X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from inca.al.noaa.gov ([140.172.240.8] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTPS id 987673 for flyrotary@lancaironline.net; Thu, 16 Feb 2006 14:10:57 -0500 Received-SPF: none receiver=logan.com; client-ip=140.172.240.8; envelope-from=william.p.dube@noaa.gov Received: from [140.172.241.126] (mungo.al.noaa.gov [140.172.241.126]) by inca.al.noaa.gov (8.13.5/8.13.5) with ESMTP id k1GJACC5026985 for ; Thu, 16 Feb 2006 12:10:13 -0700 (MST) Message-ID: <43F4CD26.6060901@noaa.gov> Date: Thu, 16 Feb 2006 12:06:14 -0700 From: Bill Dube Reply-To: william.p.dube@noaa.gov Organization: NOAA Aeronomy Lab User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Radio noise saga References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit No need for braid. Just keep the cables next to each other. If you want to get fancy, you could gently twist the cables. Barry Gardner wrote: > Bill and other knowledgable folks, > > Is there any value in running a braided shielding inside the conduit > that will carry the power leads? I'm building a plane like Buly's and > want to know if that's something I should just build into my > electrical raceway. Thanks. > > Barry Gardner > Wheaton, IL > > Bill Dube wrote: > >> The separated power leads radiate noise quite well. They are a giant >> loop antenna that is transmitting any ripple on the current to the >> battery. Alternator whine, motor whine, ingnition system input ripple >> all will radiate from such a loop. >> >> This is a very common problem on homebuilt electric vehciles. With >> the large battery pack, folks often fine it convienient to run the >> power leads up one side of the car and back on the other. The hash >> from the motor controller and/or the charger make it impossible to >> use anything electronic inside the car if you wire it that way. >> Sometimes, the motor controller throttle input will pick up the >> output hash from such a loop and make the car undrivable. >> >> Always run power leads as a pair. Keep the "presented area" low to >> reduce the transmitted noise. >> >> You have found the problem. >> >> >>> >>> Twisted pair only reduces noise in signals transmitted THROUGH the >>> wire, and it only works if the receiver uses a differential signal. >>> It doesn't help with power wires. The curious can drop by: >>> >>> http://www.duxcw.com/digest/Howto/network/cable/cable4.htm >>> >>> It's a fairly good, brief description of what goes on. You'll >>> usually only find twisted pair in LAN cabling. >>> >>> Regards, >>> Chad >>> >>> -- >>> Homepage: http://www.flyrotary.com/ >>> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >>> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >> > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >