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trigo(at)mail.telepac.pt
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 Posted: Wed Dec 31, 2008 7:05 am Post subject: Audio noise revisited |
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To noise specialists
I just concluded the installation of my Intercom, and although I took all the recommended measures to avoid ground loops and noise in general, I'm still hearing 2 whines, which after some time (many hours … J) of investigation, I think I identified the causes.
One is the Air/Fuel Ratio Monitor, because when I disconnect its ground wire, the most high-frequency whine disappears.
Which kind of filter (resistor, capacitor, diode, any other) can I install to eliminate this noise?
And should I put it in the power(+) red wire or the ground(-) black wire, or is it indifferent?
The other whine is from the COMM Radio (Garmin SL-30), because when I switch it off, the whine disappears.
How shall I eliminate this noise?
Thanks in advance
Carlos
[quote][b]
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nuckolls.bob(at)aeroelect
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| Posted: Wed Dec 31, 2008 12:04 pm Post subject: Audio noise revisited |
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At 09:03 AM 12/31/2008, you wrote:
| Quote: | To noise specialists
I just concluded the installation of my Intercom, and although I took all the recommended measures to avoid ground loops and noise in general, I'm still hearing 2 whines, which after some time (many hours … J) of investigation, I think I identified the causes.
One is the Air/Fuel Ratio Monitor, because when I disconnect its ground wire, the most high-frequency whine disappears.
Which kind of filter (resistor, capacitor, diode, any other) can I install to eliminate this noise?
And should I put it in the power(+) red wire or the ground(-) black wire, or is it indifferent?
The other whine is from the COMM Radio (Garmin SL-30), because when I switch it off, the whine disappears.
How shall I eliminate this noise? |
Have you tried running the intercom from a separate battery?
Rather than attack two noise sources, perhaps it's easier
to attack the noise propagation path for one victim.
The fact that you're hearing noise from TWO sources is
a strong suggestion that the victim is the "sub standard"
appliance with respect to tolerating noises that are
known to exist on the bus.
See if the intercom cleans up with its own separate
power source . . .
What is the input voltage range for normal operation
of your intercom?
Bob . . .
-----------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------- [quote][b]
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trigo(at)mail.telepac.pt
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| Posted: Wed Dec 31, 2008 12:39 pm Post subject: Audio noise revisited |
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Hi Bob
My Intercom is the Flightcom 403. Its power requirement (per the manual) is 12-28V 0,16Amp.
My next step would be exactly powering it from a separate battery, but I still didn’t do it, ‘cause I had no battery available - will do it next year J(tomorrow)
If it cleans up working from a separate power source, how should I proceed?
Thanks
Carlos
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III
Sent: quarta-feira, 31 de Dezembro de 2008 20:04
To: aeroelectric-list(at)matronics.com
Subject: Re: AeroElectric-List: Audio noise revisited
At 09:03 AM 12/31/2008, you wrote:
To noise specialists
I just concluded the installation of my Intercom, and although I took all the recommended measures to avoid ground loops and noise in general, I'm still hearing 2 whines, which after some time (many hours … J) of investigation, I think I identified the causes.
One is the Air/Fuel Ratio Monitor, because when I disconnect its ground wire, the most high-frequency whine disappears.
Which kind of filter (resistor, capacitor, diode, any other) can I install to eliminate this noise?
And should I put it in the power(+) red wire or the ground(-) black wire, or is it indifferent?
The other whine is from the COMM Radio (Garmin SL-30), because when I switch it off, the whine disappears.
How shall I eliminate this noise?
Have you tried running the intercom from a separate battery?
Rather than attack two noise sources, perhaps it's easier
to attack the noise propagation path for one victim.
The fact that you're hearing noise from TWO sources is
a strong suggestion that the victim is the "sub standard"
appliance with respect to tolerating noises that are
known to exist on the bus.
See if the intercom cleans up with its own separate
power source . . .
What is the input voltage range for normal operation
of your intercom?
Bob . . .
-----------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------- | Quote: | | http://www.matronics.com/contribution |
01234567890123
[quote][b]
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Wed Dec 31, 2008 1:44 pm Post subject: Audio noise revisited |
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At 02:36 PM 12/31/2008, you wrote:
| Quote: | Hi Bob
My Intercom is the Flightcom 403. Its power requirement (per the manual) is 12-28V 0,16Amp.
My next step would be exactly powering it from a separate battery, but I still didn’t do it, ‘cause I had no battery available - will do it next year J (tomorrow)
If it cleans up working from a separate power source, how should I proceed? |
Consider some form of filter for the +12V input
to the intercom. I have one I can send you to try.
See:
http://www.aeroelectric.com/Catalog/AEC/9006/9006_1.jpg
You can choose from either a horizontal or vertical
connector position.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
[quote][b]
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trigo(at)mail.telepac.pt
Guest
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| Posted: Fri Jan 02, 2009 4:22 am Post subject: Audio noise revisited |
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Bob
Did you get my offline email?
Carlos
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III
Sent: quarta-feira, 31 de Dezembro de 2008 21:43
To: aeroelectric-list(at)matronics.com
Subject: RE: AeroElectric-List: Audio noise revisited
At 02:36 PM 12/31/2008, you wrote:
Hi Bob
My Intercom is the Flightcom 403. Its power requirement (per the manual) is 12-28V 0,16Amp.
My next step would be exactly powering it from a separate battery, but I still didnt do it, cause I had no battery available - will do it next year J (tomorrow)
If it cleans up working from a separate power source, how should I proceed?
Consider some form of filter for the +12V input
to the intercom. I have one I can send you to try.
See:
http://www.aeroelectric.com/Catalog/AEC/9006/9006_1.jpg
You can choose from either a horizontal or vertical
connector position.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
--------------------------------------- | Quote: | | http://www.matronics.com/contribution |
01234567890123
[quote][b]
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Fri Jan 02, 2009 6:27 am Post subject: Audio noise revisited |
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At 07:57 AM 1/1/2009, you wrote:
| Quote: | Good morning Bob
Thanks for your offer, I accept it and I prefer the vertical connector.
Please ship it (Global Priority Mail) to
CARLOS TRIGO
Rua dos Cravos, 424
2750-225 CASCAIS
PORTUGAL
Tell me if I have to pay you something and how.
Regards
Carlos
|
We need to do the stand-alone battery test to
make sure the offending noise is coming in through
the power supply. If the noise is coming in through
another path, then a power filter wont help.
You can use a couple of 6v volt lantern batteries
in series. Do your stores carry these?
[img]cid:7.1.0.9.0.20090102080952.01ed7d50(at)aeroelectric.com.0[/img]
It doesn't need to be alkaline. The venerable old
carbon-zinc versions (cheapest) would suffice for
this task.
Bob. . .
| | - 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:
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trigo(at)mail.telepac.pt
Guest
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| Posted: Fri Jan 02, 2009 1:48 pm Post subject: Audio noise revisited |
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Ok, I sneaked out the 12V battery of my house alarm and did the test.
I powered the Intercom from that separate battery but the noises are still there. I suppose, as you say, that a filter on the Intercom power wire won’t solve my problem.
Regarding the A/F Ratio Monitor, I am pretty sure it makes one of the whines, so I have to put back the power filter that it used to have (the filter has gone west some time ago, way before installing the Intercom, and I took it away, to restore power to the Monitor, not knowing about the noise it causes). I believe that will eliminate that noise.
The remaining problem now is coming from the COMM Radio. That other whine comes on and off whenever I turn the radio on and off. I even tried powering the radio from a separate battery and no joy.
Should I put the filter on the Radio’s power line?
What do you suggest?
Carlos
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III
Sent: sexta-feira, 2 de Janeiro de 2009 14:25
To: aeroelectric-list(at)matronics.com
Subject: RE: AeroElectric-List: Audio noise revisited
At 07:57 AM 1/1/2009, you wrote:
We need to do the stand-alone battery test to
make sure the offending noise is coming in through
the power supply. If the noise is coming in through
another path, then a power filter wont help.
You can use a couple of 6v volt lantern batteries
in series. Do your stores carry these?
It doesn't need to be alkaline. The venerable old
carbon-zinc versions (cheapest) would suffice for
this task.
Bob. . .
[quote][b]
| | - 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 |
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Fri Jan 02, 2009 7:08 pm Post subject: Audio noise revisited |
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At 03:46 PM 1/2/2009, you wrote:
| Quote: | Ok, I sneaked out the 12V battery of my house alarm and did the test.
I powered the Intercom from that separate battery but the noises are still there. I suppose, as you say, that a filter on the Intercom power wire won’t solve my problem.
|
That would be my considered assessment.
| Quote: | | Regarding the A/F Ratio Monitor, I am pretty sure it makes one of the whines, so I have to put back the power filter that it used to have (the filter has gone west some time ago, way before installing the Intercom, and I took it away, to restore power to the Monitor, not knowing about the noise it causes). I believe that will eliminate that noise. |
Good experiment. Do one thing at a time so you
don't hide the results of a non-useful action.
| Quote: |
The remaining problem now is coming from the COMM Radio. That other whine comes on and off whenever I turn the radio on and off. I even tried powering the radio from a separate battery and no joy. |
When are you hearing these noises. Is the engine
running and all volume controls set for normal
operation?
| Quote: | Should I put the filter on the Radio’s power line?
What do you suggest? |
I can tell you that many a $14m airplane has some
noises in the headphones when sitting on the ground,
engines off and volume controls turned up. The
significance for most if not all these "undesirables"
goes away in flight.
Are you certain that what you're hearing really
NEEDS to be eliminated?
Bob . . .
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
[quote][b]
| | - 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 |
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