[LAD] [semi-OT] midi snakes using CAT5?

Gene Heskett gene.heskett at verizon.net
Mon Nov 2 12:52:10 UTC 2009

On Monday 02 November 2009, Arnold Krille wrote:
>On Monday 02 November 2009 00:56:15 Gene Heskett wrote:
>> On Sunday 01 November 2009, Arnold Krille wrote:
>> >If you want to make use of the drilling of the pins in cat5, it should
>> > be 1+2 Midi 1
>> >3+6 Midi 2
>> >4+5 Midi 3
>> >7+8 Midi 4
>> >Why do you want to carry 5V? According to my docs, Midi is just Signal+
>> > and Signal- and shield. Which, when carried over Cat5, should be all on
>> > the shield.
>> Except that I have yet to see a piece of cat5 with shielding.
>Look for that STP or S/UTP or FTP cables :-)
>Honestly all the cables I make myself are from (single-)shielded twisted
> pair. And except for the cheap cables that come with some devices, all the
> cables I buy are shielded too (with no extra costs).
>Unshielded is usable to connect that slow wlan-repeater that can't really
> go more then 10MBits but for anything else in networking you should used
> shielded cable.
>And as Jörn is asking about using it in professional surroundings, it will
>most definitely be the shielded cable he is using...
>Have fun,
FWIW, I have around 120 feet of unshielded cat5 stretched around my property, 
with 100mbit cards at all points, from a switch I can see here in my den, 
down into the basement and out through the same hole the telco cable comes 
in, under the back porch floor, and up the house wall to an anchor point on 
the porch roof, thence to an anchor point at the peak of a workshop shed I 
built 10 years ago, down to a 4 port switch in there, then from that another 
cable is currently running out the shop door and about 35 feet across the 
back yard to a window in the garage, and 20 some feet to a test machine.  I 
can move something from here to that last machine at 10megabytes/second.  
Std, unshielded cat5.    The piece from the house to the shed has been 
swinging in the wind for about 6 years now, a never ending source of 
amazement to me that it hasn't failed.

My point is that the opto-isolation isn't required for ethernet since it is a 
transformer coupled differential circuit, therefore quite immune to 
longitudinal voltages caused by poor wiring practices, local high powered AM 
broadcasting signals etc.

Cheers, Gene
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