Shielding cables

Posted by Tono on April 25, 2013 at 8:04pm

Hi,

I was reading the arducopter manual information about the sonar and I saw this:

"You are also advised to use shielded cable with the shield grounded at the APM side."

http://code.google.com/p/arducopter/wiki/AC2_Sonar

I am using the Maxbotix LV-EZ0 and I removed it since it's not working fine, the quad starts bouncing like crazy and this is because I haven't added the 100uf cap or the 10 ohm resistor as explained in the manual, so tomorrow I will buy these parts.

Could you please advise what is the best way to shield a cable?

I would like to apply this same shield to the FPV cables.

I found an old usb cable and it seems to be shielded but it's impossible to solder, it won't stick no matter what I do to clean the wires, so I would like to use the silicon cables that I have but I want like to shield them.

Thank you.

Tono

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Replies

  • MR60
    Hugues April 25, 2013 at 11:45pm

    Hi Tono,

    I share here my experience. I have used special EMI thermo shrink to extract from them the inside metallic shield. It is like fabric that I wrapped around the cables as shown hereunder. I purchased this at www.sertim.com (they do not have an online shop but if you send an email with your request you can order and they ship).

    3692646251?profile=original

    (ignore the yellow comments on the picture, this was use for another topic; Just look at the grey fabric wrapped around cables). Another thing : you must solder this mettalic fabric on the ground only on one end. and VERY CAREFUL : this is conductive thus beware of shorts!!

    Concerning the sonar making your quad jumpy. I had the exact same behaviour although I followed all of the recommendations. My finding is that the erratic sonar (making the quad bouncy as you say) was due to a very sensitive electrical contact to the A0 connector. By keeping pressure on the connector, to force a good contact, I have no more jumpy readings. I still did not solve this one (I guess a definitive solution would be to solder the sonar wire on A0 but I do not want to do that)

     

     

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  • Craig Burden April 25, 2013 at 11:01pm
    If you can't find shielded cable, you can also plait your cables. It works very well and means you don't need to buy anything new
  • Julian Daly April 25, 2013 at 10:05pm

    Hi Tono

    I've just installed the sonar unit to my quad using the 10 ohm resistor and electrolytic capacitor.  I went out for it's first fly yesterday.  The only time I got any bounce was when a gust came through and the quad 'over-reacted'. But, it settled down after two bounces.  Quite 'dynamic' though!

    I tried putting my hand underneath to 'see what happened' and it shot up in the air as it should.

    I also was trying out the loiter mode, which seemed to work well.  I was even confident enough to push it around a bit.  That was until I put my hand into the prop!  

    Ouch!  It bit me!

    Lost some red fluid from the back of my fingers but the quad behaved itself!

    Have fun :)

    Julian

  • Euan Ramsay April 25, 2013 at 9:51pm
    I used the shielded cable from maxbotix and still get "the sonar bounce". I'll be interested to see pictures of the resistor package installed and how it improves things.
  • Mike R. April 25, 2013 at 8:24pm

    Another item - if you can get some solder flux (anywhere that sells solder) dip the tiny usb wires in it, then heat them up with the soldering iron until the flux sizzles - then add solder - that may help solve your issue with soldering the tiny wires.. The flux will eat at the wire a bit and allow the solder to stick better..

  • Mike R. April 25, 2013 at 8:21pm

    While I've used usb cables run between my sonar and apm on my two hexa's, if you can't solder the wires, look online for a small quantity of shielded balanced microphone wire - it's good stuff as well for this purpose..

    You may even want to check at your local music instrument store to see if they might have it by the foot..

    While I'm running the hexa's with major amps on full climb, I've never had an issue using standard servo wire sized cables to run my fpv with, with no foil, etc shielding - never a hint of interference..

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