Advertise on Bikeforums.net



User Tag List

Results 1 to 14 of 14
  1. #1
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Would this shield a cable?

    Am I correct that shielded cable is shielded because of the foil which wraps the cable (underneath the layer of insulation). Then the ground wire will be connected to something on either end to pass the "stray" charges.
    Now, I have an application which carries a +5vDC pulse through 22awg wire into a drive. The manual of he drive warns that this line is sensitive to external noise. Frequencies of 100khz will likely be seen by this line.

    So I am definitely routing the 16 wires which will be carrying 160vDC as far away as I can from those 5v lines. But, there's only so far I can separate them. At the closest point, they will be 2" apart from eachother. So I was wondering, if I carefully wrapped aluminum foil around the wire, would it shield it? The wire will not be moving, so I don't concern about breakage.
    C://dos
    C://dos.run
    run.dos.run

  2. #2
    The Site Administrator: Currently at home recovering from a couple of strokes,please contact my assistnt admins for forum issues Tom Stormcrowe's Avatar
    Join Date
    Mar 2006
    Location
    South Florida
    My Bikes
    Techna Wheelchair and a Sun EZ 3 Recumbent Trike
    Posts
    16,158
    Mentioned
    12 Post(s)
    Tagged
    4 Thread(s)
    Quote Originally Posted by phantomcow2
    Am I correct that shielded cable is shielded because of the foil which wraps the cable (underneath the layer of insulation). Then the ground wire will be connected to something on either end to pass the "stray" charges.
    Now, I have an application which carries a +5vDC pulse through 22awg wire into a drive. The manual of he drive warns that this line is sensitive to external noise. Frequencies of 100khz will likely be seen by this line.

    So I am definitely routing the 16 wires which will be carrying 160vDC as far away as I can from those 5v lines. But, there's only so far I can separate them. At the closest point, they will be 2" apart from eachother. So I was wondering, if I carefully wrapped aluminum foil around the wire, would it shield it? The wire will not be moving, so I don't concern about breakage.
    It should, as a result of the Faraday effect. I'm sure there are others here that can either confirm or deny, but that's my opinion...
    on light duty due to illness; please contact my assistants for forum issues. They are Siu Blue Wind, or CbadRider or the other 3 star folk. I am currently at home recovering from a couple of strokes. I am making good progress, happily.


    . “He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you.”- Fredrick Nietzsche

    "We can judge the heart of a man by his treatment of animals." - Immanuel Kant

  3. #3
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    So it IS the faraday effect. I mentioned that today during a presentation, and I could not tell what the look on my teachers face meant.
    C://dos
    C://dos.run
    run.dos.run

  4. #4
    Senior Member randya's Avatar
    Join Date
    Jul 2003
    Location
    in bed with your mom
    My Bikes
    who cares?
    Posts
    13,696
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Shielded cable is basically any kind of coaxial cable with the ground wire on the outside. Sometimes it's foil, sometimes it's braided wire, sometimes it's both. Usually it's to protect a weak or low-level audio or video signal from unwanted electronic 'noise'. Examples of shielded coaxial cables in everyday use include cable TV wire, audio cable used to connect audio components to a preamp or receiver, and electric guitar cords.

  5. #5
    Life is good RonH's Avatar
    Join Date
    Jan 2001
    Location
    Between Crystal River and Hernando, Florida, 6 miles west of the Withlacoochee Trail
    My Bikes
    I've had several since 1999 but have settled on my beloved 2001 Litespeed Tuscany and my latest, a 2015 Cannondale Supersix EVO
    Posts
    13,881
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    A braided shield usually works better. Can you replace the wire carring the 5V with a braid shielded cable? If you can, only ground one end of the shield.
    My bikes: 2001 Litespeed Tuscany---2015 Cannondale Supersix EVO carbon

    I thought of that while riding my bicycle -- Albert Einstein

  6. #6
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I've got 6 conductor shielded cable already, with foil and the brade. All is grounded already on both ends. That reminds me, the 160v carrying cables are already using that shielded cable. That should mean no electric field will leave the cable housing then.
    C://dos
    C://dos.run
    run.dos.run

  7. #7
    Life is good RonH's Avatar
    Join Date
    Jan 2001
    Location
    Between Crystal River and Hernando, Florida, 6 miles west of the Withlacoochee Trail
    My Bikes
    I've had several since 1999 but have settled on my beloved 2001 Litespeed Tuscany and my latest, a 2015 Cannondale Supersix EVO
    Posts
    13,881
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Just make sure you ground only one end. If you ground both ends you could have a ground loop carrying current that could make things much worse.
    My bikes: 2001 Litespeed Tuscany---2015 Cannondale Supersix EVO carbon

    I thought of that while riding my bicycle -- Albert Einstein

  8. #8
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I thought ground on both ends was acceptable practice. One end is connected to the terminal on the drive made for ground, and the other end to a ground terminal on my mill.
    C://dos
    C://dos.run
    run.dos.run

  9. #9
    riding once again jschen's Avatar
    Join Date
    Oct 2005
    Location
    San Diego, CA
    My Bikes
    '06 Cervelo R3, '05 Specialized Allez
    Posts
    7,360
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Not all shielding is of equal quality. While an idealized Faraday cage is perfectly shielding, reality and idealized models don't perfectly coincide. Also note that how two lines come near each other can matter. Two parallel lines can wreak far more havoc on each other than two lines that cross perpendicular to each other but then never meet again. How you set up the lines is very important if you want minimal cross talk.

    I saw this happen once back when I worked in a biotech. I was helping our IT guy set up a laptop for a presentation when he had trouble getting an Ethernet connection to be stable. I noticed his Ethernet line and power line parallel to each other and lying right next to each other. Sure enough, separating them by a few more inches (crossing only out of necessity near the laptop because of where the ports were) resolved the issue.
    If you notice this notice then you will notice that this notice is not worth noticing.

  10. #10
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Heh, I know a funny instance with my TV downstairs. THis is a cheapo Sony, 10 years old, probably 10 year old cable too. Anyways, I plug in my stepper motor drivers for configuration, as soon as current is applied to the motor, instant fuzz on TV screen. Those drives are choppers, so they are chopping the current at about 20khz. And the coaxial cable for the TV is a good foot away from the step motor wires. It does not have this issue with other drives. But, the max I've put in with other drives is 28v. This drive direct rectifies the AC, so 160v!

    Wonder if it will do that with my shielded cable, maybe I should go test. THen again, my 10+ year old coax might need to be replaced as well!
    C://dos
    C://dos.run
    run.dos.run

  11. #11
    The quieter you become... Falkon's Avatar
    Join Date
    Jan 2006
    Location
    Huntsville, AL
    My Bikes
    1973 Raleigh Superbe, 2006 Trek 4300 with no original parts, 1984 Ciocc, Custom Keith Anderson
    Posts
    1,283
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The cross talk issue is why ethernet cable is made up of twisted pairs. the fields cancel each other out.
    Quote Originally Posted by TechKnowGN
    San Jose has to be the most boring place I've ever been. And I live in Ohio.

  12. #12
    riding once again jschen's Avatar
    Join Date
    Oct 2005
    Location
    San Diego, CA
    My Bikes
    '06 Cervelo R3, '05 Specialized Allez
    Posts
    7,360
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by phantomcow2
    Wonder if it will do that with my shielded cable, maybe I should go test. THen again, my 10+ year old coax might need to be replaced as well!
    The understanding of how to shield a cable hasn't exactly changed in recent times. Nothing wrong with old cables.
    If you notice this notice then you will notice that this notice is not worth noticing.

  13. #13
    Senior Member randya's Avatar
    Join Date
    Jul 2003
    Location
    in bed with your mom
    My Bikes
    who cares?
    Posts
    13,696
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by phantomcow2
    I thought ground on both ends was acceptable practice. One end is connected to the terminal on the drive made for ground, and the other end to a ground terminal on my mill.
    If you ground both ends, there could still be an electrical potential, depending on the relative potential at each grounded end. So I agree, if possible/necessary, ground only one end. I also agree that perpendicular wire crossings are better than parallel runs if you want to avoid interference...

  14. #14
    Chairman of the Bored catatonic's Avatar
    Join Date
    May 2004
    Location
    St. Petersburg, FL
    My Bikes
    2004 Raleigh Talus, 2001 Motobecane Vent Noir (Custom build for heavy riders)
    Posts
    5,825
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    You need to anchor the foil to a ground. Single ended as mentioned.

    As a very small second job, I make quality audio cables, and I always anchor the ground on one end. That's also the REAL reason why you see directional arrows on some shielded audio cables....the shield is anchored on a single end, and the anchored end should be the source end, so that noise doesn't travel to the next component. The arrows should always be pointing towards the non-anchored end....it's easier for an untrained person to figure out "the sound comes FROM the CD player TO the amp...the the arrows should point TO the amp", than to have it the other way.
    -------- __@
    ----- _`\<,_
    ---- (*)/ (*)
    ~~~~~~~~~~~~~~~~
    Ring Ring, Ring Ring, the bell went Ring Ring Ring.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •