Today's Message Index:
----------------------
1. 05:54 AM - Re: strobe whine noise (Ken)
2. 08:10 AM - Re: P-Lead Routing (Robert L. Nuckolls, III)
3. 08:14 AM - Re: Loss of essential bus (Robert L. Nuckolls, III)
4. 02:45 PM - Rotax Voltage Regulator (Guy Buchanan)
5. 03:31 PM - Coax Diameter (Emrath)
6. 04:55 PM - Re: Rotax Voltage Regulator (jetboy)
7. 05:50 PM - Re: Coax Diameter (Ken)
8. 06:35 PM - Re: Re: Rotax Voltage Regulator (Guy Buchanan)
9. 08:45 PM - Re: Headset plug polarity (Fiveonepw@aol.com)
10. 10:31 PM - Re: Re: Rotax Voltage Regulator (Robert L. Nuckolls, III)
11. 10:32 PM - Re: strobe whine noise (Robert L. Nuckolls, III)
12. 10:34 PM - Re: B&C SD 8 Alternator (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: strobe whine noise |
Hi Frank
Yes the filter is in line with the strobe power after the power switch.
My best theory is similar to Matt's and that the noise is coming in via
the common grounds. It is a metal airframe and the strobe power
supplies are internally grounded to their metal cases, same as the
radio and the intercom. The headphone jacks are isolated from ground.
Everything except the strobes has a ground wire to the forrest of tabs
on the firewall. Since the ground connection on the filter has no
effect, it seems to me that it can't be a capacitor in the filter that
is helping. And yet reversing the filter leads does make a difference
which seems an unlikely result to me. I don't think there can be
anything else other than a choke (inductor) in the filter??
If I was still building I think I would try electrically insulating the
strobe power supplies from the airframe with plastic washers and bolts.
I seem to recall opening the aeroflash units when I installed them but I
must have decided that their grounds could not be easilly separated from
the case, or it did not seem worth the effort at the time. The strobe
heads are mounted in fibreglass wingtips so they should already be
isolated from the airframe.
Ken
Matt Prather wrote:
>
>When tackling a noise problem, it sometimes makes sense to clean up the
>victim, but sometimes it also works to clean up the noise source. In this
>case, it sounds like the transient current load presented by the strobes
>was causing noise to be added to the audio signal of the comm system
>(ground/supply noise). Adding a filter to the strobe circuit likely
>reduced the transient load on the bus, decreasing the noise signal seen by
>the audio system.
>
>Wiring a power supply filter depends on the components in the filter. If
>it is just a choke (coil - inductance), in-line works. If it's a 2nd (or
>higher) order filter - has a cap, the filter will need to be both inline
>and have a connection to ground.
>
>
>Regards,
>
>Matt-
>
>
>
>>Hi Ken
>>
>>How and where did you insert the filter into the 12V feed to the strobes?
>>Sounds like you inserted it 'in line' to the strobes.
>>
>>Its interesting you inserted the filter before the strobes and yet it
>>reduced the interference in your radio. How do you explain that?
>>
>> - Frank
>>
>>________________________________
>>
>>From: owner-aeroelectric-list-server@matronics.com on behalf of Ken
>>Sent: Thu 16/08/2007 14:45
>>To: aeroelectric-list@matronics.com
>>Subject: AeroElectric-List: strobe whine noise
>>
>>
>>
>>
>>FWIW powering my strobes from separate batteries made no difference to
>>the audio whine that I was hearing from them. Adding some homemade
>>filter devices likewise had no effect so I guess I did not hit on the
>>best component values. I never did find a ground issue that I could
>>blame the problem on. And yet when I finally obtained and tried a cheap
>>automotive filter on the 12 volt feed to the strobes, the situation
>>improved markedly and I can no longer hear the strobes in flight. The
>>directions said to try reversing the filter leads for best effect. Sure
>>enough the filter only worked well in one direction. Grounding the
>>ground connection to the filter also had no effect.
>>Ken
>>
>>
>>
>>>snip
>>>Bob often recommends powering from a separate battery the piece(s) of
>>>equipment that are involved in the problem. A couple of lantern
>>>batteries
>>>could be used to power the radio while the engine is running.. If that
>>>has any effect on the noise, it indicates that the problem is conducted
>>>to
>>>the radio via the power bus. Tried that from a separate 12V battery - no
>>>effect
>>>
>>>
>>>
>>>
>>snip
>>
>>
Message 2
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| Subject: | Re: P-Lead Routing |
At 04:30 PM 8/16/2007 -0700, you wrote:
>Is it an acceptable practice to route P-Leads trough the firewall
>alongside other power supply cables? I read somewhere (Tony Bingelis
>Books, I think) that shielded cables should not run alongside other cables.
>
>
The reason they are shielded is so that you CAN route
them with other cables. However, be sure to ground shield
at one end only (engine end) and use the shieled to PROVIDE
GROUND at the switch end as illustrated in numerous z-figures.
Bob . . .
Message 3
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| Subject: | Re: Loss of essential bus |
At 05:14 PM 8/16/2007 -0300, you wrote:
>I have an intermittent loss of the essential bus in my RV-8. I have wired
>it similar to Bob's Z-11 Generic Light Aircraft Electrical System except
>that I have added an aux battery as depicted in his Z-30 diagram, as I
>have dual electronic ignition. I suspect that the problem is in the diode
>that prevents reverse current when the essential bus alternate feed switch
>is turned on. My question: Is it possible that this diode is defective
>and could cause intermittent loss of the essential bus?
I've never seen a diode go intermittently open . . .
but that doesn't mean it absolutely cannot happen
however it's hard to imagine how.
> When it occurs, the current is almost immediately restored without any
> action on my part, but it does cause all the avionics to reboot. It
> occurs without warning and I cannot trust it in IFR conditions. Any
> suggestions? Thanks.
I'd suspect a loose connection first. There's not
many. Check them all. As long as your crawling around
under there . . . you could consider replacing both
wires (fresh crimps) and a new diode. In any case,
the problem cannot be terribly difficult, it doesn't
involved much hardware.
Bob . . .
Message 4
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| Subject: | Rotax Voltage Regulator |
All,
It looks like my Rotax 582 three phase voltage regulator's
dying. (It will occasionally go over voltage. I can re-set it and get
it to work, but it's happening more often now.)
Does anyone have a recommended replacement? I've mounted it
in the engine compartment to minimize electrical noise in the cockpit
and I suspect things are a little hot for the stock Rotax unit. Has
anyone tried any of the Harley replacements? Any after-market units?
Or should I just increase the cooling to the Rotax unit?
Thanks,
Guy Buchanan
San Diego, CA
K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.
Message 5
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Can someone advise me what is the diameter of RG400 and RG58 Coax? I'm
planning antenna runs for my RV6A and looking to see how big my wire bundle
may be getting. Thanks.
Marty in Brentwood TN
Message 6
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| Subject: | Re: Rotax Voltage Regulator |
Guy,
Are you sure its not the battery geeting aged. regulators dont usually deteriorate
in the way you describe, but a poor internal resistance battery may bring
on the symptom.
Ralph
--------
Ralph - CH701 / 2200a
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=129762#129762
Message 7
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| Subject: | Re: Coax Diameter |
My RG-400 measures 0.195" diameter.
Emrath wrote:
>
>Can someone advise me what is the diameter of RG400 and RG58 Coax? I'm
>planning antenna runs for my RV6A and looking to see how big my wire bundle
>may be getting. Thanks.
>
>
>Marty in Brentwood TN
>
>
Message 8
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| Subject: | Re: Rotax Voltage Regulator |
At 04:53 PM 8/18/2007, you wrote:
>Are you sure its not the battery geeting aged. regulators dont
>usually deteriorate in the way you describe, but a poor internal
>resistance battery may bring on the symptom.
I'm intrigued, since this battery has been nearly dead twice and
resurrected with a BatteryMinder. I read Bob's section on regulator
failures and it seems like the over-voltage condition should be
permanent, and not intermittent. (It seems like it doesn't work when
cold, then with my switching it in and out it finally starts to
regulate the voltage. Once it's working it never quits. And if I
re-start it seems to work fine.) I'll dig into Bob's book to try to
find an easy way to check internal resistance.
Thanks,
Guy Buchanan
San Diego, CA
K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.
Message 9
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| Subject: | Re: Headset plug polarity |
In a message dated 08/17/2007 10:06:34 PM Central Daylight Time,
ceengland@bellsouth.net writes:
There isn't really any practical way to wire a stereo connector for both
stereo & mono. You can set it up with a switch, but then you're
dependent on remembering to set the switch correctly.
>>>
My understanding as well. I installed mono & stereo jacks on my plane using
a switching mono plug that ties L&R channels together when the plug is
inserted, and used a spring-loaded cover on the stereo jack with a lable stating
"Stereo Only" on it. One way to git a kitty rug!
Diagram available on AutoCAD if interested...
>From The PossumWorks in TN
Mark Phillips
http://discover.aol.com/memed/aolcom30tour
Message 10
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| Subject: | Re: Rotax Voltage Regulator |
At 06:26 PM 8/18/2007 -0700, you wrote:
>
>At 04:53 PM 8/18/2007, you wrote:
>>Are you sure its not the battery geeting aged. regulators dont usually
>>deteriorate in the way you describe, but a poor internal resistance
>>battery may bring on the symptom.
>
>I'm intrigued, since this battery has been nearly dead twice and
>resurrected with a BatteryMinder. I read Bob's section on regulator
>failures and it seems like the over-voltage condition should be permanent,
>and not intermittent. (It seems like it doesn't work when cold, then with
>my switching it in and out it finally starts to regulate the voltage. Once
>it's working it never quits. And if I re-start it seems to work fine.)
>I'll dig into Bob's book to try to find an easy way to check internal
>resistance.
>
>Thanks,
>
>
>Guy Buchanan
Intermittent voltage excursions both upward and downward
are manifestations of ageing components and/or internal
connections that have become less than the best we know
how to do.
I believe John Deere (and others) offer a 3-phase
rectifier/regulator for their 25-40 amp PM alternators.
I searched the web hoping to find some maintenance
data or at least some part numbers. No joy.
Anyone out there have some experience with the larger
3-phase PM alternator products.
I've got to visit a customer Monday on the west side
of town near a John Deere dealership. I'll see if there's
a helpful individual there who can give me more data
on the larger PM alternator systems.
Now, this is an excellent DIY project. We've explored
the inner workings of the various PM alternator rectifier/
regulators. I've taken an exemplar single phase R/R
schematic and added the SCR and diode to accommodate
a 3 phase alternator. It's posted at:
http://www.aeroelectric.com/Pictures/Schematics/3-Phase_PM_Rectifier_Regulator.gif
This is a case where the electronics are pretty
much a no-brainer but the task to be mounted and
solved is getting the heat out. Average voltage drop
in one of these regulators is 2.2 volts. So if you're
dragging 30A from a really husky alternator, the
R/R needs to get rid of 66W of heat.
This is where attention is paid to the diodes and
SCRs to use beefy devices with low thermal resistances
and then mount them in an enclosure suited for conducting
that much heat out of the box. Problems with longevity
of the PM R/R have roots more in cooling than in the
absolute ratings of the components.
For this design, I might even consider putting the
hot parts on a finned heat sink and blowing air through
the assembly. There's a wealth of 12V DC brushless
fans out there to consider. I think I'd also add
some form of temperature sensing to at least light
a warning light and allow the pilot to consider a
temporary load reduction.
Just some food for thought. As soon as the support
tools and materials for our hardwood floor project
are out of the garage, I'll get started on the alternator
drive stand . . . should be able to run some experimental
regulator/alternator combinations on the bench this fall.
Bob . . .
Message 11
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| Subject: | Re: strobe whine noise |
At 08:53 AM 8/18/2007 -0400, you wrote:
>
>Hi Frank
>
>Yes the filter is in line with the strobe power after the power switch.
>
>My best theory is similar to Matt's and that the noise is coming in via
>the common grounds. It is a metal airframe and the strobe power supplies
>are internally grounded to their metal cases, same as the radio and the
>intercom. The headphone jacks are isolated from ground. Everything except
>the strobes has a ground wire to the forrest of tabs on the firewall.
>Since the ground connection on the filter has no effect, it seems to me
>that it can't be a capacitor in the filter that is helping. And yet
>reversing the filter leads does make a difference which seems an unlikely
>result to me. I don't think there can be anything else other than a choke
>(inductor) in the filter??
>
>If I was still building I think I would try electrically insulating the
>strobe power supplies from the airframe with plastic washers and bolts. I
>seem to recall opening the aeroflash units when I installed them but I
>must have decided that their grounds could not be easilly separated from
>the case, or it did not seem worth the effort at the time. The strobe
>heads are mounted in fibreglass wingtips so they should already be
>isolated from the airframe.
Hmmmm . . . grounds contribute to noise issues ONLY when
sensitive potential victims share TWO or more ground
paths. If you have immediate access to the power supplies,
try the dry-battery experiment again with the battery located
right at the power supply and grounded locally to the power
supply.
There's something we're not seeing here. I presume that your
power supply does ground locally and doesn't have a second wire
running all the way to the firewall ground bus????
Bob . . .
Message 12
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| Subject: | Re: B&C SD 8 Alternator |
At 07:19 AM 8/16/2007 -0500, you wrote:
>
>Harley, et al,
>
>I have a friend with a Pitts who has a SD 8 as his only power source
>other than the battery. He has no electronics other than a radio and
>the starter. His SD 8 is more than adequate to run the radio with
>enough current left over to charge the battery.
>
>The only concern I would have with the SD 8 or the SD 20 as a sole
>power source is that both require fairly high RPM to produce adequate
>current for much of anything. Our usual high amp alternators produce
>enough juice at idle to charge the battery.
Which is no worse than generators used to offer. There
are hundreds of OBAM light aircraft flying with vacuum
pump driven alternator products from B&C as their sole
source of engine driven power. These are, of course,
mostly day VFR aircraft. A few night VFR too . . . but
if one had LED based position and strobes, then perhaps
night VFR on 8A would be quite comfortably managed.
It can be done now and is going to get easier in the
near future.
Bob . . .
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