Today's Message Index:
----------------------
1. 05:43 AM - Re: Interest level in RG-400 cable at discount (Jerry Grimmonpre)
2. 06:13 AM - Re: Interest level in RG-400 cable at discount (Jerry Grimmonpre)
3. 06:19 AM - Re: Power supply (Robert L. Nuckolls, III)
4. 07:00 AM - Re: Open letter to the list (Ken)
5. 07:44 AM - Re: Open letter to the list clamav-milter version 0.80j on juliet.albedo.net (George Braly)
6. 08:58 AM - Re: Load Dump (Eric M. Jones)
7. 10:03 AM - Re: Re: Load Dump (Brian Lloyd)
8. 10:24 AM - Microair 760N to Flightcom 403 (Mervin Friesen)
9. 11:26 AM - Re: Microair 760N to Flightcom 403 (Robert L. Nuckolls, III)
10. 12:39 PM - Re: Microair 760N to Flightcom 403 (Mervin Friesen)
11. 03:39 PM - Dimmer voltage (Bikcrzy@aol.com)
12. 03:46 PM - Pretty darned confused about grounding shields (Dan O'Brien)
13. 04:22 PM - P-leads and ignition wires (N67BT@aol.com)
14. 04:33 PM - Re: Pretty darned confused about grounding shields (Wayne Sweet)
15. 05:15 PM - Re: P-leads and ignition wires (Matt Prather)
16. 05:57 PM - Re: Pretty darned confused about grounding shields (rv-9a-online)
17. 06:39 PM - Re: Pretty darned confused about grounding shields (Wayne Sweet)
18. 08:24 PM - Re: Pretty darned confused about grounding shields (Dan O'Brien)
19. 09:35 PM - Re: Open letter to the list (Paul Messinger)
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: Interest level in RG-400 cable at discount |
--> AeroElectric-List message posted by: "Jerry Grimmonpre" <jerry@mc.net>
----- Original Message -----
From: "Jack" <jgh2@charter.net>
Subject: Re: AeroElectric-List: Interest level in RG-400 cable at discount
> --> AeroElectric-List message posted by: Jack <jgh2@charter.net>
>
>
> On Thursday, January 27, 2005, at 11:19 PM, SportAV8R@aol.com wrote:
>
>> I have a chance to purchase RG-400 coax in bulk, and could part out a
>> roll to builders at 1.00/foot in any length.
>
> Bill,
>
> I bought some RG-400 a few months ago at a great price and can supply
> you or others for $.50/foot plus shipping.
>
> Jack H.
> RV-6A
>
> P. S. Also have the BNC male connectors and tools to make completed
> cables but the price would be significantly higher because I'm tired of
> the "strip, crimp and shrink" routine.
>
>
>
>
>
>
>
>
>
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: Interest level in RG-400 cable at discount |
--> AeroElectric-List message posted by: "Jerry Grimmonpre" <jerry@mc.net>
Ooops! ... Sorry listers, I hit the send by mistake ... Jerry
Do not archive
----- Original Message -----
From: "Jerry Grimmonpre" <jerry@mc.net>
Subject: Re: AeroElectric-List: Interest level in RG-400 cable at discount
> --> AeroElectric-List message posted by: "Jerry Grimmonpre" <jerry@mc.net>
>
>
> ----- Original Message -----
> From: "Jack" <jgh2@charter.net>
> To: <aeroelectric-list@matronics.com>
> Subject: Re: AeroElectric-List: Interest level in RG-400 cable at discount
>
>
>> --> AeroElectric-List message posted by: Jack <jgh2@charter.net>
>>
>>
>> On Thursday, January 27, 2005, at 11:19 PM, SportAV8R@aol.com wrote:
>>
>>> I have a chance to purchase RG-400 coax in bulk, and could part out a
>>> roll to builders at 1.00/foot in any length.
>>
>> Bill,
>>
>> I bought some RG-400 a few months ago at a great price and can supply
>> you or others for $.50/foot plus shipping.
>>
>> Jack H.
>> RV-6A
>>
>> P. S. Also have the BNC male connectors and tools to make completed
>> cables but the price would be significantly higher because I'm tired of
>> the "strip, crimp and shrink" routine.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
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: Power supply |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 06:49 AM 1/28/2005 +0100, you wrote:
>--> AeroElectric-List message posted by: "John F. Herminghaus"
><catignano@tele2.it>
>
>Bob:
>
>It is normal to put more than one engine instrument on a fuse or cb ,
>but what about the power leads? Can the be daisy chained or do you
>recommend separate wires for each device?
From the perspective of electrical system safety, it's technically
SAFE to put EVERYTHING on one protected circuit as long as the downstream
wiring is properly protected. From the perspective of flight system
safety, it's best to have no single fault take down more than
the system so afflicted.
Engine instruments are VERY low on priority of aids to flight
safety so if you're short on fuse slots, those would be the FIRST
articles I'd team up on one protected circuit. It's purely
a "comfort decision" . . . big fuseblocks are readily available
and can provide for maximum isolation between systems.
Bob . . .
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: Open letter to the list |
clamav-milter version 0.80j
on juliet.albedo.net
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
May I ask what the current draw of the landing lights was? I'm having
trouble imagining that much load. I was alway taught to operate switches
one at a time. ie even if turning off a row of light switches - do it
one at a time.
My presumption has been that most old worn contactors fail to start the
engine. And that the minor contact welding caused by passing starter
current generally keeps the contacts at fairly low resistance for the
rest of the flight. Am I wrong? How do most contactors fail? Doesn't
really matter to me as I don't have battery contactors, just OV
contactors, but it's still interesting.
While I'd never do it intentionally, I've seen a couple of vehicles
continue to operate with a disconnected/open battery circuit with no
secondary problems develop. The alternator kept working. So far I've
never found a transorb hidden in any circuitry or components. I know
that is too small a sample to mean much.
How did Thielert get into that position? My philosophy has always been
redundancy for electrically dependant engines. If their redundancy was
that either the battery or the alternator would power a pump then surely
they aren't using common wiring/contactor or not testing the system with
the battery disconnected??? Maybe they should tune in here ;)
Ken
George Braly wrote:
>--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
>
>
>Bob,
>
>40 amp ND alternator.
>
>Under load at 4000 shaft RPM and 30-35 amps at 28 volts.
>
>An 11,000 uF cap on line.
>
>Load consists of landing lights - - not atypical.
>
>Kill the landing lights with no battery on the circuit, and I could repeatedly
fry 5KW transorbs rated at 36 volts.
>
>I was also frying a 5 volt switching power supply (rated to take 60 volt inputs)
on the same circuit.
>
>This was not very complicated but it was repeatable, and of course, unacceptable.
>
>By the way, this issue is a real problem. Now recognized on certified aircraft.
Recently the German FAA type folks had to issue an AD against the Thielert
125Hp diesel engine because it was failing due to electrical failure (engine
is dependant upon the electron pump) when the battery relay failed and the battery
was off line... and the regulator/alternator was self-destructing - - -
thus causing the engine to quit.
>
>Regards, George
>
>
>
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 |
|
| Subject: | Open letter to the list clamav-milter version |
0.80j on juliet.albedo.net
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
Ken,
The current draw was as stated. Yes, there were more than one landing light on
the circuit. Yes, they were disconnected more or less simultaneously.
Keep in mind, that the FAA requires that one must be able to disconnect the entire
aircraft electrical system "by the single movement of one hand."
Regards, George
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ken
Subject: Re: AeroElectric-List: Open letter to the list clamav-milter version 0.80j
on juliet.albedo.net
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
May I ask what the current draw of the landing lights was? I'm having
trouble imagining that much load. I was alway taught to operate switches
one at a time. ie even if turning off a row of light switches - do it
one at a time.
My presumption has been that most old worn contactors fail to start the
engine. And that the minor contact welding caused by passing starter
current generally keeps the contacts at fairly low resistance for the
rest of the flight. Am I wrong? How do most contactors fail? Doesn't
really matter to me as I don't have battery contactors, just OV
contactors, but it's still interesting.
While I'd never do it intentionally, I've seen a couple of vehicles
continue to operate with a disconnected/open battery circuit with no
secondary problems develop. The alternator kept working. So far I've
never found a transorb hidden in any circuitry or components. I know
that is too small a sample to mean much.
How did Thielert get into that position? My philosophy has always been
redundancy for electrically dependant engines. If their redundancy was
that either the battery or the alternator would power a pump then surely
they aren't using common wiring/contactor or not testing the system with
the battery disconnected??? Maybe they should tune in here ;)
Ken
George Braly wrote:
>--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
>
>
>Bob,
>
>40 amp ND alternator.
>
>Under load at 4000 shaft RPM and 30-35 amps at 28 volts.
>
>An 11,000 uF cap on line.
>
>Load consists of landing lights - - not atypical.
>
>Kill the landing lights with no battery on the circuit, and I could repeatedly
fry 5KW transorbs rated at 36 volts.
>
>I was also frying a 5 volt switching power supply (rated to take 60 volt inputs)
on the same circuit.
>
>This was not very complicated but it was repeatable, and of course, unacceptable.
>
>By the way, this issue is a real problem. Now recognized on certified aircraft.
Recently the German FAA type folks had to issue an AD against the Thielert
125Hp diesel engine because it was failing due to electrical failure (engine
is dependant upon the electron pump) when the battery relay failed and the battery
was off line... and the regulator/alternator was self-destructing - - -
thus causing the engine to quit.
>
>Regards, George
>
>
>
---
---
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 |
|
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
Load Dump occurs anytime the generator sheds its load (like turning
something off), because the generator/alternator has a collapsing magnetic
field. This takes a while---almost half-a-second in the worst case. Load
Dump is at it's worst when nothing but a flat battery is being honked
on by the alternator/ generator and every other load is off---THEN the
battery gets disconnected. Paul Messinger has pointed out to me that this is
what happens to the stored energy in an inductor like a relay too--just on a
smaller scale.
Let's see what's going on with George's 5kW transorbs---- (some of this
email I posted previously)
>40 amp ND alternator. Under load at 30-35 amps at 28 volts.
>An 11,000 uF cap on line.
>Load consists of landing lights.
>Kill the landing lights with no battery on the circuit, and I could
repeatedly fry 5KW transorbs rated at 36 volts.
>I was also frying a 5 volt switching power supply (rated to take 60 volt
inputs) on the same circuit.
Load dump Std Open-Circuit Volts Rise Time (10%-90%) Pulse duration
(10%-10%)
SAE J1113-11 ???? ???? ????
Chrysler PF9326 91.5 V 5-10 mS 300 mS
Ford CL240 60 V 1-10 mS 300 mS
ISO 7637 ?? 5-10 mS 50-400 mS
To properly design a system to squash this stuff we need to know the worst
case system energy (in Joules), which, we all remember, is a Watt-second.
These are hard numbers to come by, but we can tease them out of the
published data: Chrysler PF9326 presumes a Load Dump pulse of 91.5 Volts
into a 0.5 ohm load at 14 VDC, so we can presume George's 28 VDC system
(worst case) could be above even that. So the energy stored in the inductor
is 2X at twice the voltage. The energy is 1/2 L x I sqrd. Where "L" is the
inductance (proportional to the alternator windings) and "I" the current. So
we presume the inductance is twice and the current stays about the same. If
Chrysler's test number is reasonable then, the open circuit voltage must be
about 180 VDC(Yikes...it fried the power supply!)
Chrysler's assumed load impedance is 0.5 ohms, but since cars are wired
looser than airplanes, the airplane's electrical system COULD be even lower.
But we'll go with 0.5 ohms.
Peak current therefore could be 180/0.5=360 Amps. And peak watts (power) is
therefore 64.8 kW. The exponential decay is 0.300 Seconds. So that's (...are
you following this?) 64.8 kW X 0.300 S=19.4 kW seconds X 1/3 to 1/2 which
is the correction factor for the exponential decay. We get 6.5-9.7 kW. So
yes we can make a 5 kW transorb think it's the fourth of July. If we use a
10 kW device we buy a little margin. And yes I know I left out the 36V
transorb cut-off but I just count that as margin.
I don't know how the 11,000 uF cap figures into this--but I'd be
careful--because it doesn't help.
Now that you 'splained it George there is no mystery.
BTW: Aviation Consumer rated George Braly's company GAMI to be company of
the year. For a nice note on this and a good picture of George please see:
http://www.aviation-consumer.com/ytb/
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
Teamwork: " A lot of people doing exactly what I say."
(Marketing exec., Citrix Corp.)
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 |
|
--> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
Eric M. Jones wrote:
> To properly design a system to squash this stuff we need to know the worst
> case system energy (in Joules), which, we all remember, is a Watt-second.
> These are hard numbers to come by, but we can tease them out of the
> published data: Chrysler PF9326 presumes a Load Dump pulse of 91.5 Volts
> into a 0.5 ohm load at 14 VDC, so we can presume George's 28 VDC system
> (worst case) could be above even that. So the energy stored in the inductor
> is 2X at twice the voltage. The energy is 1/2 L x I sqrd.
Not quite. That would be the way to figure out how much energy is stored
in the field (armature) b-field but that is not the problem. The
residual excess magnetism in the armature is causing the alternator to
just continue generating more power than it should. The problem comes
from the excess output from the *stator* as a result of the mechanical
input (engine power turning the alternator), not the energy contained in
the armature's b-field.
When you drop the load from say 30A to 10A suddenly, the mechanical
input and field current momentarily remain the same. (The regulator
hasn't had time to reduce the field current and even if it did, it would
take time for the b-field to change to the new, lower value.) If you
were drawing 30A @ 14V (420W or a bit over 1/2 hp) and now you change to
a 10A draw, the *power* output will remain the same (momentarily, modulo
the inductance of the stator which will slow down the voltage rise time)
at 420W. But in order to get the same *power* out with a 10A current
draw the voltage must quickly rise to 42V. The voltage will then ramp
back to 14V as the field b-field collapses to a lower value and reduces
the alternator output.
This only happens if there is nothing to absorb the extra energy (like
the battery). If the battery is there it just absorbs this excess power
and it just looks like a small bump in the buss voltage. If you are
looking at battery *current* you will see a sudden rise to 20A and then
a ramp back to the quiescent float charge current at 14V (probably an
amp or so).
BTW, if the load dump were to drop the demand from 30A to 1A, the
theoretical voltage rise would be a LOT higher (on the order of 420V
everything else being equal) but then other things will start absorbing
that excess energy including the output diodes and anything else still
on the bus.
If I could see the rate at which the field current decreases and the
transfer characteristic of the alternator that shows power output as a
function of field current and RPM, I could integrate the area under the
curve to calculate the total energy that must be absorbed. But I don't
have that information and besides, I am lazy. Regardless, I am sure Paul
or Bob is doing that so I don't have to worry my pretty little head over it.
The key point here is that, if the battery is in good condition and
there is a low resistance path from the B-lead and ground of the
alternator to the battery, there is no problem with load dump. The
battery just sucks up that extra energy and no one is the wiser. If the
battery does NOT do the job, the bus voltage rises and things get fried.
--
Brian Lloyd 6501 Red Hook Plaza
brianl@lloyd.com Suite 201
http://www.lloyd.com St. Thomas, VI 00802
+1.340.998.9447 (voice) +1.270.912.0788 (fax)
There is a time to laud one's country and a time to protest.
A good citizen is prepared to do either as the need arises.
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: | Microair 760N to Flightcom 403 |
--> AeroElectric-List message posted by: "Mervin Friesen" <mefriese@hsd.ca>
This question was asked and the reply given as copied below. The response is based on the maual for revision C. The manual on the Microair site shows revision N with some pins being changed. Can someone advise how to connect the two with the latest revision? It can be found here - page 18. http://www.microair.com.au/admin/uploads/760installusermanualverN.pdf
Thank you!
Mervin Friesen
Sonex #122
Has anyone matched up the flightcom 403mc intercom to the microair 760-N
transceiver. I've received two different pinout diagrams and niether one matches
the schematics I have for the units. A working pinout diagram would sure
make me feel better before I apply power to this combo.
Referring to MC403 manual at: <http://www.flightcom.net/pdf/403mcManual.pdf> and 760VHF manual at: <http://www.aeroelectric.com/Catalog/avionics/760imB.pdf>
You connect: MC403 "Tramnsmit Key Line" to Microair Pin 7
MC403 "Receive Audio" to Microair Pin 14 MC403 "Transmit Audio" to Microair
Pin 1
MC403 "Avionics Ground" to Microair Pin 2
and eliminate the avionics ground shown just to the right of the aircraft
radio in the MC403 wiring. Ignore Micorair Pin 3, "COPILOT MIC HI" Ignore all
headphone, microphone and push to talk wiring shown on the Microair wiring
diagram including the intercom wiring to pin 5.
Bob . . .
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: | Re: Microair 760N to Flightcom 403 |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 12:23 PM 1/28/2005 -0600, you wrote:
>--> AeroElectric-List message posted by: "Mervin Friesen" <mefriese@hsd.ca>
>
>
>This question was asked and the reply given as copied below. The response
>is based on the maual for revision C. The manual on the Microair site
>shows revision N with some pins being changed.
Which pins are changed? I've compared the latest download from Microair
with what I published in our in-house generated instructions and
the pinouts from the radio appear unchanged to me.
Bob . . .
> Can someone advise how to connect the two with the latest revision? It
> can be found here - page 18.
> http://www.microair.com.au/admin/uploads/760installusermanualverN.pdf
>Thank you!
>Mervin Friesen
>Sonex #122
>Date: Jan 01, 2005
>
> Has anyone matched up the flightcom 403mc intercom to the
> microair 760-N transceiver. I've received two different pinout diagrams
> and niether one matches the schematics I have for the units. A working
> pinout diagram would sure make me feel better before I apply power to
> this combo.
> Referring to MC403 manual at:
> <http://www.flightcom.net/pdf/403mcManual.pdf> and 760VHF manual at:
> <http://www.aeroelectric.com/Catalog/avionics/760imB.pdf>
>
> You connect: MC403 "Tramnsmit Key Line" to Microair Pin 7
> MC403 "Receive Audio" to Microair Pin 14
> MC403 "Transmit Audio" to Microair Pin 1
> MC403 "Avionics Ground" to Microair Pin 2
> and eliminate the avionics ground shown just to the right of the
> aircraft radio in the MC403 wiring. Ignore Micorair Pin 3, "COPILOT MIC
> HI" Ignore all headphone, microphone and push to talk wiring shown on the
> Microair wiring diagram including the intercom wiring to pin 5.
> Bob . . .
>
>
>--
>No virus found in this incoming message.
>Checked by AVG Anti-Virus.
>Version: 7.0.300 / Virus Database: 265.7.6 - Release Date: 1/27/2005
>
>
>-- incoming mail is certified Virus Free.
>Checked by AVG Anti-Virus.
>Version: 7.0.300 / Virus Database: 265 - Release Date: 1/27/2005
Bob . . .
--------------------------------------------------------
< Throughout history, poverty is the normal condition >
< of man. Advances which permit this norm to be >
< exceeded -- here and there, now and then -- are the >
< work of an extremely small minority, frequently >
< despised, often condemned, and almost always opposed >
< by all right-thinking people. Whenever this tiny >
< minority is kept from creating, or (as sometimes >
< happens) is driven out of a society, the people >
< then slip back into abject poverty. >
< >
< This is known as "bad luck". >
< -Lazarus Long- >
<------------------------------------------------------>
http://www.aeroelectric.com
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: | Microair 760N to Flightcom 403 |
--> AeroElectric-List message posted by: "Mervin Friesen" <mefriese@hsd.ca>
I'm certainly no expert, so my observation may not be accurate. But in the instructions
copied below, it says MC403 "Avionics Ground" to Microair Pin 2. On the
Revision N diagram, pin 2 shows no internal connection. On revision C, pin
2 is labelled Mic Lo. This is what led me to my request for advice.
Thanks!
Mervin Friesen
Sonex #122
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Robert
L. Nuckolls, III
Subject: Re: AeroElectric-List: Microair 760N to Flightcom 403
Which pins are changed? I've compared the latest download from Microair
with what I published in our in-house generated instructions and
the pinouts from the radio appear unchanged to me.
Bob . . .
> Referring to MC403 manual at:
> <http://www.flightcom.net/pdf/403mcManual.pdf> and 760VHF manual at:
> <http://www.aeroelectric.com/Catalog/avionics/760imB.pdf>
>
> You connect: MC403 "Tramnsmit Key Line" to Microair Pin 7
> MC403 "Receive Audio" to Microair Pin 14
> MC403 "Transmit Audio" to Microair Pin 1
> MC403 "Avionics Ground" to Microair Pin 2
> and eliminate the avionics ground shown just to the right of the
> aircraft radio in the MC403 wiring. Ignore Micorair Pin 3, "COPILOT MIC
> HI" Ignore all headphone, microphone and push to talk wiring shown on the
> Microair wiring diagram including the intercom wiring to pin 5.
> Bob . . .
Message 11
| 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 |
|
--> AeroElectric-List message posted by: Bikcrzy@aol.com
Hello Group,
I procured a 5 amp dimmer control from B&C. When my bus voltage is 12
Volts the power lead from the dimmer with the potentiometer turned to the
brightness is a shade over 10 volts and when connected the voltage drops to a
shade under 10 volts. I ran a lead directly from the bus to the terminal blocks
where the lights are hooked up and everything reads 12 volts. Is the dimmer
control designed to only deliver 10 volts when fed 12? Is this because when
the alternated is running it will make up the difference since the buss voltage
will climb to 13.8 or so? Thanks for your thoughts. JR RV-7A Still Wiring.
Message 12
| 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: | Pretty darned confused about grounding shields |
--> AeroElectric-List message posted by: "Dan O'Brien" <danobrien@cox.net>
After Wayne Sweet suggested the Garmin manual was off regarding shielding,
I called the company. Ready for this?
1. Connecting a UPS SL30 Nav Com to a MD200-306 CDI indicator: UPS manual
(before the Garmin merger) says ground shields at both ends. They are
SPECIFIC. For example, they have footnotes that explicitly say to ground a
both ends, while they also have footnotes saying to let float the Nav/Com
end of the connection to the audio panel. Couldn't be more explicit.
However, the Garmin tech rep says to ground the shields only at the Nav/Com
end. He says "I don't know why the manual says that?
2. Connecting a GNS430 GPS/Nav/Com to a MD200-306 CDI indicator: Garmin
manual says ground shields at both ends.
However, the Garmin tech rep says to ground the shields only at the Nav/Com
end. He says "I don't know why the manual says that?
3. Connecting a GNS430 to an altitude serializer: Garmin manual says ground
the shield at both ends.
However, the Garmin tech rep says to ground the shield only at the Garmin end;
while the Microencoder rep says ground the shield at the Microencoder end
(the "sending" end).
Almost as bad as economists (my field). OK scientists, there either IS a
right answer to each question, or there are tradeoffs that are worth
understanding. Inquiring (if somewhat mystified, and a little irritated)
minds want to know.
Message 13
| 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: | P-leads and ignition wires |
--> AeroElectric-List message posted by: N67BT@aol.com
Bob and other listers,
I am running my mag P-leads separate from my other circuits. I would like
to bundle these though with the ignition wires for about 18" to keep things
neat in the engine compartment. Will that cause any kind of problem?
Thanks,
Bob Trumpfheller
RV7A / Lycoming IO360
http://users.aol.com/n67bt
Message 14
| 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: Pretty darned confused about grounding shields |
--> AeroElectric-List message posted by: "Wayne Sweet" <w_sweet@comcast.net>
Ahh...... electronics apparently really is a black art, one that only
'nature' has the final say; If it works, then it's correct. Don't fool with
"mother nature". Problem is she ain't talking.
Wayne
----- Original Message -----
From: "Dan O'Brien" <danobrien@cox.net>
Subject: AeroElectric-List: Pretty darned confused about grounding shields
> --> AeroElectric-List message posted by: "Dan O'Brien" <danobrien@cox.net>
>
> After Wayne Sweet suggested the Garmin manual was off regarding shielding,
> I called the company. Ready for this?
>
> 1. Connecting a UPS SL30 Nav Com to a MD200-306 CDI indicator: UPS manual
> (before the Garmin merger) says ground shields at both ends. They are
> SPECIFIC. For example, they have footnotes that explicitly say to ground
> a
> both ends, while they also have footnotes saying to let float the Nav/Com
> end of the connection to the audio panel. Couldn't be more explicit.
> However, the Garmin tech rep says to ground the shields only at the
> Nav/Com
> end. He says "I don't know why the manual says that?
> 2. Connecting a GNS430 GPS/Nav/Com to a MD200-306 CDI indicator: Garmin
> manual says ground shields at both ends.
> However, the Garmin tech rep says to ground the shields only at the
> Nav/Com
> end. He says "I don't know why the manual says that?
> 3. Connecting a GNS430 to an altitude serializer: Garmin manual says
> ground
> the shield at both ends.
> However, the Garmin tech rep says to ground the shield only at the Garmin
> end;
> while the Microencoder rep says ground the shield at the Microencoder end
> (the "sending" end).
>
> Almost as bad as economists (my field). OK scientists, there either IS a
> right answer to each question, or there are tradeoffs that are worth
> understanding. Inquiring (if somewhat mystified, and a little irritated)
> minds want to know.
>
>
>
I am using the free version of SPAMfighter for private users.
It has removed 701 spam emails to date.
Paying users do not have this message in their emails.
Try www.SPAMfighter.com for free now!
Message 15
| 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: P-leads and ignition wires |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
I think it unlikely to cause problems.. Noise from the P-lead to the
high tension isn't a concern. Noise from the high tension to the P-lead
is unlikely since both wires are shielded. Even a broken shield on one
or the other isn't likely to be an issue. Any noise the high tension lead
puts onto the P-lead is going to be much lower than the P-lead operating
voltage. I could imagine there being a slight chance of this added noice
confusing a digital tach which looks at the P-lead.
Matt-
> --> AeroElectric-List message posted by: N67BT@aol.com
>
> Bob and other listers,
>
> I am running my mag P-leads separate from my other circuits. I would
> like to bundle these though with the ignition wires for about 18" to
> keep things neat in the engine compartment. Will that cause any kind
> of problem?
>
> Thanks,
>
> Bob Trumpfheller
>
> RV7A / Lycoming IO360
>
> http://users.aol.com/n67bt
>
>
Message 16
| 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: Pretty darned confused about grounding shields |
--> AeroElectric-List message posted by: rv-9a-online <rv-9a-online@telus.net>
OK, lots of confusing facts.
The purpose of a shield is to prevent outside interference or,
conversely, to prevent the signal from radiating interference. You'd
think that grounding both ends would be OK, but then we have an
interesting effect:
It's possible when grounding both ends, for current to flow in the
shield and through the equipment grounds. This current is caused by the
ever-present difference in ground voltages within each of the equipment
due to internal loads and wire lengths, etc.
When this occurs, high frequency longitudinal currents may flow in the
shield. This makes a good antenna, radiating energy around it, and
especially into the wire it's supposed to shield. The best way to
prevent this current flow is to not connect one end. Most of the
benefit will be gained by only connecting one end, and it does not
matter which end.
There is a theoretical additional benefit by ground the 'transmitter'
end (if you can figure this out) rather than the 'receiver' end, simply
because any noise in the transmitter ground should also be superimposed
on the transmitter signal, thus minimizing the (presumably noisy)
metallic currents (currents from signal to shield). This may slightly
reduce radiated interference.
Some think that it's better to ground only the audio panel/intercom end
of audio signals because that represents the system 'quiet point'. This
makes sense. A true quiet ground shield won't be radiating anything,
whereas a high power comm might have some ground bounce.
So, rules of thumb:
1) Don't ground both ends of a shield.
2) If not specified, ground the transmitter end only (most signals other
than audio signals); except
3) For audio signals, ground the audio panel end only.
I can't comment on Garmin's confusing documentation, except that the
tech rep is probably right. The engineer (blush) that wrote the Garmin
documentation is probably related to the guy who made Garmin avionics
trays 6.3125" wide rather than the 6.25" the rest of the civilized world
standardized on.
Vern Little, RV-9A
Dan O'Brien wrote:
>--> AeroElectric-List message posted by: "Dan O'Brien" <danobrien@cox.net>
>
>After Wayne Sweet suggested the Garmin manual was off regarding shielding,
>I called the company. Ready for this?
>
>1. Connecting a UPS SL30 Nav Com to a MD200-306 CDI indicator: UPS manual
>(before the Garmin merger) says ground shields at both ends. They are
>SPECIFIC. For example, they have footnotes that explicitly say to ground a
>both ends, while they also have footnotes saying to let float the Nav/Com
>end of the connection to the audio panel. Couldn't be more explicit.
>However, the Garmin tech rep says to ground the shields only at the Nav/Com
>end. He says "I don't know why the manual says that?
>2. Connecting a GNS430 GPS/Nav/Com to a MD200-306 CDI indicator: Garmin
>manual says ground shields at both ends.
>However, the Garmin tech rep says to ground the shields only at the Nav/Com
>end. He says "I don't know why the manual says that?
>3. Connecting a GNS430 to an altitude serializer: Garmin manual says ground
>the shield at both ends.
>However, the Garmin tech rep says to ground the shield only at the Garmin end;
>while the Microencoder rep says ground the shield at the Microencoder end
>(the "sending" end).
>
>Almost as bad as economists (my field). OK scientists, there either IS a
>right answer to each question, or there are tradeoffs that are worth
>understanding. Inquiring (if somewhat mystified, and a little irritated)
>minds want to know.
>
>
>
>
Message 17
| 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: Pretty darned confused about grounding shields |
--> AeroElectric-List message posted by: "Wayne Sweet" <w_sweet@comcast.net>
This is a keeper...........
Into my avionics folder goes this one.
Wayne
----- Original Message -----
From: "rv-9a-online" <rv-9a-online@telus.net>
Subject: Re: AeroElectric-List: Pretty darned confused about grounding
shields
> --> AeroElectric-List message posted by: rv-9a-online
> <rv-9a-online@telus.net>
>
> OK, lots of confusing facts.
>
> The purpose of a shield is to prevent outside interference or,
> conversely, to prevent the signal from radiating interference. You'd
> think that grounding both ends would be OK, but then we have an
> interesting effect:
>
> It's possible when grounding both ends, for current to flow in the
> shield and through the equipment grounds. This current is caused by the
> ever-present difference in ground voltages within each of the equipment
> due to internal loads and wire lengths, etc.
>
> When this occurs, high frequency longitudinal currents may flow in the
> shield. This makes a good antenna, radiating energy around it, and
> especially into the wire it's supposed to shield. The best way to
> prevent this current flow is to not connect one end. Most of the
> benefit will be gained by only connecting one end, and it does not
> matter which end.
>
> There is a theoretical additional benefit by ground the 'transmitter'
> end (if you can figure this out) rather than the 'receiver' end, simply
> because any noise in the transmitter ground should also be superimposed
> on the transmitter signal, thus minimizing the (presumably noisy)
> metallic currents (currents from signal to shield). This may slightly
> reduce radiated interference.
>
> Some think that it's better to ground only the audio panel/intercom end
> of audio signals because that represents the system 'quiet point'. This
> makes sense. A true quiet ground shield won't be radiating anything,
> whereas a high power comm might have some ground bounce.
>
> So, rules of thumb:
>
> 1) Don't ground both ends of a shield.
> 2) If not specified, ground the transmitter end only (most signals other
> than audio signals); except
> 3) For audio signals, ground the audio panel end only.
>
> I can't comment on Garmin's confusing documentation, except that the
> tech rep is probably right. The engineer (blush) that wrote the Garmin
> documentation is probably related to the guy who made Garmin avionics
> trays 6.3125" wide rather than the 6.25" the rest of the civilized world
> standardized on.
>
> Vern Little, RV-9A
>
>
> Dan O'Brien wrote:
>
>>--> AeroElectric-List message posted by: "Dan O'Brien" <danobrien@cox.net>
>>
>>After Wayne Sweet suggested the Garmin manual was off regarding shielding,
>>I called the company. Ready for this?
>>
>>1. Connecting a UPS SL30 Nav Com to a MD200-306 CDI indicator: UPS manual
>>(before the Garmin merger) says ground shields at both ends. They are
>>SPECIFIC. For example, they have footnotes that explicitly say to ground
>>a
>>both ends, while they also have footnotes saying to let float the Nav/Com
>>end of the connection to the audio panel. Couldn't be more explicit.
>>However, the Garmin tech rep says to ground the shields only at the
>>Nav/Com
>>end. He says "I don't know why the manual says that?
>>2. Connecting a GNS430 GPS/Nav/Com to a MD200-306 CDI indicator: Garmin
>>manual says ground shields at both ends.
>>However, the Garmin tech rep says to ground the shields only at the
>>Nav/Com
>>end. He says "I don't know why the manual says that?
>>3. Connecting a GNS430 to an altitude serializer: Garmin manual says
>>ground
>>the shield at both ends.
>>However, the Garmin tech rep says to ground the shield only at the Garmin
>>end;
>>while the Microencoder rep says ground the shield at the Microencoder end
>>(the "sending" end).
>>
>>Almost as bad as economists (my field). OK scientists, there either IS a
>>right answer to each question, or there are tradeoffs that are worth
>>understanding. Inquiring (if somewhat mystified, and a little irritated)
>>minds want to know.
>>
>>
>>
>>
>
>
>
I am using the free version of SPAMfighter for private users.
It has removed 701 spam emails to date.
Paying users do not have this message in their emails.
Try www.SPAMfighter.com for free now!
Message 18
| 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: Pretty darned confused about grounding shields |
--> AeroElectric-List message posted by: "Dan O'Brien" <danobrien@cox.net>
This is a keeper...........
Into my avionics folder goes this one.
A real keeper indeed --- pretty much just what the doctor ordered. Thanks
Vern and Wayne both for your help on this one.
--> AeroElectric-List message posted by: rv-9a-online
<<mailto:rv-9a-online@telus.net?subject=Re:%20Pretty%20darned%20confused%20about%20grounding%20shields&replyto=200501290155.j0T1tf824333@matronics.com>rv-9a-online@telus.net>
OK, lots of confusing facts.
The purpose of a shield is to prevent outside interference or,
conversely, to prevent the signal from radiating interference. You'd
think that grounding both ends would be OK, but then we have an
interesting effect:
It's possible when grounding both ends, for current to flow in the
shield and through the equipment grounds. This current is caused by the
ever-present difference in ground voltages within each of the equipment
due to internal loads and wire lengths, etc.
When this occurs, high frequency longitudinal currents may flow in the
shield. This makes a good antenna, radiating energy around it, and
especially into the wire it's supposed to shield. The best way to
prevent this current flow is to not connect one end. Most of the
benefit will be gained by only connecting one end, and it does not
matter which end.
There is a theoretical additional benefit by ground the 'transmitter'
end (if you can figure this out) rather than the 'receiver' end, simply
because any noise in the transmitter ground should also be superimposed
on the transmitter signal, thus minimizing the (presumably noisy)
metallic currents (currents from signal to shield). This may slightly
reduce radiated interference.
Some think that it's better to ground only the audio panel/intercom end
of audio signals because that represents the system 'quiet point'. This
makes sense. A true quiet ground shield won't be radiating anything,
whereas a high power comm might have some ground bounce.
So, rules of thumb:
1) Don't ground both ends of a shield.
2) If not specified, ground the transmitter end only (most signals other
than audio signals); except
3) For audio signals, ground the audio panel end only.
I can't comment on Garmin's confusing documentation, except that the
tech rep is probably right. The engineer (blush) that wrote the Garmin
documentation is probably related to the guy who made Garmin avionics
trays 6.3125" wide rather than the 6.25" the rest of the civilized world
standardized on.
Vern Little, RV-9A
Dan O'Brien wrote:
>--> AeroElectric-List message posted by: "Dan O'Brien"
<<mailto:danobrien@cox.net?subject=Re:%20Pretty%20darned%20confused%20about%20grounding%20shields&replyto=200501290155.j0T1tf824333@matronics.com>danobrien@cox.net>
>
>After Wayne Sweet suggested the Garmin manual was off regarding shielding,
>I called the company. Ready for this?
>
>1. Connecting a UPS SL30 Nav Com to a MD200-306 CDI indicator: UPS manual
>(before the Garmin merger) says ground shields at both ends. They are
>SPECIFIC. For example, they have footnotes that explicitly say to ground at
>both ends, while they also have footnotes saying to let float the Nav/Com
>end of the connection to the audio panel. Couldn't be more explicit.
>However, the Garmin tech rep says to ground the shields only at the Nav/Com
>end. He says "I don't know why the manual says that?"
>2. Connecting a GNS430 GPS/Nav/Com to a MD200-306 CDI indicator: Garmin
>manual says ground shields at both ends.
>However, the Garmin tech rep says to ground the shields only at the Nav/Com
>end. He says "I don't know why the manual says that?"
>3. Connecting a GNS430 to an altitude serializer: Garmin manual says ground
>the shield at both ends.
>However, the Garmin tech rep says to ground the shield only at the Garmin
end;
>while the Microencoder rep says ground the shield at the Microencoder end
>(the "sending" end).
>
>Almost as bad as economists (my field). OK scientists, there either IS a
>right answer to each question, or there are tradeoffs that are worth
>understanding. Inquiring (if somewhat mystified, and a little irritated)
>minds want to know.
Message 19
| 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: Open letter to the list |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
Sorry to drop a "bomb" and then run.
Well KOMPUTUR failed and backups not so good. Then internet connection
(Directway) failed. Still down, (for general info I live out where cable dsl
etc are not available so I have a satellite ground station where I uplink to
the satellite my outgoing and down link from the satellite the incomming.
With that mode NFG its its SLOW telecon modem and tonight only 300+ emails
to look at. New computer + new software etc etc.
It will be at least a week before back to normal at best. (Kant even smell
chk until more SW is loaded.)
Any way. I have test data, facts and lots of industry references on my side
(oops as we are not taking sides just offering more info to consider) as
well as a team of 6 others who have over 200 years experience 9with my time
added in its nearly 250 years of related experience). Not that we are right,
as that is not the point, just to point out alternatives and their merits.
This is not to say Bob is wrong, just there are more than one proper
solution and what is fine for one might not be even reasonable for another.
For example a C150 in day VFR in uncontrolled airspace is very different
than an auto engine conversion where it takes over 10+ amps to keep the prop
turning. The C150 flys with no battery or alternator while the auto
conversion needs lots of amps from somewhere ALL the time
Diferent solutions to different problems.
BUT in general I feel its time to leap into the modern age and use some real
rugged automotive components that are far more reliable and pass much more
rugged testing requirements than the infamous DO-160.
Also my testing has led to a series of problems etc etc that needed more
investigation. I have testing that is st least repeatable for me as well as
industry reports for backup. This has kept the report in a constant state of
flux. Add been sick and Wife is not at all well last yeasr and now there is
not a lot of time to work on things.
However I have not found any show stoppers than need immediate attention.
(Perhaps those in the middle of wiring would disagree.)
How about NO fuses, practically no CB's NO relays, simple controls etc
nearly all solid state with smarts built in. Eric would have no contactors
or fuses or CB's anywhere. Its possible today with off the shelf parts and
much lighter and potentially lower cost and far more reliable. End of final
soap box conclusion as that is were its all ending up.
Below Bob you left out option 4 in your list. Perhaps Paul (et al) are
right. :-), welllll he has a point in the design for a specific application
etc :-)
Anyway I will return when the dust settles (mine) with talking points one at
a time, perhaps one per week so things are not so confusing with many
discussions at once.
Paul
----- Original Message -----
From: Robert L. Nuckolls, III <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Open letter to the list
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<b.nuckolls@cox.net>
>
> Close but no cigar. I'll remind folks that the ultimate proof
> of any science is the repeatable experiment. George says he can
> blow transorbs in a heartbeat. We'll need details of his test
> environment before any query or argument can be mounted. Paul
> says he has come conclusions to make based on his testing. I presume
> he'll be willing to detail his experiments. If I have anything to
> contribute to the conversations, I'll have to either (1) show where
> the setup is wrong or (2) explain how the interpretation is in
> error or (3) go to the shop and repeat the experiment for closer
> examination.
>
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! --
|