AeroElectric-List Digest Archive

Fri 10/26/12


Total Messages Posted: 3



Today's Message Index:
----------------------
 
     1. 07:43 AM - Re: turn coordinator causing noice in headset (jerrytex)
     2. 08:09 AM - Re: Re: turn coordinator causing noise in headset (Roberto Waltman)
     3. 09:00 AM - Re: Re: turn coordinator causing noise in headset (Robert L. Nuckolls, III)
 
 
 


Message 1


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    Time: 07:43:15 AM PST US
    Subject: Re: turn coordinator causing noice in headset
    From: "jerrytex" <jery230@tconline.net>
    No I have not hooked up the T/C to a seperate power supply. I'll try that as soon as I can and report back. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=386038#386038


    Message 2


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    Time: 08:09:59 AM PST US
    From: Roberto Waltman <aero@rwaltman.com>
    Subject: Re: turn coordinator causing noise in headset
    jerrytex wrote: > The noise is there always, regardless of transmitting or receiving. I can put my headset on, turn on the master, listen to the gyro spin up in the headset, then turn on the landing the light, and the noise goes away. An uneducated guess: The noise is introduced via the supply bus, and turning the light on somehow provides a lower impedance path to ground that attenuates it. The suggestion to add capacitors sounds good, how many and where, that's a different story.


    Message 3


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    Time: 09:00:01 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: turn coordinator causing noise in headset
    At 10:07 AM 10/26/2012, you wrote: > >jerrytex wrote: >>The noise is there always, regardless of transmitting or receiving. >>I can put my headset on, turn on the master, listen to the gyro >>spin up in the headset, then turn on the landing the light, and the >>noise goes away. > >An uneducated guess: The noise is introduced via the supply bus, and >turning the light on somehow provides a lower impedance path to >ground that attenuates it. The suggestion to add capacitors sounds >good, how many and where, that's a different story. It's an intriguing symptom. The hypothesis has some weight. Waaayyyy back when, we believed that a battery offered an effective electromotive mass across the bus. That bubble burst when I was fine tuning the feedback loops on the B&C linear regulators. With a bus voltage above battery-delivery potential; greater than 12.5 volts and less than battery-charging potential; less than 14.0 volts, the battery is essentially 'open circuit'. The most challenging condition for bench marking regulator performance was with a fully charged battery and relatively light loads. Turning a even a 55w landing light on would appear as a parallel impedance on the order of 3 ohms . . . perhaps significant in comparison with the sum of impedances in this system. It would be interesting to probe the system with some test equipment . . . If this antagonist is propagating through the power leads, then an L/C filter having inductance facing the T/C is called for. The interesting detail is a notion that the noise spectrum covers VHF frequencies and gets into the victim via the antenna. This suggests that relatively small values of L/C would be effective. Bob . . .




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