununu (author)2015-08-11

You can have a broken wire and a short circuit involving the same wire and all your leds will be on ! Don't smile, I've already got that.

A "smart" tester costs 5 €, let's say 7$.

wazalac18 (author)2015-08-11

nice ible...

i think this would be a good inclosure for your project,

it can accommodate all those parts ;
you can build LED panel/indicators on the face plate as well...

avinashk (author)2015-08-10

dear tehseen thanks for the simple
solutionfor big problem.since i too have same situation and looking for solution.becouse even iut of 3 pair of wires 1 is broken the internet wont work n you need to replace whole cable which is big job itself apart from money.with your gadget 1 can check wire conectivity and simply switch to good wire out of 6 wires .the 6 or 8 wires are only used for data transfer in lan network.hence if 1 is using only internet he can always have atleast 2 wires in spare in his cable
my 100 % ?marks to you,,,,,,,

DIY Hacks and How Tos (author)2015-08-09

Nice DIY cable checker.

About This Instructable




Bio: I'm student of Software Engineering.
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