Today's Message Index:
----------------------
1. 01:09 AM - Re: Re: Dual Fuel Pumps and EFI (John Burnaby)
2. 03:57 AM - Volts and Amps (Carlos Trigo)
3. 04:08 AM - Re: How to test the OV? (Stewart, Michael (ISS Atlanta))
4. 04:09 AM - Re: How to test the OV? (Stewart, Michael (ISS Atlanta))
5. 04:52 AM - Re: EI V/A Discharge light (PETER LAURENCE)
6. 06:12 AM - Re: Dual Fuel Pumps and EF (Gary Casey)
7. 06:21 AM - Re: Volts and Amps (Robert L. Nuckolls, III)
8. 06:44 AM - Re: EI V/A Discharge light (Robert L. Nuckolls, III)
9. 06:59 AM - Re: Volts and Amps (Ken)
10. 07:14 AM - Diagnostic Scope, Was: Re: OVP crowbar false triggering (BobsV35B@aol.com)
11. 07:17 AM - Re: Re: DC fans problem. (Robert L. Nuckolls, III)
12. 07:25 AM - Re: Volts and Amps (Robert L. Nuckolls, III)
13. 07:30 AM - Re: Diagnostic Scope, Was: Re: OVP crowbar false triggering (BobsV35B@aol.com)
14. 07:33 AM - Re: Diagnostic Scope (Robert L. Nuckolls, III)
15. 07:37 AM - Re: Loadmeter (Robert L. Nuckolls, III)
16. 08:22 AM - Re: How to test the OV? (Robert L. Nuckolls, III)
17. 09:03 AM - Re: Volts and Amps (Phil Birkelbach)
18. 09:54 AM - Re: EI V/A Discharge light (Robert L. Nuckolls, III)
19. 11:41 AM - Specs for FlightCom 403?? (Phil White)
20. 11:42 AM - Re: Re: Dual Fuel Pumps and EFI (Glaeser, Dennis A)
21. 12:20 PM - Re: Specs for FlightCom 403?? (Gerry Holland)
22. 01:43 PM - B&C conversation on operating SD8 (Bill Schlatterer)
23. 02:21 PM - Re: B&C conversation on operating SD8 (Hinde, Frank George (Corvallis))
24. 04:48 PM - Re: DC fans problem (Eric M. Jones)
25. 06:14 PM - Re: Specs for FlightCom 403?? (Charlie England)
26. 08:15 PM - Re: Re: DC fans problem (Robert L. Nuckolls, III)
27. 08:44 PM - Instrument Holes in DWF format (Emrath)
28. 09:06 PM - Old radio manual source (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Re: Dual Fuel Pumps and EFI |
--> AeroElectric-List message posted by: "John Burnaby" <jonlaury@impulse.net>
Thanks to all for your suggestions.
After reading them all, I realize the pedestrian idea of having one SPST per pump
is the simplest, least expensive, and least maintenance option. And I forget
who said it, but when the fire goes out and my "on" indicator light for pump
# 2 is lit, I'm still going to hit its manual over ride to "on".
Now, can anyone tell me how to respond to a thread on the list without having to
copy the Subject line and paste it into a new message? I couldn't find a "Post
reply" button and I tried clicking the Re: (subject) line with no joy.
Thanks,
John
Message 2
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Received-SPF: softfail (mta2: domain of transitioning trigo@mail.telepac.pt does
not designate 85.138.30.109 as permitted sender) receiver=mta2; client_ip=85.138.30.109;
envelope-from=trigo@mail.telepac.pt;
--> AeroElectric-List message posted by: "Carlos Trigo" <trigo@mail.telepac.pt>
I am bulding an all electric RV-9A with an electrically dependent Subaru engine.
It has 2 batteries and the Subaru internal regulated alternator, and will
be using the ExpBus.
I am intending to measure Volts and Amps where needed to always monitor, at land
(before leaving it) and in flight (to know if I have to land ASAP), if there
are enough electrons to keep me out of a gliding experience.
Regarding Amps, I am thinking to measure them in 3 places, the alternator output
and the 2 batteries, in order to know "who" is charging and discharging and
"how much" each. By an arithmetic sum, this will even give me the total current
being used by the plane.
Is this a good design? Where exactly should I hook the ammeter wires? Should I
use shunts or Hall effect sensors? And to work as I want, I suspect I will have
to put 3 separate indicators in my pannel, right?
Regarding Volts, I believe I should measure them in 2 places, which are the 2
batteries. Is this right? And again, where exactly should I hook the voltmeter
wires? And should I use 2 voltmeters or only one with a comuting switch?
At thousands of miles of phisical distance from you guys, this list has been my
DC electric university, therefore:
Answers and other comments from Bob and the usual suspects are most wellcome, even
required... :
)
Thanks
Carlos Trigo
Portugal
Message 3
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| Subject: | How to test the OV? |
--> AeroElectric-List message posted by: "Stewart, Michael (ISS Atlanta)" <mstewart@iss.net>
Hmmm. Variable power supply.... I don't have one of those.
I do have a 24v charger airvraft that would be a good substitute?
Mike
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Vincent Welch
Subject: RE: AeroElectric-List: How to test the OV?
--> AeroElectric-List message posted by: "Vincent Welch"
<welchvincent@hotmail.com>
Mike,
I tested mine with a variable power supply. I put the OVP is series
with a
current limiting resistor and the power supply. I put a voltmeter
across
the resitor and slowly increased the voltage until the SCR tripped and
the
voltage across the resistor jumped up. I believe that it tripped at
16.5
volts. This was tested on the bench before I ever installed in on the
plane.
Vince
>From: "Stewart, Michael (ISS Atlanta)" <mstewart@iss.net>
>Reply-To: aeroelectric-list@matronics.com
>To: <aeroelectric-list@matronics.com>
>Subject: AeroElectric-List: How to test the OV?
>Date: Fri, 15 Jul 2005 11:30:07 -0400
>
>--> AeroElectric-List message posted by: "Stewart, Michael (ISS
Atlanta)"
><mstewart@iss.net>
>
>How do I test my AEC OVP module? I have an internally regulated alt.
and
>the
>I have searched the archives. And cant find the answer. I have the
>pre-wired solenoid with the OV crowbar. S701-2
>http://www.bandc.biz/S701-2.html
>
>
>Thanks
>Mike
>Do not archive
>
>
Message 4
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| Subject: | How to test the OV? |
--> AeroElectric-List message posted by: "Stewart, Michael (ISS Atlanta)" <mstewart@iss.net>
In that thinking, I would have to disconnect the main buss from it so in
case it failed I would not be sending 24v through my 14v system?
Mike
Do not archive?
-----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: How to test the OV?
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<nuckollsr@cox.net>
At 03:15 PM 7/18/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: "Vincent Welch"
><welchvincent@hotmail.com>
>
>Mike,
>
>I tested mine with a variable power supply. I put the OVP is series
with a
>current limiting resistor and the power supply. I put a voltmeter
across
>the resitor and slowly increased the voltage until the SCR tripped and
the
>voltage across the resistor jumped up. I believe that it tripped at
16.5
>volts. This was tested on the bench before I ever installed in on the
>plane.
That's what it's supposed to do. Suggest you do this every
annual on ANY form of ov protection. I worked a case of smoked
electronics many moons ago where the ov relay failed to catch
a runaway alternator. A lead wire had broken off inside the
relay at some undertmined time in the past rendering the
ov protection inoperative.
Bob . . .
Message 5
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| Subject: | Re: EI V/A Discharge light |
--> AeroElectric-List message posted by: PETER LAURENCE <plaurence@the-beach.net>
Bob,
Tim at B&C told me that the LR3 trips at approx 12.5 to
12.7 V. The SB1A-14 trips at 13V.
Peter
>>Bob,
>>
>>Thanks for input. I will perform diagnostic test per
>>note 8 when I get
>>back to plane. But I'm somewhat baffled by why the "low
>>voltage warning
>>light" from the LR3C regulator doesn't come on if there
>>is zero output
>>from the alternator....I thought that was the purpose of
>>the "warning light"?
>
> Yes . . . but if there are very light loads on the
>battery, the battery
> might support the bus above the low voltage light
>trip point. Nominally
> they're set for 13.0 volts. Easy to check on the
>bench with a power
> supply and good meter. Further, do not assume that
>because all the
> various voltmeters are hooked to "the system" that
>they're all going
> to read the same voltage for a variety of reasons
>that include votlage
> drop in system conductors and instrument accuracy.
>
> The best check is to measure the trip points and
>calibration of each
> instrument independently before you start chasing
>down other variables
> in the system. The LR-3 trip point is set up by
>precision resistors and
> a precision reference device. It MIGHT be that one of
>the resistors is
> a wrong value but I would be skeptical . . . the 13.0
>plus or minus 0.2
> volt is an acceptance test parameter at B&C.
>
> Bob . . .
>
>
>page,
>
>
>
>
Message 6
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| Subject: | Re: Dual Fuel Pumps and EF |
--> AeroElectric-List message posted by: Gary Casey <glcasey@adelphia.net>
I basically agree with Bob, but the operative condition is that with
a manual system safety in the case of a pump failure to totally
dependent on the operator doing the right thing at the right time. I
have a system designed, not yet installed, that uses a pressure
switch and a relay wired to turn the pump on an hold it on in case of
a pressure loss. It is accompanied by a "pump on" warning. I expect
that a pump failure will result in no event except the light coming
on and that I propose is better than a silent engine followed by a
pilot trying to figure out what to do next. The extra complexity
will never result in the pump not coming on as there is a manual "on"
position as well. Also, I see no reason to install a "transducer" as
someone suggested because the exact value of the switchpoint isn't
important. (I assume he is referring to an analog pressure sensor,
the output of which would have to be measured by some electronics and
compared to a reference switchpoint voltage)
Gary Casey
>
> I want to wire 2 fuel pumps, for an EFI system, into AEC schematic
> Z-14 so
> that when fuel pressure drops below a preset psi, the secondary
> pump turns
> on and locks on ,and I want to have manual overides.
>
How does your engine behave under in-flight fuel starvation? Does it
present a situation that is difficult or dangerous to recover from?
The reason I ask is because systems with automatic features
generally
have parts counts several times that of a simple manual system. In
all of the airplanes I fly, fuel starvation due to a misplacement of
fuel selector valve or failure of primary pump will recover in
seconds
after corrective action on the part of the pilot with very little
loss
of altitude.
> I was told pressure switches are not that accurate re repeatability
> and
> that I would be better off with a pressure transducer. I'm not sure
> what a
> transducer is and how it would be integrated into a switch that would
> control the pumps, but I'm guessing that the pressure sensing device
> (transducer?) would be wired into some sort of locking relay.
>
I'll suggest a careful consideration of added value for installing
this kind of system. Automatic or "smart" systems can have a way
of lulling a pilot into ill-placed confidence or worse, complacency.
They certainly add to cost of ownership in that there's just that
much "stuff" to buy, install, maintain, and break.
Bob . . .
Message 7
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| Subject: | Re: Volts and Amps |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 11:51 AM 7/19/2005 +0100, you wrote:
>--> AeroElectric-List message posted by: "Carlos Trigo"
><trigo@mail.telepac.pt>
>
> I am bulding an all electric RV-9A with an electrically dependent
> Subaru engine. It has 2 batteries and the Subaru internal regulated
> alternator, and will be using the ExpBus.
> I am intending to measure Volts and Amps where needed to always
> monitor, at land (before leaving it) and in flight (to know if I have to
> land ASAP), if there are enough electrons to keep me out of a gliding
> experience.
> Regarding Amps, I am thinking to measure them in 3 places, the
> alternator output and the 2 batteries, in order to know "who" is charging
> and discharging and "how much" each. By an arithmetic sum, this will even
> give me the total current being used by the plane.
>Is this a good design? Where exactly should I hook the ammeter wires?
>Should I use shunts or Hall effect sensors? And to work as I want, I
>suspect I will have to put 3 separate indicators in my pannel, right?
> Regarding Volts, I believe I should measure them in 2 places, which are
> the 2 batteries. Is this right? And again, where exactly should I hook
> the voltmeter wires? And should I use 2 voltmeters or only one with a
> comuting switch?
Voltmeters and ammeters have minimal if any useful value for
flight operations. Your #1 concern as PILOT is: Are alternator(s)
supporting all of ship's loads and (2) are battery(ies) all on
line and being charged by the alternator?
The very best WARNING tools for telling a PILOT that one of these
conditions is not being met is the low voltage warning light.
In your case (1 alt/dual bat) a low voltage warning fed from each
of the two battery busses would be useful. If either battery contactor
was open, the battery on that circuit would fall below the trip
point on the low voltage warning.
If any one of those lights comes on, it's time to switch to a carefully
crafted, well maintained PLAN-B wherein you KNOW what endurance is
available to you for comfortable termination of flight.
As a MECHANIC, it may be useful to know voltages and currents in
lots of places about the airplane and it's doubtful that any combination
of panel mounted devices and selector switches is going to tell you
everything you need to know to chase a rat out of the woodpile. So,
if probability is high that you'll need to get out the multimeter
to troubleshoot the airplane, then the decision as to how many places
you choose to monitor with your panel mounted instruments becomes
a toss-up.
My suggestion is to MINIMIZE complexity, parts count, weight, and
cost of ownership of your airplane. A part that's NOT installed is
not a part that will need to be fixed later. A system that's not
installed is not going to be a distraction to you when you should
be concentrating on comfortable termination of flight.
If it were my airplane, install the AMPs function as an alternator
loadmeter and provide some means by which each battery can be
probed independently - preferably with ACTIVE warning devices.
Everything else has an increasingly poor return on investment.
Bob . . .
Message 8
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| Subject: | Re: EI V/A Discharge light |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 09:12 PM 7/18/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: "William" <wschertz@ispwest.com>
>
>In a test I did, when the freshly charged battery is connected to the LR-3,
>and only the battery solenoid was being drawn from the battery, it took a
>couple of minutes for the voltage to drop enough for the LV light to start
>flashing. If there is any load on the system, I expect that it would come on
>faster.
Correct. It's been some years since I messed with the LR-3 so I
checked the B&C website for data. The LR-3 installation instructions
at:
http://bandc.biz/LR3INSTRUCT.pdf
Says the low voltage light operating range is 12.5 to 13.0 volts. In
another place, the statement is made that the low voltage light should
be flashing by the time bus voltage drops to 12.5 volts.
I set my LVWarn modules at 13.0 plus or minus about 0.1 volts
which might make them come on a little earlier than the warning
in an LR-3 but under normal operating conditions the differences
are insignificant.
A fully charged RG battery will present an open circuit voltage
greater than 12.5 volts. Actually, it's almost 13.0 volts. So it's
not unreasonable to expect the LR-3 to delay a period of time after
the battery master is turned on before the light flashes.
Bob . . .
Message 9
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| Subject: | Re: Volts and Amps |
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
I understand - except that once the low voltage light comes on - will
one have the discipline to act? I think a lot of the folks on this list
would then want to see what the voltage is so that they believe the
light. There is a human tendancy to not believe one indication and think
that it must be the low voltage detector that has failed. In addition
I'd find it comforting to be able to confirm proper voltage before
takeoff with an electrically dependant engine as I have seen voltage
regulators drift out of spec and cook batteries. I've also seen it where
the airplane was able to be repaired on the ground with screwdriver,
pliers, AND that panel mounted voltmeter because nothing else was
available. So... rather than a loadmeter, I'd opt for a voltmeter
capable of reading both battery voltages in addition to the low voltage
warning devices ;) A load meter seems less useful to me and if I really
really wanted one I'd rather use a hall sensor to avoid additional
connections for a shunt. If there are no voltmeters then I see the value
in a loadmeter to confirm low alternator output.
Ken
Robert L. Nuckolls, III wrote:
>--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>
>At 11:51 AM 7/19/2005 +0100, you wrote:
>
>
>
>>--> AeroElectric-List message posted by: "Carlos Trigo"
>><trigo@mail.telepac.pt>
>>
>> I am bulding an all electric RV-9A with an electrically dependent
>>Subaru engine. It has 2 batteries and the Subaru internal regulated
>>alternator, and will be using the ExpBus.
>> I am intending to measure Volts and Amps where needed to always
>>monitor, at land (before leaving it) and in flight (to know if I have to
>>land ASAP), if there are enough electrons to keep me out of a gliding
>>experience.
>> Regarding Amps, I am thinking to measure them in 3 places, the
>>alternator output and the 2 batteries, in order to know "who" is charging
>>and discharging and "how much" each. By an arithmetic sum, this will even
>>give me the total current being used by the plane.
>>Is this a good design? Where exactly should I hook the ammeter wires?
>>Should I use shunts or Hall effect sensors? And to work as I want, I
>>suspect I will have to put 3 separate indicators in my pannel, right?
>> Regarding Volts, I believe I should measure them in 2 places, which are
>>the 2 batteries. Is this right? And again, where exactly should I hook
>>the voltmeter wires? And should I use 2 voltmeters or only one with a
>>comuting switch?
>>
>>
>
> Voltmeters and ammeters have minimal if any useful value for
> flight operations. Your #1 concern as PILOT is: Are alternator(s)
> supporting all of ship's loads and (2) are battery(ies) all on
> line and being charged by the alternator?
>
> The very best WARNING tools for telling a PILOT that one of these
> conditions is not being met is the low voltage warning light.
> In your case (1 alt/dual bat) a low voltage warning fed from each
> of the two battery busses would be useful. If either battery contactor
> was open, the battery on that circuit would fall below the trip
> point on the low voltage warning.
>
> If any one of those lights comes on, it's time to switch to a carefully
> crafted, well maintained PLAN-B wherein you KNOW what endurance is
> available to you for comfortable termination of flight.
>
> As a MECHANIC, it may be useful to know voltages and currents in
> lots of places about the airplane and it's doubtful that any combination
> of panel mounted devices and selector switches is going to tell you
> everything you need to know to chase a rat out of the woodpile. So,
> if probability is high that you'll need to get out the multimeter
> to troubleshoot the airplane, then the decision as to how many places
> you choose to monitor with your panel mounted instruments becomes
> a toss-up.
>
> My suggestion is to MINIMIZE complexity, parts count, weight, and
> cost of ownership of your airplane. A part that's NOT installed is
> not a part that will need to be fixed later. A system that's not
> installed is not going to be a distraction to you when you should
> be concentrating on comfortable termination of flight.
>
> If it were my airplane, install the AMPs function as an alternator
> loadmeter and provide some means by which each battery can be
> probed independently - preferably with ACTIVE warning devices.
> Everything else has an increasingly poor return on investment.
>
> Bob . . .
>
>
>
Message 10
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| Subject: | Re: OVP crowbar false triggering |
--> AeroElectric-List message posted by: BobsV35B@aol.com
Good Morning Bob,
I looked on their website and see that those units have been disconnected.
Do you have a recommendation for a replacement?
Happy Skies,
Old Bob
AKA
Bob Siegfried
Ancient Aviator
Stearman N3977A
Brookeridge Airpark LL22
Downers Grove, IL 60516
630 985-8502
In a message dated 7/19/2005 8:29:21 A.M. Central Standard Time,
nuckollsr@cox.net writes:
my all time favorite investigative tool is the Tektronix
TDS210/220 series digital 'scopes. They're small, light,
very fast and will dump a screen to a printer. I have
a portable battery/inverter pak that will support the
scope and an inkjet printer for use in the field.
Message 11
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| Subject: | Re: DC fans problem. |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 06:16 PM 7/18/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>
>--> AeroElectric-List message posted by: "John Swartout"
><jgswartout@earthlink.net>
>
> >Eric, would you recommend one of these Transient Voltage Suppressors
> >[Bidirectional transorb P6KE18CA] for
> >a Commercial Aviation Products 12VDC flap actuator (Model D145-00-36-3)?
> >John
>
>John,
>
>Yes, I would.... Although Bob N. objects to sprinking these things around,
>he comes from a large family of muggles who don't believe in wizardry at
>all..
Nope, I prefer confidence in my instruments and the repeatable
experiment. Haven't found a "glitch" with enough energy in it to
wake up a snoozing mosquito much less justify extra-ordinary
prophylaxis. (See my post on the DC fan "problem" of last week).
If one has concerns for the nano-transient, certainly a single
trap device at the bus would be sufficient. The best trap
is the ship's battery. Very narrow, fast rise time events
have a difficult time getting past a capacitor too.
I'm still waiting for details of a bench test that demonstrates
the value of adding one of these things ANYWHERE much less
all over the airplane. Thus far all I've noticed are quotations
from the manuals (produced by folks who sell Transorbs) that
highly recommend a multi-junction vaccination of every electrical
system. In light of those recommendations, I'm still marveling
at how we managed to get along without them for nearly 90 years
of sticking DC powered electro-whizzies in airplanes.
It's only recently that our systems have become sprinkled with
such devices . . . in the latest and greatest of composite
airplanes. Sadly, the threat is of our own design. We built a machine
from materials having 1000 times the resistance of aluminum and
found that the energy in a lightning strike will wake deaf dogs
from a mile away. I didn't find a use for Transorbs in over 20 years
of aviation systems design until DO-160 added a new section on
indirect lightning effects where the energies applied to my
electro-whizzy were on the order of 600v with a 2 ohm source
impedance (300 amps)!
Now, if anyone anticipates close encounters with strikes of the
worst kind, all bets are off . . . I don't care how many Transorbs
you sprinkle around the airplane if you haven't tested effectiveness
in the lab. But for everything else, show me the schematic, parts
list and measurements of the energies observed. I keep getting
assurances that the evils exist but to date, not a single repeatable
experiment to support the hypothesis.
Bob . . .
Message 12
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| Subject: | Re: Volts and Amps |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 10:01 AM 7/19/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
>I understand - except that once the low voltage light comes on - will
>one have the discipline to act? I think a lot of the folks on this list
>would then want to see what the voltage is so that they believe the
>light. There is a human tendancy to not believe one indication and think
>that it must be the low voltage detector that has failed.
Does one have the discipline to keep that nose DOWN and airspeed
UP even if it means landing short of the end of the runway? It's
damned
> In addition
>I'd find it comforting to be able to confirm proper voltage before
>takeoff with an electrically dependant engine as I have seen voltage
>regulators drift out of spec and cook batteries.
I'm not suggesting that one shouldn't consider leaving them
off the airplane. They have some utility (especially in
pre-flight BEFORE you become a pilot) but they poor in-flight
warning devices and possibly more distraction than assistance
when you KNOW that PLAN-B, PLAN-C . . . etc is the next sure
step to a happy end on the day.
> I've also seen it where
>the airplane was able to be repaired on the ground with screwdriver,
>pliers, AND that panel mounted voltmeter because nothing else was
>available. So... rather than a loadmeter, I'd opt for a voltmeter
>capable of reading both battery voltages in addition to the low voltage
>warning devices ;) A load meter seems less useful to me and if I really
>really wanted one I'd rather use a hall sensor to avoid additional
>connections for a shunt. If there are no voltmeters then I see the value
>in a loadmeter to confirm low alternator output.
Sounds like a plan . . .
Bob . . .
Message 13
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| Subject: | Re: OVP crowbar false triggering |
--> AeroElectric-List message posted by: BobsV35B@aol.com
In a message dated 7/19/2005 9:12:59 A.M. Central Standard Time, Bobs V35B
writes:
I looked on their website and see that those units have been disconnected.
Do you have a recommendation for a replacement?
Obviously, should have said discontinued rather than disconnected!
Happy Skies,
Old Bob
AKA
Bob Siegfried
Ancient Aviator
Stearman N3977A
Brookeridge Airpark LL22
Downers Grove, IL 60516
630 985-8502
Message 14
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| Subject: | Re: Diagnostic Scope |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 10:12 AM 7/19/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: BobsV35B@aol.com
>
>
>Good Morning Bob,
>
>I looked on their website and see that those units have been disconnected.
>Do you have a recommendation for a replacement?
There are 7 of the 210/220 series scopes on ebay right now.
Given the inherent robustness of Tektronix products, any
offering that's not covered in mud dobber nests and bird
poop is a low-risk buy. Try to find one with the printer
port adapter included (this will boost the price by $150
to $200).
There's a newer version available from the factory but
they'll cost you about 2x a used one . . . something
on the order of $1300.
Bob . . .
>In a message dated 7/19/2005 8:29:21 A.M. Central Standard Time,
>nuckollsr@cox.net writes:
>
>my all time favorite investigative tool is the Tektronix
>TDS210/220 series digital 'scopes. They're small, light,
>very fast and will dump a screen to a printer. I have
>a portable battery/inverter pak that will support the
>scope and an inkjet printer for use in the field.
Message 15
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 10:04 PM 7/18/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: plaurence@the-beach.net
>
>Bob N. ,
>
>Do you have a source for an Alternator loadmeter?
>
>I believe you once carried this product.
Yeah, I've got a box of 100 cores on my shop floor
right now waiting for the time to re-scale them
into http://www.aeroelectric.com/Pictures/Loadmeter_2.jpg
These are 10x the instrument that Westach builds.
Won't mind putting my brand on these movements by
Triplett.
I'm also working on a process where I MIGHT be able
to offer white lettering on a black face. No
promises for when but these will eventually find
their way onto my website.
Bob . . .
Message 16
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| Subject: | How to test the OV? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 07:06 AM 7/19/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: "Stewart, Michael (ISS Atlanta)"
><mstewart@iss.net>
>
>In that thinking, I would have to disconnect the main buss from it so in
>case it failed I would not be sending 24v through my 14v system?
>Mike
>Do not archive?
You need to take the device out of the airplane to test it.
Also, consider that a multimeter is your first electrical
test instrument of choice while a bench power supply is
the second. You can get really nice new ones like:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7530894056&category=58286&rd=1
I have more kinds and sizes of power supplies than
any other item of test equipment. Do an ebay
search on 30v power supply and you'll get a dozen
or more choices that are good values.
Bob . . .
Message 17
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| Subject: | Re: Volts and Amps |
--> AeroElectric-List message posted by: Phil Birkelbach <phil@petrasoft.net>
I wound up with three volt meters by accident. The Dynon D-10 measures
the voltage on the main power feed and the backup feed. This gives me
voltage on my main buss and my essential buss. The EIS-4000 engine
monitor also gives voltage on the wire that powers it up (in my case the
essential buss). Neither of these required me to do anything other than
wire them up to the same power that I would have done otherwise. The
EIS also has alarm setpoints that can be applied to the voltage. I also
have two home grown low voltage monitors installed so if my alternator
goes offline I would think it'd be hard to miss.
Godspeed,
Phil Birkelbach - Houston Texas
RV-7 N727WB - Finishing Up
http://www.myrv7.com
Ken wrote:
>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
>I understand - except that once the low voltage light comes on - will
>one have the discipline to act? I think a lot of the folks on this list
>would then want to see what the voltage is so that they believe the
>light. There is a human tendancy to not believe one indication and think
>that it must be the low voltage detector that has failed. In addition
>I'd find it comforting to be able to confirm proper voltage before
>takeoff with an electrically dependant engine as I have seen voltage
>regulators drift out of spec and cook batteries. I've also seen it where
>the airplane was able to be repaired on the ground with screwdriver,
>pliers, AND that panel mounted voltmeter because nothing else was
>available. So... rather than a loadmeter, I'd opt for a voltmeter
>capable of reading both battery voltages in addition to the low voltage
>warning devices ;) A load meter seems less useful to me and if I really
>really wanted one I'd rather use a hall sensor to avoid additional
>connections for a shunt. If there are no voltmeters then I see the value
>in a loadmeter to confirm low alternator output.
>
>Ken
>
>Robert L. Nuckolls, III wrote:
>
>
>
>>--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>>
>>At 11:51 AM 7/19/2005 +0100, you wrote:
>>
>>
>>
>>
>>
>>>--> AeroElectric-List message posted by: "Carlos Trigo"
>>><trigo@mail.telepac.pt>
>>>
>>> I am bulding an all electric RV-9A with an electrically dependent
>>>Subaru engine. It has 2 batteries and the Subaru internal regulated
>>>alternator, and will be using the ExpBus.
>>> I am intending to measure Volts and Amps where needed to always
>>>monitor, at land (before leaving it) and in flight (to know if I have to
>>>land ASAP), if there are enough electrons to keep me out of a gliding
>>>experience.
>>> Regarding Amps, I am thinking to measure them in 3 places, the
>>>alternator output and the 2 batteries, in order to know "who" is charging
>>>and discharging and "how much" each. By an arithmetic sum, this will even
>>>give me the total current being used by the plane.
>>>Is this a good design? Where exactly should I hook the ammeter wires?
>>>Should I use shunts or Hall effect sensors? And to work as I want, I
>>>suspect I will have to put 3 separate indicators in my pannel, right?
>>>Regarding Volts, I believe I should measure them in 2 places, which are
>>>the 2 batteries. Is this right? And again, where exactly should I hook
>>>the voltmeter wires? And should I use 2 voltmeters or only one with a
>>>comuting switch?
>>>
>>>
>>>
>>>
>> Voltmeters and ammeters have minimal if any useful value for
>> flight operations. Your #1 concern as PILOT is: Are alternator(s)
>> supporting all of ship's loads and (2) are battery(ies) all on
>> line and being charged by the alternator?
>>
>> The very best WARNING tools for telling a PILOT that one of these
>> conditions is not being met is the low voltage warning light.
>> In your case (1 alt/dual bat) a low voltage warning fed from each
>> of the two battery busses would be useful. If either battery contactor
>> was open, the battery on that circuit would fall below the trip
>> point on the low voltage warning.
>>
>> If any one of those lights comes on, it's time to switch to a carefully
>> crafted, well maintained PLAN-B wherein you KNOW what endurance is
>> available to you for comfortable termination of flight.
>>
>> As a MECHANIC, it may be useful to know voltages and currents in
>> lots of places about the airplane and it's doubtful that any combination
>> of panel mounted devices and selector switches is going to tell you
>> everything you need to know to chase a rat out of the woodpile. So,
>> if probability is high that you'll need to get out the multimeter
>> to troubleshoot the airplane, then the decision as to how many places
>> you choose to monitor with your panel mounted instruments becomes
>> a toss-up.
>>
>> My suggestion is to MINIMIZE complexity, parts count, weight, and
>> cost of ownership of your airplane. A part that's NOT installed is
>> not a part that will need to be fixed later. A system that's not
>> installed is not going to be a distraction to you when you should
>> be concentrating on comfortable termination of flight.
>>
>> If it were my airplane, install the AMPs function as an alternator
>> loadmeter and provide some means by which each battery can be
>> probed independently - preferably with ACTIVE warning devices.
>> Everything else has an increasingly poor return on investment.
>>
>> Bob . . .
>>
>>
>>
>>
>>
>
>
>
>
Message 18
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| Subject: | Re: EI V/A Discharge light |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 07:48 AM 7/19/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: PETER LAURENCE
><plaurence@the-beach.net>
>
>Bob,
>
>Tim at B&C told me that the LR3 trips at approx 12.5 to
>12.7 V. The SB1A-14 trips at 13V.
>
>Peter
That tracks with the data from their information sheets.
It's been a long time ago and I don't recall now what
thinking preceded the decisions on set-points but either
is fine.
Bob . . .
Message 19
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| Subject: | Specs for FlightCom 403?? |
--> AeroElectric-List message posted by: "Phil White" <philwhite9@aol.com>
Anybody know about the audio quality of the FlightCom 403??
I emailed FlightCom asking for audio specs on the 403 stereo intercom,
and received the following reply:
>"I am sorry we do not have these specs
>Bruce"
Makes me think they don't much want to sell their products to builders!!
Subject: Tech specs for Flightcom 403
Can you provide Frequency responce (w/deviation in db), signal to noise
ratio? I have downloaded the manual, but it doesn't include this
information.
Message 20
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| Subject: | Re: Re: Dual Fuel Pumps and EFI |
--> AeroElectric-List message posted by: "Glaeser, Dennis A" <dennis.glaeser@eds.com>
>Now, can anyone tell me how to respond to a thread on the list
without having to
>copy the Subject line and paste it into a new message? I
couldn't find a "Post
>reply" button and I tried clicking the Re: (subject) line with
no joy.
>
>Thanks,
>John
I think the only way to do that is if you have the list messages or
digest sent to your email account :-( If you get individual messages
sent, you can reply easily, but if you get the digest, then you have to
delete all the stuff you don't want (or else the message gets really
long really fast).
If you use the web interface (like I do so my email inbox doesn't get
filled up) we're stuck with the cut/paste scenario.
Dennis Glaeser
Message 21
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| Subject: | Re: Specs for FlightCom 403?? |
--> AeroElectric-List message posted by: Gerry Holland <gholland@gemini-resourcing.com>
Phil
> Anybody know about the audio quality of the FlightCom 403??
I regularly fly in a 2 seat Homebuilt with the Flightcom 403 as part of
Avionics install. It works well and quality sounds good.
With respect regarding the following statement...
> Makes me think they don't much want to sell their products to builders!!
Why do you say that? Their product seems OK to me and I've heard no bad
reports. Regarding the following point:
> Can you provide Frequency responce (w/deviation in db), signal to noise
> ratio?
Is it out of interest you ask, or is it part of a selection criteria?
It would have been agreeable if the information had been given but it's
certainly not mission critical data. The cockpit environment of any Aircraft
is hostile at most times relating to noise and I'm not sure that knowing the
information you asked is that relevant. Squelch selection will effect any
audio performance and will be based on the operating cycle the aircraft is
being flown.
It certainly doesn't merit an opinion that this Company is not interested.
Said in a spirit of politeness!
Regards
Gerry
Message 22
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| Subject: | B&C conversation on operating SD8 |
--> AeroElectric-List message posted by: "Bill Schlatterer" <billschlatterer@sbcglobal.net>
Just thought SD8 owners might be interesting in what Tim at B&C had to say
about the SD8 operating procedures. Might want to read bottom up.
Bill S
7a Ark fuse panel
-----Original Message-----
From: Tim Hedding [mailto:tim@bandc.info]
Subject: RE: B&C reply
Bill,
Either procedure will work but the procedure you describe is the most
efficient use of available energy. In this case load management decisions
are made in advance by the builder, not left up to the pilot and the
particular flight conditions. Careful choosing of the items on the E-bus is
important. Otherwise there may be something over on the primary bus you want
to get to.
Having both alternators on shouldn't hurt any thing. One can't "back-feed"
the other. Though I haven't tested this particular scenario, I suspect the
alternators will not load share proportionally because of different overall
gain on the alternator/regulator pairs. Depending on regulator set-points
and gains it might be possible for the SD8 to be fully loaded continuously
while the L40 is lightly loaded.
Also, because of the nature of the regulators, you may find the bus noisier
with the SD8 ON. It uses a switched full-wave bridge rectifier that
generates more noise than the L40.
The SD8 uses two sealed ball bearings. Being spline driven, there are
insignificant radial bearing loads regardless of output. Net torque required
at zero output should be only enough to overcome friction. Even though the
rotor "cogs" around because of the magnets, the energy applied to climb the
magnetic force at each pole should be equal to the energy returned going off
the backside of the pole.
As output goes up, driving torque will go up. Horsepower required will be 1
Horsepower for each 746 watts x efficiency. If the SD8 is 65% efficient,
full output will be had for around 1/4 Horsepower.
Masking of primary alternator failure as you describe is possible during
periods of low bus loads.
Hope I haven't confused you more.
Tim
-----Original Message-----
From: Bill Schlatterer [mailto:billschlatterer@sbcglobal.net]
Subject: RE: B&C reply
Tim, thanks for the reply but it doesn't quite add up to me yet. According
to Bob, first response to a LV/OV warning would be to 1) shut down the main
alternator, 2) endurance bus on, 3) master to off to kill whatever is on on
the primary buss and immediately drop to the endurance buss load to extend
the battery life. 4) Now SD8 on, hopefully with less than 8 amps draw on
the endurance bus. The diode is already pointed at the E-bus which is
without power, not because of a diode failure but because you have killed
the master bat switch. In this case, a diode failure would be the same as
turning the master off.
Again, this is using Z13 with your 40amp and LRC13, so there is an always
hot bus then a E-bus switch to the E-bus with the diode between the e-bus
and the primary/main. SD8 goes to the battery side/always hot side of the
starter switch so it will charge the battery and run the always hot and
E-buss with the master off..... I think?
Couple of points to confirm:
If everything is running fine and I just turn on the SD8, nothing should
happen except that I get the normal 40A off the main alternator plus 8-10
from the SD8! True?
Being gear driven, the SD8 is always spinning anyway so is there any
additional wear/load to keep it running?
I understand that the reason not to leave it running is that it would mask a
primary alternator failure. Sounds true?
Thanks for your help, the subject is a little confusing to me at this point.
Bill S
-----Original Message-----
From: Tim Hedding [mailto:tim@bandc.info]
Subject: B&C reply
Bill,
The standby alternator is normally OFF in this system. The warning lamp can
be left out, or better, wire it through a second pole on the standby
alternator master switch so that if the standby alternator is selected OFF,
the lamp won't stay lit. The light will still come ON if the standby
alternator is selected ON and the breaker trips. The installation
instructions were written with the idea in mind that the SD8 is the only
charging system in the airplane such as in Day/VFR aerobatic airplanes.
Normally, the Alternate E-bus Feed switch is OFF, even if the standby
alternator is ON. The Alternate E-bus Feed is turned on if the E-bus feed
diode opens and leaves the E-bus without power.
Make sense?
Tim Hedding
Message 23
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| Subject: | B&C conversation on operating SD8 |
--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
Interesting,
Here is what I am thinking of doing.
Use the engine monitor to measure the current from the main alternator
(SD8 will normally be off). Set an alarm at below the normal day VFR
loads (all electric airplane this will be roughly 5 amps). Use the
normal OV warning light from the main alt as a digital input to the
engine monitor. Both of these alarms will be annunciated thru the
headset.
With this annunciation, shut down the field supply to the main alt and
the kilovolt contactor...Thus main alt is completely out of circuit.
Switch on SD8 which will be wired directly to the endurance bus.
Those are plans so far.
Frank
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Bill
Schlatterer
Subject: AeroElectric-List: B&C conversation on operating SD8
--> AeroElectric-List message posted by: "Bill Schlatterer"
--> <billschlatterer@sbcglobal.net>
Just thought SD8 owners might be interesting in what Tim at B&C had to
say about the SD8 operating procedures. Might want to read bottom up.
Bill S
7a Ark fuse panel
-----Original Message-----
From: Tim Hedding [mailto:tim@bandc.info]
Subject: RE: B&C reply
Bill,
Either procedure will work but the procedure you describe is the most
efficient use of available energy. In this case load management
decisions are made in advance by the builder, not left up to the pilot
and the particular flight conditions. Careful choosing of the items on
the E-bus is important. Otherwise there may be something over on the
primary bus you want to get to.
Having both alternators on shouldn't hurt any thing. One can't
"back-feed"
the other. Though I haven't tested this particular scenario, I suspect
the alternators will not load share proportionally because of different
overall gain on the alternator/regulator pairs. Depending on regulator
set-points and gains it might be possible for the SD8 to be fully loaded
continuously while the L40 is lightly loaded.
Also, because of the nature of the regulators, you may find the bus
noisier with the SD8 ON. It uses a switched full-wave bridge rectifier
that generates more noise than the L40.
The SD8 uses two sealed ball bearings. Being spline driven, there are
insignificant radial bearing loads regardless of output. Net torque
required at zero output should be only enough to overcome friction. Even
though the rotor "cogs" around because of the magnets, the energy
applied to climb the magnetic force at each pole should be equal to the
energy returned going off the backside of the pole.
As output goes up, driving torque will go up. Horsepower required will
be 1 Horsepower for each 746 watts x efficiency. If the SD8 is 65%
efficient, full output will be had for around 1/4 Horsepower.
Masking of primary alternator failure as you describe is possible during
periods of low bus loads.
Hope I haven't confused you more.
Tim
-----Original Message-----
From: Bill Schlatterer [mailto:billschlatterer@sbcglobal.net]
Subject: RE: B&C reply
Tim, thanks for the reply but it doesn't quite add up to me yet.
According to Bob, first response to a LV/OV warning would be to 1) shut
down the main alternator, 2) endurance bus on, 3) master to off to kill
whatever is on on the primary buss and immediately drop to the endurance
buss load to extend the battery life. 4) Now SD8 on, hopefully with
less than 8 amps draw on the endurance bus. The diode is already
pointed at the E-bus which is without power, not because of a diode
failure but because you have killed the master bat switch. In this
case, a diode failure would be the same as turning the master off.
Again, this is using Z13 with your 40amp and LRC13, so there is an
always hot bus then a E-bus switch to the E-bus with the diode between
the e-bus and the primary/main. SD8 goes to the battery side/always hot
side of the starter switch so it will charge the battery and run the
always hot and E-buss with the master off..... I think?
Couple of points to confirm:
If everything is running fine and I just turn on the SD8, nothing should
happen except that I get the normal 40A off the main alternator plus
8-10 from the SD8! True?
Being gear driven, the SD8 is always spinning anyway so is there any
additional wear/load to keep it running?
I understand that the reason not to leave it running is that it would
mask a primary alternator failure. Sounds true?
Thanks for your help, the subject is a little confusing to me at this
point.
Bill S
-----Original Message-----
From: Tim Hedding [mailto:tim@bandc.info]
Subject: B&C reply
Bill,
The standby alternator is normally OFF in this system. The warning lamp
can be left out, or better, wire it through a second pole on the standby
alternator master switch so that if the standby alternator is selected
OFF, the lamp won't stay lit. The light will still come ON if the
standby alternator is selected ON and the breaker trips. The
installation instructions were written with the idea in mind that the
SD8 is the only charging system in the airplane such as in Day/VFR
aerobatic airplanes.
Normally, the Alternate E-bus Feed switch is OFF, even if the standby
alternator is ON. The Alternate E-bus Feed is turned on if the E-bus
feed diode opens and leaves the E-bus without power.
Make sense?
Tim Hedding
Message 24
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| Subject: | Re: DC fans problem |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<nuckollsr@cox.net>
>>--> AeroElectric-List message posted by: "Eric M. Jones"
>><emjones@charter.net>
>>
>>--> AeroElectric-List message posted by: "John Swartout"
>><jgswartout@earthlink.net>
>>
> >Eric, would you recommend one of these Transient Voltage Suppressors
> >[Bidirectional transorb P6KE18CA] for
> >a Commercial Aviation Products 12VDC flap actuator (Model D145-00-36-3)?
> >John
>
>John,
>
>>Yes, I would.... Although Bob N. objects to sprinking these things around,
>he comes from a large family of muggles who don't believe in wizardry at
>all..
>Nope, I prefer confidence in my instruments and the repeatable
>experiment. Haven't found a "glitch" with enough energy in it to
>wake up a snoozing mosquito much less justify extra-ordinary
>prophylaxis. (See my post on the DC fan "problem" of last week).
>If one has concerns for the nano-transient, certainly a single
>trap device at the bus would be sufficient. The best trap
>is the ship's battery. Very narrow, fast rise time events
>have a difficult time getting past a capacitor too.
The best way to stop transient is "at the source". This is far more
efficient, since the farther a transient goes, the less you know about it
AND the more it radiates--even if it gets weaker.
>I'm still waiting for details of a bench test that demonstrates
>the value of adding one of these things ANYWHERE much less
>all over the airplane. Thus far all I've noticed are quotations
>from the manuals (produced by folks who sell Transorbs) that
>highly recommend a multi-junction vaccination of every electrical
>system. In light of those recommendations, I'm still marveling
>at how we managed to get along without them for nearly 90 years
>of sticking DC powered electro-whizzies in airplanes.
Well, 90 years ago (when we were just "a Hershey bar in daddy's back
pocket"), There were no integrated circuits, 2-volt microprocessors,
untra-sensitive this or that and all that square wave data that Fouriers its
way into an infinity of frequencies. The issue of EMC developed because of
the huge increase in the use of electronics, and their importance to the
user. When I began developing electronic (medical) devices, this was not
really an issue. I'm sure it was the same in the avionics biz.
> It's only recently that our systems have become sprinkled with
>such devices . . . in the latest and greatest of composite
>airplanes. Sadly, the threat is of our own design. We built a machine
>from materials having 1000 times the resistance of aluminum and
>found that the energy in a lightning strike will wake deaf dogs
>from a mile away. I didn't find a use for Transorbs in over 20 years
>of aviation systems design until DO-160 added a new section on
>indirect lightning effects where the energies applied to my
>electro-whizzy were on the order of 600v with a 2 ohm source
>impedance (300 amps)!
>Now, if anyone anticipates close encounters with strikes of the
>worst kind, all bets are off . . . I don't care how many Transorbs
>you sprinkle around the airplane if you haven't tested effectiveness
>in the lab. But for everything else, show me the schematic, parts
>list and measurements of the energies observed. I keep getting
>assurances that the evils exist but to date, not a single repeatable
>experiment to support the hypothesis....Bob . . .
Testing the effectiveness in a properly equipped lab is visciously
expensive. So we fall to "Best Practices". One can always claim that "...not
a single repeatable experiment to support the hypothesis...." Madman Muntz
would wander his TV development labs with wire cutters and remove parts.
Often the TV would just keep working. If the TV quit working he would tell
the engineer to solder it back in. I could certainly remove 50% of the
rivets in my airplane and it would fly just as well--at least for a while.
It is easy to show that a transient gets generated, but very difficult or
impossible to show it has a particular effect. But the subtle performance of
everything around it degrades in ways that are hard to quantify. So I say
just put the transorb in. The least that will happen is that the
survivability of the electrical system will improve a little.
The MAC 8A trim box has no capacitors across the motor brushes nor from
brush to ground. I added the caps but "...not a single repeatable experiment
to support the hypothesis...." was found. I didn't look at the system before
or after the modification with an oscilloscope or a spectrum analyzer.
Reasonable men can disagree on this, but my experience is that using "Best
Practices" avoids having to deal with unforseen and unpredictable issues
downstream. After completing a project, troubleshooting can be much simpler
if all the little details have been handled along the way.
(By the way...I'm still dissolving the epoxy from the Powerlink Jr. More
later).
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
(508) 764-2072
What the West really has to offer is honesty. Somehow, in the midst of their
horrid history, the best among the Gaijin learned a wonderful lesson. They
learned to distrust themselves, to doubt even what they were taught to
believe
or what their egos make them yearn to see. To know that even truth must be
scrutinized, it was a great discovery....
-- David Brin, "Dr. Pak's Preschool"
Message 25
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| Subject: | Re: Specs for FlightCom 403?? |
--> AeroElectric-List message posted by: Charlie England <ceengland@bellsouth.net>
It's unfortunate they weren't interested in supplying the requested
info. Having said that, it's a virtual certainty that signal to noise
will be far better than needed in an a/c and unless they intentionally
did something to limit freq response, it will exceed your needs as well.
Off-the-shelf electronic parts are so good these days you have to try to
make specs worse than needed. It is possible that they might
intentionally limit freq response to the speech range to make
communications clearer, but they should be willing to tell you if that's
the case. With a stereo intercom limiting the freq response would
obviously be counter-productive.
Charlie
Phil White wrote:
>--> AeroElectric-List message posted by: "Phil White" <philwhite9@aol.com>
>
>Anybody know about the audio quality of the FlightCom 403??
>
>I emailed FlightCom asking for audio specs on the 403 stereo intercom,
>and received the following reply:
>
> >"I am sorry we do not have these specs
>
> >Bruce"
>
>Makes me think they don't much want to sell their products to builders!!
>
>To: service@flightcom.net
>Subject: Tech specs for Flightcom 403
>Can you provide Frequency responce (w/deviation in db), signal to noise
>ratio? I have downloaded the manual, but it doesn't include this
>information.
>
Message 26
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| Subject: | Re: DC fans problem |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>The best way to stop transient is "at the source". This is far more
>efficient, since the farther a transient goes, the less you know about it
>AND the more it radiates--even if it gets weaker.
Very true . . . but assuming also that the transient is worthy
of consideration. The one I saw on the "problem" fan was
trivial to the extreme.
> >I'm still waiting for details of a bench test that demonstrates
> >the value of adding one of these things ANYWHERE much less
> >all over the airplane. Thus far all I've noticed are quotations
> >from the manuals (produced by folks who sell Transorbs) that
> >highly recommend a multi-junction vaccination of every electrical
> >system. In light of those recommendations, I'm still marveling
> >at how we managed to get along without them for nearly 90 years
> >of sticking DC powered electro-whizzies in airplanes.
>
>Well, 90 years ago (when we were just "a Hershey bar in daddy's back
>pocket"), There were no integrated circuits, 2-volt microprocessors,
>untra-sensitive this or that and all that square wave data that Fouriers its
>way into an infinity of frequencies. The issue of EMC developed because of
>the huge increase in the use of electronics, and their importance to the
>user. When I began developing electronic (medical) devices, this was not
>really an issue. I'm sure it was the same in the avionics biz.
Correct . . . but from day-one every silicon circuit destined to
reside in an airplane was built to design rules suggested
by DO160/MS704. We ASSUMED robust transients and designed
the system to to stand them off. A relatively trivial task.
I've been tying silicon to busses for years and have never
felt the slightest inclination to tell users of my products that
they might want to sprinkle some added protection around
the airplane . . . had I done so, my boss would no doubt
have heard about it in short order!
I've tied all manner of silicon to the raw bus on all
manner of airplane with nary a concern for telling a pilot
or systems integrator that he should "pamper" my product
in any way.
> >It's only recently that our systems have become sprinkled with
> >such devices . . . in the latest and greatest of composite
> >airplanes. Sadly, the threat is of our own design. We built a machine
> >from materials having 1000 times the resistance of aluminum and
> >found that the energy in a lightning strike will wake deaf dogs
> >from a mile away. I didn't find a use for Transorbs in over 20 years
> >of aviation systems design until DO-160 added a new section on
> >indirect lightning effects where the energies applied to my
> >electro-whizzy were on the order of 600v with a 2 ohm source
> >impedance (300 amps)!
>
> >Now, if anyone anticipates close encounters with strikes of the
> >worst kind, all bets are off . . . I don't care how many Transorbs
> >you sprinkle around the airplane if you haven't tested effectiveness
> >in the lab. But for everything else, show me the schematic, parts
> >list and measurements of the energies observed. I keep getting
> >assurances that the evils exist but to date, not a single repeatable
> >experiment to support the hypothesis....Bob . . .
>
>Testing the effectiveness in a properly equipped lab is visciously
>expensive.
I wasn't suggesting that any OBAM aircraft builder embark on
a program to lightning proof his project. But there's no good
reason not to understand and deal logically with everything
less than lightning strikes. Transient energies for events
generated on board are small and easily managed.
>So we fall to "Best Practices". One can always claim that "...not
>a single repeatable experiment to support the hypothesis...." Madman Muntz
>would wander his TV development labs with wire cutters and remove parts.
>Often the TV would just keep working. If the TV quit working he would tell
>the engineer to solder it back in. I could certainly remove 50% of the
>rivets in my airplane and it would fly just as well--at least for a while.
Poor analogy. Madman Muntz wouldn't get to first base
on Lord Kelvin's ball field. "Best Practice" can be a
euphemism for "I don't really understand what's going on
here". Many folk working in and for the FAA operate with
the "Best Practice" rulebooks under their arms. Nobody
working for me would be allowed to sprinkle anything into
our products under the banner of "Best Practice".
"When you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind: it may be the
beginning of knowledge, but you have scarcely, in your
thoughts, advanced to the stage of science." -LK
I would amplify that sentiment with the notion that it
doesn't rise to the level of engineering either.
>It is easy to show that a transient gets generated, but very difficult or
>impossible to show it has a particular effect.
So we make some unidentified, un-quantified allegations
and then act on the strength of the allegations? I could
expand the "Best Practice" mantra and suggest that shielding
every wire in the airplane breaks a potential coupling mode
for "noises" without ever having identified or quantified
the noise.
99.9% of the time the DO160/MS704 protocols have served us
well and they're not difficult to implement. I can't even
recall an EMC/Noise issue that turned out to be anything other
than a failure to accomplish due diligence under DO160/MS704.
There's trash on a biz-jet bus 1000x worse than the little
spike that comes out of that fan.
> But the subtle performance . . .
. . . "subtle" is a non-quantified, non-engineering term . . .
>
>of everything around it degrades in ways that are hard to quantify. So I say
>just put the transorb in. The least that will happen is that the
>survivability of the electrical system will improve a little.
>
>The MAC 8A trim box has no capacitors across the motor brushes nor from
>brush to ground. I added the caps but "...not a single repeatable experiment
>to support the hypothesis...." was found. I didn't look at the system before
>or after the modification with an oscilloscope or a spectrum analyzer.
>
>Reasonable men can disagree on this, but my experience is that using "Best
>Practices" avoids having to deal with unforseen and unpredictable issues
>downstream. After completing a project, troubleshooting can be much simpler
>if all the little details have been handled along the way.
Putting caps on the brushes of PM motors is a well founded
practice measured and validated countless times. At the same
time, thousands of MAC actuators are flying with operators
reporting no problems. But we can pump up the "Best Practice"
mantra here too . . . how about offering common mode chokes
AND capacitors and recommend them for ALL motors? Those would
do just as much as a Transorb for clipping the nanospike
on the itty-bitty fan while running some additional insignificant
noises to ground as well. Shucks, let's put the transorbs in
too. I think I saw a drawing where the author recommended THREE
transorbs per motor! This could be the beginnings of a really
good motor filter business. See:
http://www.aeroelectric.com/Pictures/super_duper_filter.pdf
All we have to do is propagate the right kinds of allegations
and worries to folks who believe they are looking to us for
good advice. Where does one draw the line? I prefer to offer
solutions to real identifiable and quantified issues and
leave "Best Practice" marketing to others.
Bob . . .
Message 27
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| Subject: | Instrument Holes in DWF format |
--> AeroElectric-List message posted by: "Emrath" <emrath@comcast.net>
I recall a recent posting requesting a CAD drawing of an instrument hole. If
anyone has a "symbol" for a standard 3.125 and 2.5" hole cut out, I'd sure
would like it. I'm trying to layout my panel and ensure it all fits.
Appreciate having this if someone has already done this. My version of Turbo
Cad will read DWF files as will AutoCAD. Thanks in advance.
Do not Archive
Marty in Brentwood TN
Message 28
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| Subject: | Old radio manual source |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
See:
http://www.avionix.com/manuals.html
Bob . . .
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