REFLECTOR: Intercom question

[Laurence Coen]

Clayton,

Having a ground at two physically different locations allows the connecting wire to act as an antenna.  Electromagnetic interference will cause a current to flow in the shield which in turn transfers that noise to the circuit it's supposed to shield.  Try Googleing "electronic ground loop".

Larry Coen
N136LC


From: Clayton Chase 
Sent: Monday, February 18, 2013 3:05 PM
To: Velocity Aircraft Owners and Builders list 
Subject: Re: REFLECTOR: Intercom question


How bad is it to have a loop in the ground circuit?    I wouldn't think it's a big problem as long as all ground paths are solid and can handle the current.


JOKE ->  I tried looking up 'ground loop aviation' on google but got a whole bunch of stuff unrelated to electrical systems.




On Mon, Feb 18, 2013 at 12:53 PM, Laurence Coen <lwcoen at hotmail.com> wrote:

  There is no mention of what kind of airplane your friend has.  The way to wire the audio is different for a metal plane than a glass plane.  In a metal plane, mounting the jack will ground it to the airframe and if you connect the shield at that point there will be two ground paths (ground loop).  With a glass plane the ground return can be via the shield since the jack is not grounded to the airframe. See the attached.

  Larry Coen
  N136LC


  From: Matt Bucko 
  Sent: Sunday, February 17, 2013 10:53 PM
  To: Velocity Aircraft Owners and Builders list 
  Subject: Re: REFLECTOR: Intercom question


  Thank you.
  Bucko

  On 2/17/2013 9:05 PM, Glenn Falkenberg wrote:

    To float the shield means to not terminate it at the component or a ground.  Usually the shield is trimmed back a couple of inches and shrink sleeved or a solder sleeved. 

    On Feb 17, 2013 6:37 PM, "Matt Bucko" <mbuc310 at cox.net> wrote:

      Would you please describe "float the shield at the jack".

      Bucko

      On 2/17/2013 7:04 PM, Scott Derrick wrote:

        agreed 

        Glenn Falkenberg <airmech2 at gmail.com> wrote:


        I think the best way would be use a shielded twisted pair.  Float the shield at the Jack and take shield to ground at intercom panel.

        On Feb 17, 2013 4:25 PM, "Dan Schindler" <danpilot91 at gmail.com> wrote:

          My friends airplane intercom is wired in such a way that each jack only has 1 wire running to it. Utilizing the shielded portion of the wire as the common ground. Is this an acceptable way to do this. He is getting feedback in his headset when he pushes the PTT.

          Thank you,

          Dan Schindler
          _______________________________________________
          To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector

          Visit the gallery!  www.tvbf.org/gallery
          user:pw = tvbf:jamaicangoose
          Check new archives: www.tvbf.org/pipermail
          Check old archives: http://www.tvbf.org/archives/velocity/maillist.html


         

_______________________________________________
To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector

Visit the gallery!  www.tvbf.org/gallery
user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail
Check old archives: http://www.tvbf.org/archives/velocity/maillist.html

      -- 


      _______________________________________________
      To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector

      Visit the gallery!  www.tvbf.org/gallery
      user:pw = tvbf:jamaicangoose
      Check new archives: www.tvbf.org/pipermail
      Check old archives: http://www.tvbf.org/archives/velocity/maillist.html


     

_______________________________________________
To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector

Visit the gallery!  www.tvbf.org/gallery
user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail
Check old archives: http://www.tvbf.org/archives/velocity/maillist.html

  -- 



------------------------------------------------------------------------------


  _______________________________________________
  To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector

  Visit the gallery!  www.tvbf.org/gallery
  user:pw = tvbf:jamaicangoose
  Check new archives: www.tvbf.org/pipermail
  Check old archives: http://www.tvbf.org/archives/velocity/maillist.html


  _______________________________________________
  To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector

  Visit the gallery!  www.tvbf.org/gallery
  user:pw = tvbf:jamaicangoose
  Check new archives: www.tvbf.org/pipermail
  Check old archives: http://www.tvbf.org/archives/velocity/maillist.html





--------------------------------------------------------------------------------


_______________________________________________
To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector

Visit the gallery!  www.tvbf.org/gallery
user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail
Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20130218/5e56c374/attachment-0001.html>