Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Noise filter ?

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

jpx(at)qenesis.com
Guest

Posted: Fri Jan 01, 2010 3:26 pm Post subject: Noise filter ?

On my Cessna 172, the strobe lights caused "tick" sounds.  It was  

eliminated by placing a diode and then a large capacitor on the supply  

line to the audio panel, which reduced the brief dips in power when  

the strobe packs charged.



In my Tundra, I effectively have the same setup.  I plan to put a  

large capacitor on the essential bus, which is connected with a bridge  

rectifier as in Z13/8.



However, my second radio is on my main bus.  Should I stick a diode  

and capacitor in its feed line after the fuse ?  Or should I plan  

instead to rectifiy any noise issues if I actually have them ?  My  

anti-collision lights will be LEDs, not strobes, but I tend to think  

clean power is good power.



Jeff Page

Dream Aircraft Tundra #10

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jan 02, 2010 9:43 am Post subject: Noise filter ?

 	  Quote: 	
		  However, my second radio is on my main bus.  Should I stick a diode

and capacitor in its feed line after the fuse ?  Or should I plan

instead to rectifiy any noise issues if I actually have them ?  My

anti-collision lights will be LEDs, not strobes, but I tend to think

clean power is good power.


	


   Jeff, I wouldn't strike out to solve a "noise" problem

   that has yet to manifest itself. Many moons ago a builder

   called me one night to describe how he had shielded the

   majority of his system's wiring, put off the shelf filters

   on all potential victims and antagonists and was calling

   to ask, "is there anything I've overlooked?"



   I had to ask, "Gee, how does your noise problem manifest

   itself?"



   "Oh," he replies, "I'm still building. The airplane hasn't

   flown yet."



   This is a tip-of-the-bell-curve example of how NOT

   to approach the design and fabrication of a new system

   in an airplane.



   Keep in mind that the majority of antagonist/victim

   accessories are DESIGNED with their target application

   in mind. We consider DO-160 EMC and MIL-STD-704 power

   studies that teach us how to LIVE with a certain amount

   of noise on the bus while LIMITING how much noise

   we allow to be generated on the bus.



   I've seen dozens of products offered like the ubiquitous

   "surge protection" devices for computers . . . except

   these are intended to ward off evil spirits and slay

   dragons that are reputed to live on your airplane's

   power system.



   I think I spoke about extra-ordinary prophylactic

   noise mitigation in the chapter on noise in the

   'Connection. Once you've shielded p-leads and

   crafted single point grounds, your probability

   of noise problems goes down to a tiny fraction of

   what's possible.



   The guy who called me about his noise mitigation

   program expended many hours, dollars and several

   pounds of empty weight on a useless activity.

   I can tell you that tens of thousands of strobe

   systems (and other potentially noisy appliances)

   have been successfully integrated into both TC

   and OBAM aircraft with no noise dragons to slay.



   Put the stuff all together first using ground

   rules established by decades of lessons-learned

   and let's tackle a noise problem later. It's

   likely that it won't show up.



   Bob . . .





        Bob . . .

                    ////

                   (o o)

    ===========o00o=(_)=o00o=========

    < Go ahead, make my day . . .   >

    < show me where I'm wrong.      >

    =================================

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum