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geekhack Community => Keyboards => Topic started by: sethstorm on Sun, 03 January 2010, 16:28:49

Title: On using RJ-45 connectors in place of SDL.
Post by: sethstorm on Sun, 03 January 2010, 16:28:49: (http://geekhack.org/attachment.php?attachmentid=6965&stc=1&d=1262551310)

Since there was no SDL connector (but possibly some space to put one in), I decided to make one of these for another terminal keyboard.

My question for this, what kind of issues would I run into regarding the use of regular twisted pair (cat5e/cat6) cable(as opposed to shielded)?

If there's no major issue, one could just wire up 2 of these, one of these jacks going to a suitable keyboard connector. Connect a straight-through cable to the two jacks, and you would be done.

Pinout:
Code: [Select]
BERG* RJ45 Pin 1 -> Pin 1 Pin 2 -> Pin 2 Pin 3 -> Pin 3 Pin 4 -> Pin 4 Pin 5 -> Pin 5Notes:
6-8 are unused, unless you want to wire up a speaker there too.

* Pinout based on Kishy's terminal keyboard post. Adjust as necessary for your keyboard.
Title: On using RJ-45 connectors in place of SDL.
Post by: InSanCen on Sun, 03 January 2010, 18:32:09: I can't see a problem with it, as long as it's pinned accordingly. I have used 5M of CAT5 LSZH Purple (http://www.maplin.co.uk/module.aspx?moduleno=19868) cable when I got sick of the tabs on SDL's breaking, and modded my '89 to a 9 Pin D-Sub instead.
Title: On using RJ-45 connectors in place of SDL.
Post by: sethstorm on Sun, 03 January 2010, 18:46:32: My concerns are more of crosstalk/esd/grounding given the lack of a proper shield for the length of the cable, thus my question regarding the use of unshielded twisted pair.
Title: On using RJ-45 connectors in place of SDL.
Post by: InSanCen on Sun, 03 January 2010, 18:51:53: Quote from: sethstorm;147657
My concerns are more of crosstalk/esd/grounding given the lack of a proper shield for the length of the cable, thus my question regarding the use of unshielded twisted pair.

As I said, I used unshielded CAT5e, and didn't have a problem using 5M of it. I subsequently cut it shorter, as I overestimated the length I would need, but it functioned just as it would on it's original SDL cable, without any worries about breaking tabs etc. If you are unsure, just pop for a couple of metres of FTP CAT5. Shouldn't cost more than a couple of $/£/Euro's.
Title: On using RJ-45 connectors in place of SDL.
Post by: microsoft windows on Sun, 03 January 2010, 19:31:24: Quote from: ripster;147659
Well, I think that's what InSancen is saying - no shielding is OK in this application.

Now you CAN do this trick if you are worried and if nothing else it'll make the cable a lot cleaner.
Show Image
(http://geekhack.org/attachment.php?attachmentid=6979&stc=1&d=1262566095)

For PC fan cables I would braid the cables to make it neater inside the PC. I learned this trick from building guitar tube amps.

I call it the Little Jacob Rasta FanBoy Mod. Irie, Mon!

I don't have to worry about that as it is since Pentium III's only generate so much heat... No need for any fancy fan systems at all.
Title: On using RJ-45 connectors in place of SDL.
Post by: microsoft windows on Mon, 04 January 2010, 06:38:33: Whenever I need a new computer I always check the garbage at work for them. They're getting rid of a whole fleet of Dells that I could use for parts.
Title: On using RJ-45 connectors in place of SDL.
Post by: ch_123 on Mon, 04 January 2010, 09:11:09: Have fun finding something in a skip that can play GTA4.
Title: On using RJ-45 connectors in place of SDL.
Post by: ch_123 on Mon, 04 January 2010, 11:29:43: I had a Athlon 3800+ and a 6800GT, and even on the lowest settings it absolutely killed it.

On the other hand, I was able to upgrade to a dual core Athlon and a 9600GT for pretty cheap, and that was more than sufficient to run it.
Title: On using RJ-45 connectors in place of SDL.
Post by: sethstorm on Mon, 04 January 2010, 12:18:08: Quote from: microsoft windows;147734
Whenever I need a new computer I always check the garbage at work for them. They're getting rid of a whole fleet of Dells that I could use for parts.

I've done that, but only for routing/switching equipment and larger, more powerful computers.

Quote from: ch_123;147763
Have fun finding something in a skip that can play GTA4.

Don't need to. By the time things recover well enough for permanent work, this config is what you might find in a skip. Make your own conclusions.

Q6600, 8800GTX, Intel D975XBX2 w/ 4GB of DDR2-800.

As for the cable, looks like there shouldn't be much issue with it.
Title: On using RJ-45 connectors in place of SDL.
Post by: ch_123 on Mon, 04 January 2010, 12:45:29: I call it 'Skip hunting'
Title: On using RJ-45 connectors in place of SDL.
Post by: InSanCen on Mon, 04 January 2010, 17:43:40: Skip Scavenging.

I have scored a rather nice Dualie this way. Xeon 700's (Yup, 700Mhz) when a 1.2 was King IIRC. Turns out it was bulging caps (what turns them on so much?) on the board. 15 Minutes later with iron still cooling, et voila, it boots.

Now, if some kind soul would see fit to dispose of Quad socket G34's with, ohhh... 64GB of RAM, just before I take a peek in the skip, I'd be rather happy.