Today's Message Index:
----------------------
1. 08:18 AM - Re: voltage drop calulations (academic exercise) (Ron Quillin)
2. 08:46 AM - Re: voltage drop calulations (academic exercise) (Robert L. Nuckolls, III)
3. 10:14 AM - Re: [OT] boat wiring specificity (frazitl)
4. 10:47 AM - Re: Noisy Turn Coordinator (John McMahon)
5. 10:50 AM - (Bill Lamb)
6. 10:52 AM - TVS Failures ()
7. 04:52 PM - Re: TVS Failures (Henador Titzoff)
8. 05:14 PM - Re: voltage drop calulations (academic exercise) (raymondj)
9. 06:24 PM - Question about panel light dimmers (Neil Clayton)
10. 07:09 PM - Re: TVS Failures (Robert L. Nuckolls, III)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: voltage drop calulations (academic exercise) |
Exactly.
At 23:41 2/26/2008, you wrote:
>Ron,
>
> So, the circuit is functionally 3 resistors in series and the
> middle resistor (load) can only see the voltage drop across it as
> part of the total voltage drop in the entire circuit. If that's
> correct than I understand.
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: voltage drop calulations (academic exercise) |
At 01:41 AM 2/27/2008 -0600, you wrote:
>
>Ron,
>
> So, the circuit is functionally 3 resistors in series and the middle
> resistor (load) can only see the voltage drop across it as part of the
> total voltage drop in the entire circuit. If that's correct than I understand.
>
>Thanks for the explanation.
>Raymond Julian
>Kettle River, MN
Getting closer. There are LOTS of resistors. EVERY conductor
(including the aiframe), every compoent (terminals, studs,
contacts) and every joint between those conductors cannot
have zero resistance. We'll, we could wish for a super-
conducting system but it won't happen in our lifetimes.
See:
http://www.aeroelectric.com/Pictures/Schematics/Voltage_Drop_Study_1.pdf
http://www.aeroelectric.com/Pictures/Schematics/Voltage_Drop_Study_2.pdf
These are two studies of total resistance voltage drop
in exemplar situations. In both cases, the lower
conductor in the figure could be a wire (composite
airframe) or it could be the airframe itself. No matter
how the loop is closed to keep all the electrons moving
there will be some losses. Fortunately, most metalic
airframes are pretty good conductors. I think a Beechjet
offers something like 0.001 ohms from nose to tail.
Being a "good" conductor might allow us to ignore
the effects as tiny compared to the other conductors
but "good" is never zero.
Bob . . .
Message 3
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: [OT] boat wiring specificity |
On 2-26 you wrote:
"I've been considering switching to RG batteries in my sailboat. Batteries are
used for all power and the engine isn't run very often. There is a power charger
used in harbor. The lead acid batteries go 3-4 days without recharge. Would
RG do better? The conventional batteries are just auto batteries - supposedly
deep cycle. Would I need the same size RG batteries?"
I have no experience with sail boats. but lots of motor home experience. The hot
set-up for motorhomes is AGM battery technology. About twice as expensive,
but no fumes, no mess, better deep cycle performance, and about twice the life.
I'm about to buy new batteries for my motorhome and am going with AGMs
--------
Terry Frazier
RV7A
Finishing
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=166598#166598
Message 4
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Noisy Turn Coordinator |
Hi 'Old Bob",
I chuckle every time you get this in! I to, am a firm proponent of the turn
needle! To me it is a direct reading instrument whereas every time I fly
with a turn coordinator I have to convert everything its trying to tell me!
Could be a function of our age.... Aviation Cadet 60B......
Old John
<snip> In fact, I highly recommend that the Turn Coordinator be scrapped in
> lieu of a Turn Needle, but that is another subject!
>
> Happy Skies,
>
> Old Bob <snip>
>
>
--
John McMahon
Lancair Super ES, S/N 170, N9637M (Reserved)
Message 5
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Talk about a bored chef!
Pretty amazing.
-------------------------------------------------------------------------
-----
Message 6
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
2/27/2008
Hello Fellow Builders, The certificated airplane community has been hit with
a series of TVS failures. Several different manufacturer's airplanes have
been affected.
Copied below is just one of the SAIB's that the FAA has issued on this
subject.
If your project includes TVS' you may want to further investigate -- the
same TVS manufacturer seems to be involved in all failures.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
-----------------------------------------------------
FAA
Aircraft Certification Service
SPECIAL AIRWORTHINESS
INFORMATION BULLETIN
SUBJ: Electrical Power
SAIB: CE-08-12
This is information only. Recommendations aren't mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) advises you of an
airworthiness concern on
Cirrus Design Corporation (CDC) Models SR20 and SR22 airplanes where
possible failure of a
transient voltage suppressor (TVS) may result in an increase in workload for
the pilot.
This airworthiness action has been taken after consideration of the
responses from CDC as well as
airplane owners/ operators through relevant associations and type clubs,
using the procedures found
in the Small Airplane Directorate Airworthiness Directives Manual Supplement
(Airworthiness
Concern Process Guide).
At this time, this airworthiness concern is not considered an unsafe
condition that would warrant an
airworthiness directive (AD) action under Title 14 of the Code of Federal
Regulations (14 CFR part
39).
Background
CDC notified the Federal Aviation Administration of the failure of a TVS on
a CDC Model SR22
airplane, which resulted in loss of NAV/COM1 functionality and some smoke
and fumes within the
cockpit. Since that time, 14 other TVS's have failed on CDC airplanes in the
field.
Other airplanes equipped with TVSs from the same manufacturer have recently
experienced failures.
Our findings thus far, show that the electronic component itself is the
primary suspect for a cause of
the failures. To date, no specific reason has been positively identified for
the failures although several
companies are working on the problem.
As previously mentioned, no other functionality other than the NAV/COMM 1
has been lost on a
CDC airplane. All CDC airplanes have redundancy with a NAV/COMM 2 available.
Also, in all
known occurrences of TVS failures, the smoke and fumes have been noted to be
of short duration and
not sufficient to impede the pilots visibility, or toxic such that the pilot's
ability to operate the
airplane is impaired.
Recommendations
We recommend that all CDC airplane owner/operators thoroughly read Cirrus
service advisory SA
07-17, dated September 11, 2007. The service advisory provides good
information on what to expect
should a TVS failure occur and what actions should be taken by the pilot.
For Further Information Contact
Wesley Rouse, Aerospace Engineer, FAA Chicago Aircraft Certification, 2300
E. Devon, Des
Plaines, IL 60018; phone: (847) 294-8113; email: wess.rouse@faa.gov
Message 7
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: TVS Failures |
Bob,
Without calling the FAA, you wouldn't happen to know how to get the failed TVS
vendor's name, would you? The CDC website of course has no bad news in it. I'm
sure the vendor isn't advertising it, either.
Thanks,
Henador Titzof
----- Original Message ----
From: "bakerocb@cox.net" <bakerocb@cox.net>
Sent: Wednesday, February 27, 2008 1:49:42 PM
Subject: AeroElectric-List: TVS Failures
2/27/2008
Hello Fellow Builders, The certificated airplane community has been hit with
a series of TVS failures. Several different manufacturer's airplanes have
been affected.
Copied below is just one of the SAIB's that the FAA has issued on this
subject.
If your project includes TVS' you may want to further investigate -- the
same TVS manufacturer seems to be involved in all failures.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
Never miss a thing. Make Yahoo your home page.
http://www.yahoo.com/r/hs
Message 8
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: voltage drop calulations (academic exercise) |
I got this piece of the puzzle now. Thanks!
Raymond Julian
Kettle River, MN
"Hope for the best,
but prepare for the worst."
do not archive
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@cox.net>
Sent: Wednesday, February 27, 2008 10:42 AM
Subject: Re: AeroElectric-List: voltage drop calulations (academic exercise)
> <nuckolls.bob@cox.net>
>
> At 01:41 AM 2/27/2008 -0600, you wrote:
>
>><raymondj@frontiernet.net>
>>
>>Ron,
>>
>> So, the circuit is functionally 3 resistors in series and the middle
>> resistor (load) can only see the voltage drop across it as part of the
>> total voltage drop in the entire circuit. If that's correct than I
>> understand.
>>
>>Thanks for the explanation.
>>Raymond Julian
>>Kettle River, MN
>
> Getting closer. There are LOTS of resistors. EVERY conductor
> (including the aiframe), every compoent (terminals, studs,
> contacts) and every joint between those conductors cannot
> have zero resistance. We'll, we could wish for a super-
> conducting system but it won't happen in our lifetimes.
>
> See:
>
> http://www.aeroelectric.com/Pictures/Schematics/Voltage_Drop_Study_1.pdf
>
> http://www.aeroelectric.com/Pictures/Schematics/Voltage_Drop_Study_2.pdf
>
> These are two studies of total resistance voltage drop
> in exemplar situations. In both cases, the lower
> conductor in the figure could be a wire (composite
> airframe) or it could be the airframe itself. No matter
> how the loop is closed to keep all the electrons moving
> there will be some losses. Fortunately, most metalic
> airframes are pretty good conductors. I think a Beechjet
> offers something like 0.001 ohms from nose to tail.
> Being a "good" conductor might allow us to ignore
> the effects as tiny compared to the other conductors
> but "good" is never zero.
>
> Bob . . .
>
>
> --
> 269.21.1/1301 - Release Date: 2/27/2008 8:35 AM
>
>
Message 9
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Question about panel light dimmers |
The panel dimmer I selected can handle 1.5 amps.
I have 9 gauges needing 0.2 amps each.
So at max dimming, the dimmer is being asked to dissipate (0.2 x 9 =)
1.8 amps - a bit more than it's rated capacity.
I figured that was close enough - until I realized I forgot to
include the radio back light, which takes me WAY over the 1.5 amp capacity.
Theory; this humble M.Eng assumed the dimmer uses a
silicon-controlled rectifier that gets hotter the more it's being
asked to dim (so that for zero dimming = full brightness, there's no
heat being dissipated by the SCR's heat sink). But then I recalled
that SCR's work by clipping the tops of the current wave - except we
use 12v DC. No current curve to clip. So much for that theory!
So....how does a DC dimmer work?
Can I safely go over the rated capacity of my dimmer with no
expectation of disaster?
If a disaster were to occur, what form would it take?
Many thanks to any EE who'll take a moment to set this tyro straight.
Neil
Message 10
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: TVS Failures |
At 04:49 PM 2/27/2008 -0800, you wrote:
><henador_titzoff@yahoo.com>
>
>Bob,
>
>Without calling the FAA, you wouldn't happen to know how to get the failed
>TVS vendor's name, would you? The CDC website of course has no bad news
>in it. I'm sure the vendor isn't advertising it, either.
>
>Thanks,
>Henador Titzof
It's just a guess at this stage of the game but
I'll bet that the "problem" has more to do with
how the devices were incorporated into the system
along with sizes selected than it has to do with
quality issues for the manufacturer of the devices.
These are legacy products now . . . i.e. 20+ years
old. The manufacturer has made millions of these things
for industrial and consumer applications and is now
probably lamenting the fact that some "kind soul"
included a part of their manufacture on the BOM
of a T/C aircraft.
I won't endeavor to sell to T/C aviation and it
has nothing to do with my willingness or ability
to deliver product that meets the data sheets.
It's cases like this where a hand full of jelly-bean
parts are named participants in a "official
investigation". NOBODY wins in these things, even
if the TVS manufacturer is found blameless.
I'll see if I can find out more details. I'm
involved in some development programs for the
OEM and have some friendly contacts. In the mean
time, don't get excited about purging your
airframe of "bad parts" until we know the
physics of the matter.
Oh yeah, I'll mention in passing that my drawings
seldom if ever show a TVS as part of ship's
wiring. These things belong inside an appliance
designed and tested to meed DO-160 cert levels.
Once the appliances are pronounced golden, there's
little if any need for the wire-slingers to add
them to the system.
Bob . . .
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|