Today's Message Index:
----------------------
1. 12:43 AM - Re: Bob, thermistors for low fuel warning WARNING (Scott, Ian)
2. 05:06 AM - Re: Bob, thermistors for low fuel warning WARNING (Trampas)
3. 06:37 AM - Re:AOL Blocking All Email From Matronics.Com (KahnSG@aol.com)
4. 07:28 AM - Re: Bob, thermistors for low fuel warning (Robert L. Nuckolls, III)
5. 07:47 AM - Re: Romulin disrupter (Robert L. Nuckolls, III)
6. 07:54 AM - Re: AWG (Robert L. Nuckolls, III)
7. 08:49 AM - Re: Re:AOL Blocking All Email From Matronics.Com (BobsV35B@aol.com)
8. 09:23 AM - Re: Battery Contactor vibration problem (Robert L. Nuckolls, III)
9. 09:30 AM - Re: Alternator Terminals ... (Robert L. Nuckolls, III)
10. 11:17 AM - Dimmers (Geoff Evans)
11. 11:45 AM - Current Limiters (PTACKABURY@aol.com)
12. 12:14 PM - Re: Crimping dies (Ron Raby)
13. 12:38 PM - Z-13 Question (Charles Brame)
14. 02:02 PM - Re: Crimping dies (Dawson, Bill)
15. 02:19 PM - Re: Battery Contactor vibration problem (Robert L. Nuckolls, III)
16. 02:25 PM - Re: Z-13 Question (Robert L. Nuckolls, III)
17. 03:49 PM - Re: Current Limiters (Robert L. Nuckolls, III)
18. 03:49 PM - Re: Dimmers (Robert L. Nuckolls, III)
19. 03:57 PM - Re: Bob, external power receptacle (J. Oberst)
20. 05:14 PM - Re: Dimmers (Robinson, Chad)
21. 06:51 PM - Re: Crimping dies (Charlie & Tupper England)
22. 06:58 PM - Re: Dimmers (Jim Daniels)
23. 07:53 PM - Encoder / Transponder domino failure? (SportAV8R@aol.com)
24. 08:33 PM - Re: Re: Battery Contactor vibration problem (Vince Ackerman)
25. 09:08 PM - Small aux battery: diode vs. relay (Geoff Evans)
26. 10:09 PM - Neutral cure silicone and urethane adhesive (Rob W M Shipley)
27. 10:43 PM - Source for BNC adapters? (HCRV6@aol.com)
28. 11:00 PM - Re: Re: Dimmers ()
Message 1
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| Subject: | Bob, thermistors for low fuel warning WARNING |
"ax" <aeroelectric-list@matronics.com.Gecko/20030624.Netscape/7.1>
--> AeroElectric-List message posted by: "Scott, Ian" <ian_scott@rslcom.com.au>
is this wise to run a device that deliberately heats up inside your fuel tank?
what are the explosive risks if it where to fail?
Ian
----------------------------------------------------
RSL COM has an extensive and competitive range of
local and long distance call packages. We also
offer converged multimedia and data services through
our own state-of-the-art integrated voice & data network.
Visit http://www.rslcom.com.au to find out more.
This message is for the named person's use only.
Privileged/confidential information may be contained in
this message. If you are not the addressee indicated in
this message (or responsible for delivery of the message
to such person), you may not copy or deliver this
message to anyone. In such case, you should destroy
this message, and notify us immediately.
Any views expressed in this message are those of the
individual sender, except where the message states
otherwise and the sender is authorised to state them to
be the views of any such entity.
----------------------------------------------------
Message 2
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| Subject: | Bob, thermistors for low fuel warning WARNING |
--> AeroElectric-List message posted by: "Trampas" <tstern@nc.rr.com>
I have worked on many cars and seen fuel pumps with black marks on the fuel
pump from electrical arcing, and yes these were in tank fuel pumps. The
reason that the tanks do not explode is that you have to have oxygen, fuel,
and heat for a fire.
Actually a friend of mine was a fireman, he said that car gas tanks were
more dangerous when empty than when full because when empty you had more
oxygen in the tank. He said this increased the likely hood of the tank
exploding, of course he also said in all the car fires he had been to never
once did he see an explosion.
The heat generated by the thermistors would be much lower than heat
generated by a fuel pump in normal operation. Also if you think about it,
the resistive float senders have current running through them and thus they
also will heat up as well.
To look at it another way, there are millions of cars on the road with these
types of low fuel warnings, I know I personally have never heard of one of
them exploding.
However as Bob says, you need to "fly comfortable" if you feel this is a
risk then it is your plane and you have to don't have to put one in.
Trampas
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Scott,
Ian
Subject: RE: AeroElectric-List: Bob, thermistors for low fuel warning
WARNING
--> AeroElectric-List message posted by: "Scott, Ian"
<ian_scott@rslcom.com.au>
is this wise to run a device that deliberately heats up inside your fuel
tank? what are the explosive risks if it where to fail?
Ian
----------------------------------------------------
RSL COM has an extensive and competitive range of
local and long distance call packages. We also
offer converged multimedia and data services through
our own state-of-the-art integrated voice & data network.
Visit http://www.rslcom.com.au to find out more.
This message is for the named person's use only.
Privileged/confidential information may be contained in
this message. If you are not the addressee indicated in
this message (or responsible for delivery of the message
to such person), you may not copy or deliver this
message to anyone. In such case, you should destroy
this message, and notify us immediately.
Any views expressed in this message are those of the
individual sender, except where the message states
otherwise and the sender is authorised to state them to
be the views of any such entity.
----------------------------------------------------
Message 3
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| Subject: | Re:AOL Blocking All Email From Matronics.Com |
--> AeroElectric-List message posted by: KahnSG@aol.com
Matt:
The direct no. for the AOL postmaster is : 1-888-212-5537
Steve
Message 4
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| Subject: | Bob, thermistors for low fuel warning |
WARNING
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
WARNING
At 08:06 AM 10/20/2003 -0400, you wrote:
>--> AeroElectric-List message posted by: "Trampas" <tstern@nc.rr.com>
>
>I have worked on many cars and seen fuel pumps with black marks on the fuel
>pump from electrical arcing, and yes these were in tank fuel pumps. The
>reason that the tanks do not explode is that you have to have oxygen, fuel,
>and heat for a fire.
>
>Actually a friend of mine was a fireman, he said that car gas tanks were
>more dangerous when empty than when full because when empty you had more
>oxygen in the tank. He said this increased the likely hood of the tank
>exploding, of course he also said in all the car fires he had been to never
>once did he see an explosion.
This simple law of physics has killed more than one welder . . .
>The heat generated by the thermistors would be much lower than heat
>generated by a fuel pump in normal operation. Also if you think about it,
>the resistive float senders have current running through them and thus they
>also will heat up as well.
It isn't so much a matter of total energy or heat as it is concentration
of energy. The energy in watt-seconds delivered by a spark plug is
measured in thousands of a watt-second . . . or millijoules. Your
strobes give you a nice bright light with 20 JOULES of energy per flash,
your sparkplug has to light the fire with 1,000th that level of energy.
It does it by concentrating release of energy in a very small space
that under ideal conditions is shared with a stoichiometric combination
of fuel and oxidizer.
>To look at it another way, there are millions of cars on the road with these
>types of low fuel warnings, I know I personally have never heard of one of
>them exploding.
>
>However as Bob says, you need to "fly comfortable" if you feel this is a
>risk then it is your plane and you have to don't have to put one in.
This is correct. There are several ways to make an electrical system
peacefully co-exist with a potentially explosive environment. One is
to seal the ignition source so completely that explosive constituents
can't get to it (use around oil refineries). Another is to enclose
the ignition source in a container stout enough to withstand an
internal explosion and/or vent the enclosure to the outside through
flame arresting vents (very common in motors). Yet another way is
to design for intrinsically safe energy levels carried by potential
ignition sources within the hazardous atmosphere. The last philosophy
says that no matter how the electrical device fails, it cannot deliver
sufficient energy even to a stoichiometric mixture to get
ignition. This technique has been used successfully for hundreds of
millions of automobiles and other gasoline driven machines for nearly
100 years.
Another aspect of explosion science is that for the explosion to
occur with maximum release of energy, you need to achieve stoichiometric
or ideal proportions of fuel and oxidizer . . . like setting your
mixture control for max rpm on the engine. Effectiveness of combustion
falls off rapidly on either side of the ideal ratio.
A tank with ANY amount of liquid fuel at the bottom will have an
atmosphere above the fuel that is SATURATED . . . i.e. contains
as many dissolved molecules of fuel as the space can contain at
the present temperature and pressure. This ratio of fuel to
oxidizer is a long way from stoichiometric. Every aviation
fuel tank SHOULD have unusable fuel . . . a low space were water
and fuel will collect in a manner that is inaccessible to the
engine but accessible to a sump drain.
This is one of the simple-ideas that argues against the popularly
circulated story about TWA800 . . . Jet A is specifically designed
for it's airplane friendly characteristics. Just as fuel gages have
been used in cars for a century, a half century experience with
millions of flights have produced no examples of violation of
a this simple law of physics.
Now, if someone wants to talk about a LEAK into an enclose space
nearby but outside a tank . . . that is a whole new ball game. But
people who understand and use simple-ideas do not concern themselves
with fuel tank explosions. Now, if your airplane's fuel system is
capable of delivering every ounce of fuel to the engine, you might
want to rethink the design for a number of very good reasons.
Bob . . .
Message 5
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| Subject: | Re: Romulin disrupter |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 10:07 PM 10/19/2003 -0400, you wrote:
>--> AeroElectric-List message posted by: plaurence@the-beach.net
>
>Bob
>
>I'm helping a friend wire a Velocity XL RG. The Panel was done at a very
>well known
>avionics shop.
>
>There are twelve relays that switch position lights, strobes, pitot heat,
>bat master
>start , electronic ignition, etc. The switch panel for these items are
>overhead. The
>logic for these relays was that running "high" currents through wires (
>position lights?)
>extending from the fuselage to the overhead switch panel, would create
>some type of
>electrical interference , Magnetic fields, or the like and possibly
>disrupt panel
>avionics.
>Opinion?
You're the second builder in the past week to note the
acres-of-relays technique to achieve some ill-conceived benefit
in designing an aircraft electrical system.
See http://www.aeroelectric.com/Pictures/TooManyRelays.jpg
There is no foundation in physics or even demonstrated practice
for taking this blanket approach to potential interference
control. Further, it illustrates a serious lack of understanding
on the part of the designer. Worse yet, it increases weight,
complexity, cost of ownership and reduces reliability.
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
Message 6
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 10:16 AM 10/20/2003 +1000, you wrote:
>--> AeroElectric-List message posted by: "Scott, Ian"
><ian_scott@rslcom.com.au>
>
>
>HI Bob,
>
>Received the copy of the connection, and the Audio ISO board, thanks.
>
>As We do not have the same suppliers in Australia, I am wondering if you
>have a generic parts list for the parts in the Audio Amp.
>
>thanks
The description column is the generic data for
parts substitution. Any electronics supplier should
be able to provide ELECTRICALLY equivalent parts. There
is a small risk that some substituted parts wont fit the
holes in the board but this is a small risk.
Digikey will ship to Australia. I suspect duties
on a handfull of detail electronics parts is minimal
of not zero. Unless you have a local over-the-counter
electronics parts supplier that will help you stuff
all the holes with suitable parts, and internet order
to Digikey is still your best bet.
See http://www.digikey.com
Bob . . .
Message 7
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| Subject: | Re:AOL Blocking All Email From Matronics.Com |
--> AeroElectric-List message posted by: BobsV35B@aol.com
Hi Howard,
This was on the Matronics list
The direct no. for the AOL postmaster is : 1-888-212-5537
Happy Skies,
Old Bob
Message 8
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| Subject: | Re: Battery Contactor vibration problem |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 08:49 PM 10/19/2003 -0700, you wrote:
>--> AeroElectric-List message posted by: Vince Ackerman <vack@mac.com>
>
>Hey Bob,
>
>Got the B&C Contactor you generously sent me, and installed it today (
>thanks again, you da man). Did my "tap" test and it seems to work
>perfectly. I did take someone on the lists advice and mount it
>horizontally, but it works great and never disconnected no matter how
>much I tapped on the bracket it's mounted to. That gives me a little
>piece of mind.
>
>Did you have a chance to look at the one I sent you?
It was waiting for me in the mailbox when I got home
last night. I got the harness drawing for a Rotorway Exec 162
also.
I am mystified as to the rational for some of the architecture
decisions in this system. The most striking feature is the
fact that dual FADECs share common wiring, particularly connectors.
The system also has a lot of always hot wiring (no battery contactor)
which could not get approved on a certified airplane. It appears
that many of the decisions driving architecture had more to do
with the fabrication of harnesses for installation convenience and
little or no attention to failure mode effects analysis.
When you have dual systems intended to back each other up
in case of damage and/or component failure, you try to isolate
the two systems to the maximum extend possible including
separate/independent power sources.
I would not be comfortable owning this airplane with the
notion of using it to spend many hours aloft.
I'll try to investigate the battery contactor later today.
Bob . . .
Message 9
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| Subject: | Re: Alternator Terminals ... |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:32 PM 10/19/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: Jim Sower <canarder@frontiernet.net>
>
> Question for all you EEs out there. I'm putting a new alternator on my
>Velocity. This one will be internally regulated (and have the appropriate
>"crowbar" OV protection. The unit I am installing has two terminals
>arranged in a "T". One is "field" and the other is "Indicator" (idiot
>light). I am blessed that the builder didn't have a 20- or 22- ga wire to
>string from the "Alt" (split Alt-Master) switch, so he used both conductors
>of 2-wire shielded 24 ga for the 12 ft run from the switch to the
>regulator. Anyway, I am betting that one will be enough to excite the
>regulator and I can use the other for an idiot light.
Ignore the built in idiot light. There are failure modes that
this light will not annunicate. A separate, active notification
of low voltage like that offered in B&C Altenrator System Controllers
or at:
http://www.aeroelectric.com/Catalog/AEC/9005/9005.html
or
http://www.aeroelectric.com/articles/lvwarn/LVWarn-ABMM.html
and
http://www.aeroelectric.com/articles/lvwarn/9021-620.pdf
>Thing is, I have to determine which is which and how the "I" lead works (is
>it hot or grounded when there is no output). I aim to wire things up with
>jumpers and spin the alternator by hand, so to get the charging voltage at
>B+ I will need a resistor between B+ and the line back to the battery.
Not sure what you're suggesting here. If you want to test the alternator,
hook B+ to a battery through a reasonably robust fuse . . . sized for
alternator output if you're going to spin in hard enough to get full
output.
> That
>done, I can connect stuff up and see if, when all ready to go, the "I" lead
>is hot or grounded, and if it goes cold or breaks ground connection when I
>spin up the unit.
It's a pull down to ground. Hook a light bulb from bus to the "I" terminal.
>My questions are: Will this work (will I be able to easily twirl the pulley
>and get charging voltage if I put the proper resistor in the circuit (so it
>doesn't have to generate much current in order to build up charging
>voltage)? What would be an appropriate resistance (and size) of the
>resistor I am placing in the circuit?
If this is a new alternator, then it's a reasonable assumption that
it works. I'd ignore the "I" lead - UNLESS it's an OLD alternator
design that needs start-up excitation fed to this pin. In this case,
a 30-50 ohm, 2-watt resistor connected from B+ to "I" will do the
job.
Bob .. .
Message 10
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--> AeroElectric-List message posted by: Geoff Evans <hellothaimassage@yahoo.com>
Can anyone compare and contrast the panel lighting dimmer listed in Vans
catalog with the dimmer offered by B&C?
Both appear to good for 1.5A, but the Vans dimmer is less than half the cost
of the B&C dimmer. I know you get what you pay for, but I'd like to know what
the differences are. There is no picture in the Vans catalog, so I'm not
really too sure what they're offering.
Thanks.
-Geoff
RV-8 QB
__________________________________
Message 11
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| Subject: | Current Limiters |
--> AeroElectric-List message posted by: PTACKABURY@aol.com
Bob: I am resending this question as I never heard from you and maybe I was
a casuality of your server's battle with AOL. In any case, here goes:
Bob: Help!! I am building a Lancair IV and am at the wire stringing stage.
I have two 17 amp hour batteries and one 70 amp alternator. I have adopted a
version of your Z-13 for the power distribution architecture, but can't
figure out how many, where and what size current limiters I should use. Part of
the problem is I can't read the diagrams in your book as the small print is
fuzzy (and my eyes are on their sixth decade). Another problem is I don't know
how to size the current limiters: eg: one 40 amp at each battery and one 60
amp at the alternator, or are they sized based on wire size and length like
fuses and cbs. So please tell me how to configure my current limiters. thanks
and regards, paul
Message 12
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| Subject: | Re: Crimping dies |
--> AeroElectric-List message posted by: "Ron Raby" <ronr@advanceddesign.com>
Eric
I use the T&B TBM-8S. Not that cheap.
Ron Raby
----- Original Message -----
From: "Eric M. Jones" <emjones@charter.net>
Subject: AeroElectric-List: Crimping dies
> --> AeroElectric-List message posted by: "Eric M. Jones"
<emjones@charter.net>
>
> In preparation for the "CCA FatCables", I am searching for good crimping
> dies for AWG 1/0 to AWG 8 or so. Does anyone have a suggestion for good
> quality crimpers for these sizes for not too much money?
>
> Regards,
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge MA 01550-2705
> Phone (508) 764-2072
> Email: emjones@charter.net
>
> Heaven: A place where the French are the cooks,
> the Germans are the engineers,
> and the British are the policemen.
>
> Hell: A place where the British are the
> cooks, the French are the engineers,
> and the Germans are the policemen.
> --unknown
>
>
Message 13
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--> AeroElectric-List message posted by: Charles Brame <charleyb@earthlink.net>
Bob et.al.,
A couple (or three) dumb questions, thus showing my complete ingnorance
of things electrical.
I am wiring an SD-8 into my All Electric on a Budget RV-6A. Figure Z-13
shows 12AWG wire from the SD-8 to the S704-1 contactor, and from there
to the main battery contactor via a 16AWG fuselink. A 14AWG wire is
shown connecting the main battery contactor to the battery bus with
16AWG continuing on to the Ess bus. Z-13 also shows the SD-8 and
regulator leads to be 12AWG; however, the pigtails provided with my SD-8
are labeled 14AWG and the pigtails on the Regulator appear to be the
same or smaller.
Can I safely substitute 14AWG for the 12AWG? The run will be less than 3
feet and the wire must pass through a VM-1000 Hall Sensor (along with a
6AWG fat wire) thus the need for the smallest practical wire. If I can
use 14AWG wire, what should be the size of the fuselink?
To further muddy the situation, my E-bus is rather heavy with IFR
avionics and electric gyros - I estimate 20+ Amps with everything on.
And in a fit of overkill, my main contactor to Battery Bus is a robust 8AWG.
I sure appreaciate this forum and your outstanding advice.
Charlie Brame
RV-6A N11CB
San Antonio
Message 14
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--> AeroElectric-List message posted by: "Dawson, Bill" <Bill.Dawson@pepperdine.edu>
I use one from http://www.epm-avcorp.com/
It's been great.
Bill
-----Original Message-----
From: Ron Raby [mailto:ronr@advanceddesign.com]
Subject: Re: AeroElectric-List: Crimping dies
--> AeroElectric-List message posted by: "Ron Raby"
<ronr@advanceddesign.com>
Eric
I use the T&B TBM-8S. Not that cheap.
Ron Raby
----- Original Message -----
From: "Eric M. Jones" <emjones@charter.net>
Subject: AeroElectric-List: Crimping dies
> --> AeroElectric-List message posted by: "Eric M. Jones"
<emjones@charter.net>
>
> In preparation for the "CCA FatCables", I am searching for good crimping
> dies for AWG 1/0 to AWG 8 or so. Does anyone have a suggestion for good
> quality crimpers for these sizes for not too much money?
>
> Regards,
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge MA 01550-2705
> Phone (508) 764-2072
> Email: emjones@charter.net
>
> Heaven: A place where the French are the cooks,
> the Germans are the engineers,
> and the British are the policemen.
>
> Hell: A place where the British are the
> cooks, the French are the engineers,
> and the Germans are the policemen.
> --unknown
>
>
Message 15
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| Subject: | Re: Battery Contactor vibration problem |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 08:49 PM 10/19/2003 -0700, you wrote:
>--> AeroElectric-List message posted by: Vince Ackerman <vack@mac.com>
>
>Hey Bob,
>
>Got the B&C Contactor you generously sent me, and installed it today (
>thanks again, you da man). Did my "tap" test and it seems to work
>perfectly. I did take someone on the lists advice and mount it
>horizontally, but it works great and never disconnected no matter how
>much I tapped on the bracket it's mounted to. That gives me a little
>piece of mind.
>
>Did you have a chance to look at the one I sent you?
Yes. Went to the workbench and wired up your Cole-Hersee
contactor to a power supply and load resistor. Powered
it up at 10V and 15V. Lightly tapped with a
hammer and took the following response graphs:
http://www.aeroelectric.com/temp/CH10V.jpg
http://www.aeroelectric.com/temp/CH15V.jpg
Dug out a RBM/Stancor part and repeated the experiment:
http://www.aeroelectric.com/temp/RS15V.jpg
http://www.aeroelectric.com/temp/RS10V.jpg
Both brands of contactor are similarly affected
by the hammer taps.
After some reflection, I'm not surprised. While
relatively light taps were used, a rigid metal
mass striking another rigid metal mass can easily
generate acceleration pulses (shock)
of 100-1000G . . . The pulses are very short
meaning that the energy transferred is low . . .
but instantaneous force to components mounted
within can be substantial.
Forgive the non-quantified words above like "light"
"short" "substantial" and "low" . . . I don't have
the tools in my shop to instrument and quantify
these phenomenon. However, I will invoke some hands-
on experience with qualifying flight hardware at
shock levels of 400G or more . . . it's NOT difficult
to impart stimulus of 100 to 1000G in these situations.
You'll note that documented disruptions are on the order
of 1 to 3 milliseconds in length and steep sided.
The steep sides says there was no arc forming in the
contact gaps. You will also note that each event
generated 2 to 5 circuit interruptions (contact bounce).
Playing with the test fixture demonstrated that the
number of interruptions per event had more to do with
tapping-technique and chance than with any observable
difference between the two brands of contactor.
Okay, what's this all mean?
(1) let us note that both contactor designs are
at least 50 years old and no doubt been produced in
millions of parts. If the parts are still in production,
it's a fair assumption that the vast majority of
users have experienced satisfactory service life
WHETHER OR NOT they were aware of the propensity for
bouncing contacts if tapped with a hammer.
(2) the stimulus is not cyclical vibration but short,
high-g shocks . . . a stimulus rarely found in an
airframe or any other vehicle.
(3) Interruptions of 3 millisecond interruptions and
more are EXACTLY the kinds of power input perturbations
that DO-160 tells us to EXPECT and be prepared to
shrug it off.
(4) the act of rotating the mounting axis of a contactor
to ward off evil shocking spirits is not useful
. . . aerodynamic linear g-loads can be reasonably
expected to maximize through the vertical axis . . .
mechanical shock may come from any direction.
Bottom line:
If you hammer-tap any contactor of this genre, you'll
undoubtedly produce the same kind of interruptions
that Vince noted and brought to our attention. I'm
pleased to have an opportunity to compare two
brands of similar devices and to have a reason to sit
down and consider their relative design features.
It's useful to make a new discovery of old data and
understand its significance in the design and operation
of our airplanes.
What I've learned today doesn't change my recommendations
for using these el-cheapo contactors in a well-considered,
failure-tolerant design. I continue to be of the opinion
that they will give good value performance free of extraordinary
risk when mounted in any orientation for ease of installation.
>Thanks again
>
>Vince
Thank you sir! I figure any day you go to bed knowing
something you didn't know yesterday is a good day. This
would not have come to light without your observations
and a willingness to ask the question.
I cranked though a number of plausible but way-out-in-left-
field scenarios to explain what you observed. It was quite
useful to put all those hypotheses in the trash and
discover the truth . . . and best yet . . . to find that
it didn't matter!
Bob . . .
Message 16
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| Subject: | Re: Z-13 Question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 02:36 PM 10/20/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: Charles Brame
><charleyb@earthlink.net>
>
>Bob et.al.,
>
>A couple (or three) dumb questions, thus showing my complete ingnorance
>of things electrical.
>
>I am wiring an SD-8 into my All Electric on a Budget RV-6A. Figure Z-13
>shows 12AWG wire from the SD-8 to the S704-1 contactor, and from there
>to the main battery contactor via a 16AWG fuselink. A 14AWG wire is
>shown connecting the main battery contactor to the battery bus with
>16AWG continuing on to the Ess bus. Z-13 also shows the SD-8 and
>regulator leads to be 12AWG; however, the pigtails provided with my SD-8
>are labeled 14AWG and the pigtails on the Regulator appear to be the
>same or smaller.
Depending on where your battery is located, it may be useful
to make some of the runs 12AWG . . . An RV-8 with battery in
tail would be a good case in point. If your battery is up front,
14AWG with 18AWG fusible link is fine.
>Can I safely substitute 14AWG for the 12AWG? The run will be less than 3
>feet and the wire must pass through a VM-1000 Hall Sensor (along with a
>6AWG fat wire) thus the need for the smallest practical wire. If I can
>use 14AWG wire, what should be the size of the fuselink?
>
>To further muddy the situation, my E-bus is rather heavy with IFR
>avionics and electric gyros - I estimate 20+ Amps with everything on.
>And in a fit of overkill, my main contactor to Battery Bus is a robust 8AWG.
How much of this stuff do you need to run in the en route mode
of flight? This is suppose to be an endurance bus which (when
combined with unlimited engine driven support of 8-10A) saves
100% of battery reserves for the descent to landing phase.
Except for pitot heat, the SD-8 ought to very nicely carry
everything you need to use up fuel aboard and still have
lots of battery snort left to wrap up the flight running
anything NEEDED to get you on the ground. Suggest you revisit
your e-bus load analysis.
Bob . . .
Message 17
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| Subject: | Re: Current Limiters |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 02:44 PM 10/20/2003 -0400, you wrote:
>--> AeroElectric-List message posted by: PTACKABURY@aol.com
>
>Bob: I am resending this question as I never heard from you and maybe I was
>a casuality of your server's battle with AOL. In any case, here goes:
>
>Bob: Help!! I am building a Lancair IV and am at the wire stringing stage.
>I have two 17 amp hour batteries and one 70 amp alternator. I have adopted a
>version of your Z-13 for the power distribution architecture, but can't
>figure out how many, where and what size current limiters I should use.
> Part of
>the problem is I can't read the diagrams in your book as the small print is
>fuzzy (and my eyes are on their sixth decade).
I presume you're really looking at Z-14 . . . much more appropriate
to your class of aircraft and the alternators you've cited. If you'd
like to tape two pieces of paper together for a larger version of Z-14,
download
http://www.aeroelectric.com/articles/Appendix_Z_Drawings/z14h_A.pdf
and
http://www.aeroelectric.com/articles/Appendix_Z_Drawings/z14h_B.pdf
and with some minor scissors work and a little tape, you can have
an 11x15" drawing.
> Another problem is I don't know
>how to size the current limiters: eg: one 40 amp at each battery and one 60
>amp at the alternator, or are they sized based on wire size and length like
>fuses and cbs. So please tell me how to configure my current
>limiters. thanks
>and regards, paul
You need only two. An ANL60 (upper right corner of drawing) would be
just fine
for the 70A alternator, an ANL30 (lower left corner of drawing) would be
good
for the 40A alternator.
Bob . . .
Message 18
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 11:17 AM 10/20/2003 -0700, you wrote:
>--> AeroElectric-List message posted by: Geoff Evans
><hellothaimassage@yahoo.com>
>
>Can anyone compare and contrast the panel lighting dimmer listed in Vans
>catalog with the dimmer offered by B&C?
>
>Both appear to good for 1.5A, but the Vans dimmer is less than half the cost
>of the B&C dimmer. I know you get what you pay for, but I'd like to know what
>the differences are. There is no picture in the Vans catalog, so I'm not
>really too sure what they're offering.
I am unfamiliar with Van's offering. Can anyone help Geoff out here?
Bob . . .
Message 19
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| Subject: | Re: Bob, external power receptacle |
--> AeroElectric-List message posted by: "J. Oberst" <joberst@cox-internet.com>
Bob, I put your ground power circuit (without the indicator) into my
Glasair. One morning, I came into my hangar and found the airplane battery
dead.
The problem was that if you charge your battery, and then unplug the charger
without pulling out the controlling circuit breaker, the charging contactor
stays energized (and therefore drawing current) even with the master battery
switch off. This is an easy mistake to make.
Jim Oberst.
----- Original Message -----
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Bob, external power receptacle
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
>
> At 06:56 PM 10/17/2003 -0500, you wrote:
> >--> AeroElectric-List message posted by: Jerzy Krasinski
> ><krasinski@direcway.com>
> >
> >Bob,
> >I got a receptacle which is used commonly for connection to an external
> >battery if internal battery is week. I was told that the receptacle is
> >from a Cessna. I hoped for an easy installation but there are three
> >prongs there. Two big ones are described "+" (the central one), and
> >"-" (the side one). Unfortunately, there is a third one, smaller. No
> >description there, but there are two ~1A diodes connected to it, able
> >to conduct "from" the prong.
>
> There are two commonly used ground power receptacles in the
> wild. One is a Cole-Hersey product designed for over the road
> trucks and adapted to aircraft by Piper about 40 years ago.
> It's has be popularized as the "Piper style ground power jack."
> This is a simple, cylinder with outside shell as ground, and
> a single robust center pin as power.
>
> In the years BP (before Piper) the military and air transport
> communities developed a three terminal plug/socket combination
> which you have described. It's a military standard part used
> on many ground and air vehicle applications and is the connector
> of choice for most aircraft.
>
>
> >I would like to make the receptacle compatible with battery carts at
> >airports, so Cessna standard seems to be the right one. But how is the
> >third prong connected? Is it used to drive a relay or something?
>
> Consider what happens if you make or break a high current
> connection while energized. There is bound to be arcing that
> ultimately damages the contacts of the connector. The third
> pin is smaller (is sized only for mechanical robustness and
> carries only a few amps in operation) and shorter (connects
> AFTER the big guys are hooked up and disconnects BEFORE
> the big guys do). This pin is used to control a ground power
> contactor in the in a manner that makes sure that
> power cannot flow through the big pins while the connector
> is being mated or de-mated. Originally, this was the ONLY
> purpose for the small pin.
>
> Other features have been added over the years to include
> some components for ov and reverse polarity protection.
> I have illustrated wiring for both the Piper style and
> military style ground power jacks in an article at:
>
> http://www.aeroelectric.com/articles/grndpwr.pdf
>
> If it were my airplane, I'd go the "Piper" route.
> The military style is a pain in the arse to install.
> You need to fabricate your own door or mount it
> someplace where a door is not needed. The Piper
> style comes with its own door built in, is much
> easier to install, and probably lighter than
> the 3-pin connector installation.
>
> Another advantage of the Cole-Hersey connector
> is that you can have your own ground power jumper
> cables made up and it two is lighter than one
> using the fatter military style connector and
> a LOT less expensive.
>
> Bob . . .
>
>
> >I could not find anything on thet topic. I would appreciate your answer.
> >Thank you,
> >Jerzy
> >
> >Werner Schneider wrote:
> >
> > >--> AeroElectric-List message posted by: "Werner Schneider"
> > <wernerschneider@compuserve.com>
> > >
> > >Interesting approach, would wonder what happens if you have a fuel
injected
> > >engine with a return line (of "hot" fuel) back into the tanks.
> > >
> > >I'm using a optical device in my Glastar, works great and as it is LED
it
> > >needs nearly no power!!
> > >
> > >http://www.ppavionics.com/LFL.htm
> > >
> > >Werner
> > >
> > >----- Original Message -----
> > >
> > >
> > >
> > >>When the thermistor is immersed in fuel, the fuel keeps the thermistor
> > >>cooled off, the resistance remains high and the indicator light bulb
does
> > >>not light up.
> > >>
> > >>
> > >
> > >
> > >
> > >
> >
> >
>
> Bob . . .
>
> --------------------------------------------
> ( Knowing about a thing is different than )
> ( understanding it. One can know a lot )
> ( and still understand nothing. )
> ( C.F. Kettering )
> --------------------------------------------
>
>
Message 20
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--> AeroElectric-List message posted by: "Robinson, Chad" <crobinson@rfgonline.com>
In case nobody else responds, you can make some guesses if you squint hard at the
fourth-to-last picture here:
http://www.rvproject.com/20030505.html
Looks like a pot controlling a single, heat-sunk TO-220 package device with only
a few other components on the board. I'm guessing an LM317?
B&C's site has a picture of their dimmer, which doesn't look like much more, but
it's a heck of a big heat sink. Also, it includes some DB-9 connectors that
add to the parts count but makes it easier to hook up, and the mounting tabs look
a lot easier to work with. Bob, do you know where they sourced this heat sink?
Looks like a nice getup.
I see B&C also offers a 5A option, which will control a heck of a lot more lights
- no way will that itty bitty heat sink picture on this Van's builder's site
stand up to even a portion of that without torching the board, unless this picture
isn't of the right thing.
The TO-3 picture in even the smaller of B&C's site can better dissipate heat to
begin with (over the TO-220 package), so I'm certain it will stand up to the
load it says it will. But that setup I see pictured on this Van's builder's site
won't take more than 500mA or so unless there's a fan blowing on it - that
will limit the number of lights it can control. (Read as 1/3 as many lights, if
that. And don't plan on touching it.)
Bear in mind that linear regulators, which these all are, just convert the excess
voltage to heat, so the DIMMER your lights are the HOTTER they get (some people
find this counter-intuitive). That means that if you hardly dim your lights
you may never notice the difference, until you turn them way down one day and
the dimmer torches anything that might be touching it.
> -----Original Message-----
> From: Robert L. Nuckolls, III [mailto:bob.nuckolls@cox.net]
> Sent: Monday, October 20, 2003 6:49 PM
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Dimmers
>
>
> --> AeroElectric-List message posted by: "Robert L. Nuckolls,
> III" <bob.nuckolls@cox.net>
>
> At 11:17 AM 10/20/2003 -0700, you wrote:
> >--> AeroElectric-List message posted by: Geoff Evans
> ><hellothaimassage@yahoo.com>
> >
> >Can anyone compare and contrast the panel lighting dimmer
> listed in Vans
> >catalog with the dimmer offered by B&C?
> >
> >Both appear to good for 1.5A, but the Vans dimmer is less
> than half the cost
> >of the B&C dimmer. I know you get what you pay for, but I'd
> like to know what
> >the differences are. There is no picture in the Vans
> catalog, so I'm not
> >really too sure what they're offering.
>
> I am unfamiliar with Van's offering. Can anyone help Geoff out here?
>
> Bob . . .
>
>
> ============
> ============
Message 21
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| Subject: | Re: Crimping dies |
--> AeroElectric-List message posted by: Charlie & Tupper England <cengland@netdoor.com>
Eric M. Jones wrote:
>--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>
>In preparation for the "CCA FatCables", I am searching for good crimping
>dies for AWG 1/0 to AWG 8 or so. Does anyone have a suggestion for good
>quality crimpers for these sizes for not too much money?
>
>Regards,
>Eric M. Jones
>www.PerihelionDesign.com
>113 Brentwood Drive
>Southbridge MA 01550-2705
>Phone (508) 764-2072
>Email: emjones@charter.net
>
The best crimper you can buy for 'not too much money' for big wires is
a propane torch.
Charlie
(Let the 'stress riser games' begin...)
:-)
Message 22
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--> AeroElectric-List message posted by: Jim Daniels <jwdanie@comcast.net>
At the top of this page is a picture of the Vans dimmer boards.
http://home.comcast.net/~jwdanie/Wiring2/wiring2.html
They just use an LM317 with a remote pot and another divider resistor.
The 317 has a minimal heatsink (I'm only drawing ~350ma so not a
problem). Note that the board contains locations for filter capacitors
but they are not populated. I opted to install some parts I had around
rather than hoping the regulator didn't oscillate.
I'm not sure I would count on that heatsink at 1.5A, but if your
application, like mine, is not very demanding then it should be no
problem.
Also, I may go in later and tune the pot so that the bottom 1/3rd of
the travel isn't wasted. As designed with the pot below this point the
lights are off, so only partial rotation will control the entire
intensity range.
Jim Daniels
Message 23
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| Subject: | Encoder / Transponder domino failure? |
--> AeroElectric-List message posted by: SportAV8R@aol.com
Okay, gentlemen: help me puzzle this out...
A few weeks ago my RMI microEncoder became erratic in flight, cycling into test
mode and shutting itself off repeatedly. Finished the flight with no mode C
squawk but a normally-functioning transponder; at least I was seeing the interrogation
light come on at the expected level of activity. Tear-down inspection
of the RMI revealed a rattle in the case, turned out that two screws holding
down a heat sink had shed their nuts and lockwashers and fallen free. The screws
were in the bottom of the can, but the nuts and washers had been dancing
around on the solder-side of the lower circuit board, apparently causing the gremlin-action
in flight.
The screw integrity issue seems to have come from the insulating shoulder washers
compressing/separating into sheared-off fragments and exhausting their pre-load
on the fasteners, which then vibrated loose. It was a simple fix (Loc-Tite)
and the bullet-proof uEncoder came back to life and has acted fine since.
Later on, my buddy says he can't see me on his TCAD, and I start to notice the
interrogation light is not doing anything on the next few local flights. That's
odd; I usually get pinged at this altitude at the home field. A cross-country
trip just outside some major Class C confirms that the Garmin GTX 320 is apparently
deaf or mute, and we have a problem.
Dilemma: garmin will bench test it for me and fix it for $250. Cost is the same
even if the unit checks out okay. I know from the startup light that it has
power. How can I be sure it's not a coincidental feedline/antenna problem without
spending 250 bucks?
All I can speculate is that somehow during all the electrical mayhem in the encoder
while the screws were loose, some voltage got into the XPDR via the data
bus from the encoder and let the smoke out of some component. It seems unlikely
that a stray voltage on those pins would damage the very guts of the transponder
rather than just the mode C part, but I'm just musing in the dark.
Ideas appreciated.
I know of a nearby avionics shop that might be willing I will probably give them
a call tomorrow.
-Bill B
RV-6A
Message 24
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| Subject: | Re: Battery Contactor vibration problem |
--> AeroElectric-List message posted by: Vince Ackerman <vack@mac.com>
I glad (sort of ) that it wasn't just me and you could duplicate what I
did with a little more eloquence. The bottom line for an aircraft
(helicopter ) like mine, with FADEC's that cannot tolerate any power
interuptions, is still a question in my mind. What are the options?
Give a vibration that could disrupt the contactor, what could bridge
the millisecond power interuptions that would keep the computers from
shutting down and rebooting? Some sort of capacitor? A rubber mount for
the contactor? I'm not an electrical engineer by any stretch, so your
suggestions would be most valuable.
Thanks
Vince
On Monday, October 20, 2003, at 02:19 PM, Robert L. Nuckolls, III wrote:
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <bob.nuckolls@cox.net>
>
>
> Yes. Went to the workbench and wired up your Cole-Hersee
> contactor to a power supply and load resistor. Powered
> it up at 10V and 15V. Lightly tapped with a
> hammer and took the following response graphs:
>
> http://www.aeroelectric.com/temp/CH10V.jpg
> http://www.aeroelectric.com/temp/CH15V.jpg
>
>
> Dug out a RBM/Stancor part and repeated the experiment:
>
> http://www.aeroelectric.com/temp/RS15V.jpg
> http://www.aeroelectric.com/temp/RS10V.jpg
>
> Both brands of contactor are similarly affected
> by the hammer taps.
>
> After some reflection, I'm not surprised. While
> relatively light taps were used, a rigid metal
> mass striking another rigid metal mass can easily
> generate acceleration pulses (shock)
> of 100-1000G . . . The pulses are very short
> meaning that the energy transferred is low . . .
> but instantaneous force to components mounted
> within can be substantial.
>
> Forgive the non-quantified words above like "light"
> "short" "substantial" and "low" . . . I don't have
> the tools in my shop to instrument and quantify
> these phenomenon. However, I will invoke some hands-
> on experience with qualifying flight hardware at
> shock levels of 400G or more . . . it's NOT difficult
> to impart stimulus of 100 to 1000G in these situations.
>
> You'll note that documented disruptions are on the order
> of 1 to 3 milliseconds in length and steep sided.
> The steep sides says there was no arc forming in the
> contact gaps. You will also note that each event
> generated 2 to 5 circuit interruptions (contact bounce).
>
> Playing with the test fixture demonstrated that the
> number of interruptions per event had more to do with
> tapping-technique and chance than with any observable
> difference between the two brands of contactor.
>
> Okay, what's this all mean?
>
> (1) let us note that both contactor designs are
> at least 50 years old and no doubt been produced in
> millions of parts. If the parts are still in production,
> it's a fair assumption that the vast majority of
> users have experienced satisfactory service life
> WHETHER OR NOT they were aware of the propensity for
> bouncing contacts if tapped with a hammer.
>
> (2) the stimulus is not cyclical vibration but short,
> high-g shocks . . . a stimulus rarely found in an
> airframe or any other vehicle.
>
> (3) Interruptions of 3 millisecond interruptions and
> more are EXACTLY the kinds of power input perturbations
> that DO-160 tells us to EXPECT and be prepared to
> shrug it off.
>
> (4) the act of rotating the mounting axis of a contactor
> to ward off evil shocking spirits is not useful
> . . . aerodynamic linear g-loads can be reasonably
> expected to maximize through the vertical axis . . .
> mechanical shock may come from any direction.
>
> Bottom line:
>
> If you hammer-tap any contactor of this genre, you'll
> undoubtedly produce the same kind of interruptions
> that Vince noted and brought to our attention. I'm
> pleased to have an opportunity to compare two
> brands of similar devices and to have a reason to sit
> down and consider their relative design features.
> It's useful to make a new discovery of old data and
> understand its significance in the design and operation
> of our airplanes.
>
> What I've learned today doesn't change my recommendations
> for using these el-cheapo contactors in a well-considered,
> failure-tolerant design. I continue to be of the opinion
> that they will give good value performance free of extraordinary
> risk when mounted in any orientation for ease of installation.
>
>
>> Thanks again
>>
>> Vince
>
> Thank you sir! I figure any day you go to bed knowing
> something you didn't know yesterday is a good day. This
> would not have come to light without your observations
> and a willingness to ask the question.
>
> I cranked though a number of plausible but way-out-in-left-
> field scenarios to explain what you observed. It was quite
> useful to put all those hypotheses in the trash and
> discover the truth . . . and best yet . . . to find that
> it didn't matter!
>
> Bob . . .
>
Message 25
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| Subject: | Small aux battery: diode vs. relay |
--> AeroElectric-List message posted by: Geoff Evans <hellothaimassage@yahoo.com>
Bob.
After reading this list for a year or so and perusing the archives, I've
narrowed down my my proposed electrical system from a "that would be nice to
have" design to a "this is all I really need to get the job done" design.
I'm (now) planning dual electronic ignitions, one main battery, and one small
aux battery which ONLY supports the second ignition and is not used for
starting. I might install a SD-8 later, but I don't think I need that for my
VFR ship at this time.
Anyway... You made a comment in one of the archived messages that you prefer
"hard" connections to diodes in this situation. Why is that??
I'm trying to decide between a S704-1 relay with manual control of the small
aux battery bus tie, or a schottky diode to provide current for charging of
the aux battery and operation of the second ignition.
The diode is attractive because it reduces the possibility of pilot error
(like cranking the engine with the aux battery connected) and it reduces the
parts count. However, the relay is attractive because it gives you more
control over the system and doesn't produce the voltage drop that a diode
would. So... Why do you prefer "hard" connections to diodes?
Also... I understand that small aux batteries won't accept a large charging
current, so fat wires are not necessary. You have stated in the past that 18
or 20 AWG wire is fine for charging only a small aux battery and running one
ignition. However, how does one KNOW for sure how much charging current the
small (4.5 AH) battery will accept? The distance between my batteries and
their relays/contactors is less than 6", so I don't plan to protect those
wires. How do I know that I won't smoke the wire going to the aux battery if
(for some strange reason) it is accepting a large charge?
Thanks.
-Geoff
RV-8 QB
__________________________________
Message 26
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| Subject: | Neutral cure silicone and urethane adhesive |
--> AeroElectric-List message posted by: "Rob W M Shipley" <rob@robsglass.com>
Larry,
The automotive urethanes accept auto paints only too well. Body shops are extremely
proficient at painting over a nice cleanly cut layer of urethane left on
the vehicles pinchweld ready for applying the new bead of adhesive and the new
windshield / backglass / quarter window. (Perhaps you can guess I own an autoglass
company. ;-]). They are similar in texture to a stiff rubber and as such
might shed paint if flexed. I would not consider them a good structural foundation
for paint unless used as a thin layer - perhaps 3/32" or less. Smoothing
them is something of an art and if you want more detailed information you
can call me at 619 697 9192 any evening (CA time).
Rob
--> AeroElectric-List message posted by: Larry <larry@grrok.com>
??Will these urethane adhesives hold paint??
At 05:34 PM 10/16/03, you wrote:
>--> AeroElectric-List message posted by: "Rob W M Shipley" <rob@robsglass.com>
>
>It performs just as well as it's acetic acid curing counterpart. When you
>ask if it is "as strong" as the other form do remember that none of the
>silicones should be viewed as a structural adhesives. If you need a
>waterproof adhesive/sealer which has significant strength you need to be
>considering urethane adhesives. These are used to install auto
>windshields and in this application must retain the windshield in the
>event of an airbag deploying. This can place an almost instantaneous load
>of up to half a ton of outward pressure. I know of one builder who used
>this type of adhesive to attach hi canopy to the frame of a slider and I
>am actually considering the same method for my 9 tipper.
>Fly safe
>Rob
Message 27
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| Subject: | Source for BNC adapters? |
--> AeroElectric-List message posted by: HCRV6@aol.com
Bob or anyone: Does anyone know of a source for the type of BNC adapter
that Garmin uses in their new transponders and nav/com units (other than
direct from Garmin that is). These are the type that install in the chassis with
a
snap ring and have a plug in socket on the inside to mate with the unit and a
BNC jack on the outside.
I want to replace the solder type antenna coax snap ring adapters that came
with my KX-125. I called John Stark, but he said he has been looking for them
also with no success so far.
Harry Crosby
Pleasanton, California
RV-6, firewall forward
Message 28
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--> AeroElectric-List message posted by: <mjheinen@adelphia.net>
Is there a solid state dimmer available yet that only uses the power needed to
light the bulbs without spilling over excess as heat?
>
> From: Jim Daniels <jwdanie@comcast.net>
> Date: 2003/10/20 Mon PM 09:58:16 EDT
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Dimmers
>
>
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