Fun challenge: cat-5 cable tester

[krw]

Sort of semi-OT:

I have a misty distant memeory that the CAT-5 designation actually
referred to plenum wiring flame-proof and smoke-proof qualities, and
had nothing to do with the number of conductors, their twistedness, or
the type of connectors. Am I thinking of something else?

Cat-5 is four twisted pair, as used in 100base-T. Not all cat-5
(or cat-anything) is plenum rated. To be run in a plenum it has to
be rated, um, "plenum". ;-) Plenum rated cat-5 cable is 2-5x the
price of non-plenum rated cable.

 

[Spehro Pefhany]

Sort of semi-OT:

I have a misty distant memeory that the CAT-5 designation actually
referred to plenum wiring flame-proof and smoke-proof qualities, and
had nothing to do with the number of conductors, their twistedness, or
the type of connectors. Am I thinking of something else?

http://en.wikipedia.org/wiki/Category_5_cable


Best regards,
Spehro Pefhany

 

[JeffM]

Sort of semi-OT:
I have a misty distant memeory that the CAT-5 designation actually
referred to plenum wiring flame-proof and smoke-proof qualities, and
had nothing to do with the number of conductors, their twistedness, or
the type of connectors. Am I thinking of something else?

NEMA ratings?

 

[krw]

http://en.wikipedia.org/wiki/Category_5_cable

Speff, is your clock stuck?

 

[Marco Licetti]

means five cats 9dog not included)

 

[Spehro Pefhany]

Speff, is your clock stuck?

Ah, I keep it running about 10-15 minutes fast, just because.


Best regards,
Spehro Pefhany

 

[Rich Grise]

I had this idea, and toyed with it a while (including some computer
simulations), but didn't go very far with it. I thought I'd post it
here in case anyone wants a brain teaser for the weekend.

Consider this tool: a cat-5 cable tester.

Goal: To make a tester that works entirely from the user's side,
without needing batteries at the far end.

Circuit:

+-----+
| | P0/AD0 R1 R11
| |----------\/\/\--< <--------> >----\/\/\ ---+
| | P1/AD0 R2 R12 |
| |----------\/\/\--< <--------> >----\/\/\ ---+
| | P2/AD2 R3 R13 |

But, does the tech have to go to the other end to install the resistor
network?

If he can go there twice in one run, then you won't need any resistors
or diodes or anything. Make two shorting jacks:

1 o-------+
|
2 o-------+

3 o-------+
|
4 o-------+

5 o-------+
|
6 o-------+

7 o-------+
|
8 o-------+

and

1 o----------------+
|
2 o-------+ |
| |
3 o-------+ |
|
4 o-------+ |
| |
5 o-------+ |
|
6 o-------+ |
| |
7 o-------+ |
|
8 o----------------+

And just check each pair in turn for continuity and shorts to other
pairs.

Or, like Michael A said, use a TDR.

Good Luck!
Rich

 

[Rich Grise]

No, I'm pretty sure I said resistor network.

I'm rather disappointed in the response I've gotten from this. I've
seen a lot of people tell my why it's a bad design, or all the things
it can't do, or alternate ways to build cable testers, and yet NOBODY
has addressed the original challenge.

That's because they all know better. The original design is just plain
silly. It'd be a nightmare to try to get it to do what you seem to want
to do. If what you want to do is test cables, then use my two shorting
jacks, otherwise, just get a handful of resistors, put a stack in a
1-2-4-8-16-... sequence, and start playing with the damn thing!

Good Luck!
Rich

 

[DJ Delorie]

If he can go there twice in one run,

That would make his job twice as hard, wouldn't it?

Make two shorting jacks:

Your plan won't detect swapping the 1-2 pair with the 3-4 pair, for
example.

 

[DJ Delorie]

That's because they all know better.

That wasn't my point. OF COURSE THERE ARE BETTER CABLE TESTERS.

It'd be a nightmare to try to get it to do what you seem to want to
do.

That's what makes it an interesting challenge!

 

[The Real Andy]

No, I'm pretty sure I said resistor network.

Well thats fucken fantastic. If you know what you want to do then why
are you here asking stupid questions about irrelavent drivel?

I'm rather disappointed in the response I've gotten from this. I've
seen a lot of people tell my why it's a bad design, or all the things
it can't do, or alternate ways to build cable testers, and yet NOBODY
has addressed the original challenge.

Its because no one really gives a ****, and most people here would
take the simple solution.

GIVEN THE SCHEMATIC I POSTED, what resistor values let you detect bad
cables (as far as the design allows) with the least ADC bits?

Do your own homework.

 

[DJ Delorie]

Well thats fucken fantastic. If you know what you want to do then
why are you here asking stupid questions about irrelavent drivel?

Obviously, people like you just aren't interested in mental
challenges.

And obviously you can't read, because the subject clearly states "fun
challenge". You probably don't do the crossword puzzle either,
because the editor should have found the answers himself.

Do your own homework.

Sorry, I've been out of school for two decades now.
http://www.delorie.com/users/dj/resume/

 

[The Real Andy]

Obviously, people like you just aren't interested in mental
challenges.

Define a 'Mental Challenge'. Working with the business is mentally
challenging.

And obviously you can't read, because the subject clearly states "fun
challenge". You probably don't do the crossword puzzle either,
because the editor should have found the answers himself.

I have a life, thats the difference.

Sorry, I've been out of school for two decades now.
http://www.delorie.com/users/dj/resume/

Thats the kind of resume I dump straight into the bin. Esentially nil
commercial experience, and the rest spent re-inventing the wheel.