Today's Message Index:
----------------------
1. 05:24 AM - engine compartment wiring (bob noffs)
2. 07:09 AM - Re: No sidetone driving me insane! (keithmckinley)
3. 07:17 AM - Re: engine compartment wiring (Ron Shannon)
4. 08:12 AM - Re: engine compartment wiring (Ken)
5. 10:13 AM - Re: Re: High resistance pops breaker? (Robert L. Nuckolls, III)
6. 11:35 AM - Re: High resistance pops breaker? (Robert L. Nuckolls, III)
7. 11:51 AM - Re: Printed circuits (Robert L. Nuckolls, III)
8. 11:56 AM - Re: Bendix IN-224A Pinout or wiring diagram (Robert L. Nuckolls, III)
9. 12:24 PM - Re: Molex wire splice recall (Robert L. Nuckolls, III)
10. 09:02 PM - Re: Printed circuits (Ron Quillin)
11. 09:24 PM - Tachometer Noise (Michael Forhan)
12. 10:37 PM - Re: Tachometer Noise (jetboy)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | engine compartment wiring |
hi all, what is everyone doing to secure wires in the engine
compartment? wire ties rated for the high temp. are made of gold [or
petroleum products]. are the ''lacing '' materials suitable?
any input is appreciated.
bob noffs
woodruff, wi.
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: No sidetone driving me insane! |
THANK YOU JOE GARNER!
You were absolutely right. The person who wired this system used the speaker out
terminal to the headsets instead of the headset jack out.
Problem solved, life is good!
Next beers are on me!
Keith
--------
Wizard
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 0074#200074
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: engine compartment wiring |
On Sat, Aug 23, 2008 at 5:20 AM, bob noffs <icubob@newnorth.net> wrote:
> hi all, what is everyone doing to secure wires in the engine
> compartment? wire ties rated for the high temp. are made of gold [or
> petroleum products]. are the ''lacing '' materials suitable?
> any input is appreciated.
> bob noffs
> woodruff, wi.
>
Bob,
As you know, there are several considerations, including potential damage
from vibration, chafe, high heat, fire, etc. I have used fire retardant
loom/spiral wrap and/or sleeving for all significant bundles, and everything
on or near the engine -- mostly tied together and tied down with Tefzel tie
wraps from Steinair. In two locations, I've supported large, enclosed
bundles with double Adel clamps, in both cases to ensure clearance from
things below (a mixture cable, and an intake hose.) For two wire bundles on
the firewall (both inside fire retardant materials) I've used single Adel
clamps. One small wire bundle (oil pressure & temp) that runs under the
cylinder heads and not too far from exhaust pipes is in Thermo-Sleeve, for
extra protection from constant high heat in that area.
Normal lacing is not appropriate for FWF, where it can get quite hot even in
normal operation, to say nothing of fire situations.
By all means, consider the wiring standards in AC43.13. They include
standoffs, separation from fuel lines or other plumbing & heat sources,
mounting requirements, bend radius issues, etc. You may want to depart from
some of those standards here and there, but it's a good place to start.
There are several pictures of my FWF wiring, which is nearing completion, on
my web site.
Ron
http://n254mr.com
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: engine compartment wiring |
Bob
FWIW I used Adel clamps for heavy cables, bundles, and where it seemed
appropriate. With dual EFI, I have a lot of wiring and I've had no
problem at all where I've tied things with lacing. I also have a fair
bit of the silicone self adhering tape protecting things where there is
risk of chafing. In fact silicone tape under the lacing seems to work
well as the lacing then grips well and there is no chafing that I can
detect. I guess I have one or two nylon wire ties as well (silicone tape
under them) but they have stood up fine for a couple of years now. They
are not exposed to exhaust radiant heat. After looking carefully at some
certified installations, I concluded that almost anything you are happy
with is probably just fine if you inspect it occasionally...
Ken
bob noffs wrote:
> hi all, what is everyone doing to secure wires in the engine
> compartment? wire ties rated for the high temp. are made of gold [or
> petroleum products]. are the ''lacing '' materials suitable?
> any input is appreciated.
> bob noffs
> woodruff, wi.
>
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: High resistance pops breaker? |
At 05:24 PM 8/20/2008 -0700, you wrote:
>
>I was going to test this but it soon became apparent that the problem was
>beyond mere testing.
>
>One consideration that I have not seen is that breakers wear out. "I
>squared T" or current squared X time" is how breakers blow, but the
>problem has many back alleys of complication. Once a beaker has tripped at
>above a specified current, the breaker will be degraded and trip
>thereafter usually at a lower current. All breakers have a one-time
>maximum trip current. (This is what is wrong with crowbar OVPs).
I've heard this idea handed down from sage-to-
acolyte over campfire and beers for decades. My
brother-in-law was told this by a journeyman electrician
while he was getting his ticket to string wire . . .
but my friends at Cutler-Hammer, Klixon, Mechanical
Products and others cannot embrace this legend.
I'll refer the readers to Mil-C-5809G available at:
http://www.aeroelectric.com/Reference_Docs/Mil-Specs/5809G.pdf
and specifically to paragraph 4.7.14 where products
qualified to military applications (and most commercial
aircraft applications) are subjected to huge interruption
current tests from both a closed condition (breaker opens
due to operational fault) and open condition (breaker
is closed into a pre-existing fault) trip test.
Referring to one of many specs for the breakers
recommended for aircraft at:
http://www.aeroelectric.com/Reference_Docs/Circuit_Breaker/MS3320.pdf
In Table III we find the range of interrupt current tests
that each size breaker is subjected to. Note that
the numbers (particularly categories C & D for 28v
systems) are in the thousands of amps. Many times higher
than stress to a crowbar-tripped breaker. Yet after being
subject to these tests, they are required to past the
200% overload trip calibration.
An interesting feature of the interrupt current test,
only one or two devices out of a larger QPL sample
are subjected to this test while greater numbers of
parts are tested more rigorously for other qualities.
Could it be that risk for failure due to interruption
current stress is so low that folks never seem to fail
it . . . while other qualities of a breaker demand
closer monitoring?
For the benefit of our readers, know that for a
manufacturer to sustain membership in the club of qualified
suppliers, a sampling of their continuous production output
receives the same battery of tests every so often in their
production cycle. For devices strongly affected variables
in materials and process, qualified products lists (QPL)
are maintained wherein the various manufacturer's pay their
procedural dues to stay listed. Fall off that list and the
military cannot purchase your product no matter how good
you were when initiated into the club.
I have offered this documentation before and not
one of my detractors had commented on it. For folks
who are so invested in manufacturer's data sheets
as infallible, I'm mystified as to the ease with which
repeatable experiments levied by qualification test
plans and membership on qualified products list are
so easily ignored . . .
Finally, 5A Klixon breakers incorporated into production
test stands for alternators/regulators fitted with
crowbar OV protection were subjected to hundreds
of crowbar events over a period of years . . . with
no observed degradation of breaker performance. It would
be interesting to retrieve one of those breakers and
run the 200% trip time test on them.
>So--can a landing light blow a circuit breaker below the specified lamp
>current if there are some high-resistance connections? My guess is "yes"
>but it depends on the breaker, the lamp, the nature of the loose
>connections, the wire, and myriad other variables. The likely culprit is
>the breaker.
Hmmmm . . . . connections, lamp, breaker, wire, and
"myriad of other variables". This shopping list of
'maybes' implies a sage understanding but without
transfer of understanding to your readers.
How can the condition of wire exacerbate breaker
tripping? If the breaker is not undersized by error of
system design, how does the breaker itself participate
in a scenario of nuisance tripping? 99.999% of all
breakers run the lifetime of an airplane never being
called upon to do their job. Qualification demands
thousands of demonstrated operations before they are
allowed on the airplane. Share with us a rationale
for your assertion: "likely culprit is the breaker".
If we are deprived of some knowledge/understanding
of physics, repeatable experiments or artfully analyzed
failures, please help us out.
Bob . . .
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: High resistance pops breaker? |
At 03:03 PM 8/20/2008 -0400, you wrote:
>Bob,
>
>If I understand correctly, as the landing-light-retract motor slows due to
>increased circuit resistance (and thus lower voltage at the motor), the
>motor current will not increase because the torque required to operate the
>retract mechanism is the same as before.
Correct.
> The power (watts) of the motor is less because power equals speed times
> torque, and the speed has decreased. The total energy used to operate
> the mechanism will be about the same because it is a function of power
> and time.
Correct.
>Even though the motor is less powerful operating at a lower voltage, it
>runs for a longer time and thus uses about the same total power as it
>would operating at a higher voltage for a shorter time.
Correct.
>It seems to me that a slower motor develops less back-EMF and therefore
>would allow more current to flow.
If all other variables are the same, then the only way the motor
slows down is by increasing the load on the motor. Increased
torque translates to increased current. Now, the only reason
the motor slows down is because of resistance in the loop drops
the effective motor-supply voltage due to losses in the system.
> But on the other hand, higher resistance in the circuit counteracts
> that. I do not know how to calculate that, so I will take your word for
> it that the current stays the same.
I appreciate your profession of faith but it is
not necessary to make your own understanding
subservient to mine. Take a peek at:
http://www.aeroelectric.com/Reference_Docs/Misc_PDF/Motors_as_Energy_Converters.pdf
This is but one of thousands of down-loadable
treatments of this topic available on the 'net.
I just got home from a three day trip to a client's
facility to bring this same information to their
non-electrical engineering staff. Everybody walked
out of the discussions with a good working knowledge
of motor performance.
Note that the speed torque curve for this motor
has SLOPE. I.e, more torque results in increased
current flow which increases the drop in effective
applied voltage that is manifested by a lower RPM.
The speed torque curves for a motor ASSUME constant
terminal voltage at the motor. This is a necessary
constraint on scope of data because the motor
manufacturer has no control over EXTERNAL resistance
in the system. However the system designer is
obligated to include both internal and external
resistance to anticipate as-installed motor
performance.
Stall torque (and current) is a function of applied
voltage divided by total resistance. This is plain
ol' Ohm's law. One may readily deduce that the slope
of the curve is made steeper by increasing total
resistance; flatter by reducing total resistance. But
the current demanded by the motor for any condition
is firmly locked to effort in the motor shaft.
Note that for any given torque, there is a predictable
level of current demanded by the motor. Whether or not
the motor can sustain speed necessary for performance
at that load is directly affected by TOTAL circuit
resistance. The astute system designer draws a NEW
speed torque curve that has the same no-load speed
but a steeper slope and therefore lower stall torque
combined with a higher sensitivity of speed to torque.
If we could build a super-conducting motor, the
speed-torque plot would be a horizontal line. But
if the motor were super-conducting and external
wiring was not, the "flat line" motor would perform
to a new curve that has some small, but predictable
and perhaps significant slope.
>Suppose there are no high resistance connections and one compares the
>motor current at two different voltages, say 14 volts compared to 11 volts
>with a failed alternator. What happens to the motor current as the supply
>voltage drops? From what you wrote, I assume that the current will not
>increase.
Correct. The speed of the motor is given by:
RPM = (Eapplied - I*Rtotal)/(Volts/RPM)
Where
I*Rtotal describes depression of effective voltage
due to losses.
Volts/RPM describes the CEMF constant Ke
and I is a function of torque at the motor shaft.
One may easily deduce that with all other things
constant, an increase in torque reflects as a
proportionate increase in I resulting in more
losses through R. Speed MUST therefore go down
as the effect of a decrease in effective operating
voltage.
Here's a more detailed discussion of motor
characteristics for those who are interested.
http://www.aeroelectric.com/Reference_Docs/Misc_PDF/Motors_as_Energy_Converters.pdf
> I am not trying to contradict anything that you said. I just want to
> understand. My experience has been with AC motors that try to maintain
> their synchronous speed by increasing current draw when heavily loaded or
> when operated at a lower voltage.
AC motors are more like a transformer-in-motion. Shaft
effort is a function of voltage induced in rotor conductors
by the low frequency AC difference between rotating
magnetic field in stator windings as "primaries" and
conductors in the squirrel cage as "secondary" windings.
The coupling coefficient for energy rises as the DIFFERENCE
frequency (hence increase in delta-velocity between ac
mains stator and induced currents in rotor) get larger
when rotor speed goes down due to loading. The physics which
control behavior of the induction motor are quite apart from
that of DC motors. While the two technologies operate on the
same rudimentary rules of magnetics and current flow, one
cannot accurately predict all behaviors of one from even the most
complete understanding of the other.
> DC motors do not have any certain speed that they strive for.
Yes, they do. In AC motors, no-load (synchronous) speed
is driven by line frequency and numbers of poles in the
stator windings. In a DC motor, no-load speed is a
function of applied voltage divided by Ke when losses
are quite low. As I mentioned earlier, if losses could be
driven to zero, then speed torque would be a flat line
defined by Eapplied/Ke. I think there's a TON of confusion out
there about DC motors based on folks real life experiences
and observations of AC motors. They're entirely different
technologies.
Bob . . .
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Printed circuits |
At 06:20 AM 8/22/2008 +0200, you wrote:
><catignano@tele2.it>
>
>Bob,
>
>I know that this subject has been discussed before, but can't find it.
>In short, what do you recommend to clean printed circuit boards after
>assembly?
There are some solders that offer water soluble fluxes but
unless you went to special effort to acquire this product,
you're not going to be able to simply run your boards through
the dishwasher.
I've removed "plastic" fluxes with carburetor cleaner in
spray cans from Wally World. I've bought it by the case
for under $1 a can. This is essentially strong but not
terribly aggressive solvent like lacquer thinner. You can
also try mild solvents like brush cleaners that are not
unlike starter fluid for charcoal. Denatured alcohol used
in shellacs is a good mild solvent that may work with your
flux.
Be cautious with aggressive solvents like acetone, mek
methyl chloride, etc. These can attack the binders in your
board's fiberglas as well as some finishes and plastics
used to fabricate the components. I use aggressive solvents
for spot cleaning . . . dampen a q-tip and rub locally.
You can use a brush dipped in solvent to dissolve flux
residue and flotsam it captures. Do a final rinse with
new, clean solvent and blow dry with your shop air or
a heat gun set on cold. After all acceptance tests are
complete, mask off connector pins and rotating parts.
Spray with a coat of Krylon Crystal Clear Glaze.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Bendix IN-224A Pinout or wiring diagram |
At 02:58 PM 8/21/2008 -0400, you wrote:
>ATTGNS" <rc8653@att.com>
>
>I need a pinout for the IN-224A that we are trying to use with a KX-170B
>and KNS-80. Owner did not have an indicator. Seems the ocean swallowed
>his last plane. Anybody have that pinout?
Didn't find a IN-224 but did find IN-244. You can get it
at:
http://www.aeroelectric.com/Installation_Data/IN-244.pdf
Hope this is the one you're really looking for!
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Molex wire splice recall |
At 08:11 PM 8/20/2008 -0600, you wrote:
>1. Electrical Wire Splices Recalled Due to Shock and Fire Hazards
>
<snip>
>Hazard: The splice can fail to hold the wires adequately together, posing
>a shock and fire hazard to consumers.
>
>Incidents/Injuries: Gardner Bender has received one report of a recalled
>butt splice failing to hold wires together. No injuries have been reported.
>
>Description: The recalled butt splices are used to connect electrical
>wires to one another. They are typically used for wiring small electrical
>appliances, like audio equipment, or in automotive applications. The
>splices are yellow insulated vinyl and measure about one inch long and
>inch wide. They were intended for use with 12-10 AWG wire. 12-10 is
>stamped on the side of the splices. Model numbers 10-126, or 21-126, and
>Gardner Bender are printed on the product's packaging. They were sold in
>packages of 8 or 50.
>
>Sold at: Electrical distributors, hardware stores, and home centers
>nationwide from June 2005 through April 2008 for between $1 and $5.
Well gee . . . do we (or anyone else) know if this
splice was properly applied; right wire size, right
tool, right process?
There is MUCH more to this story than is knowable from
the announcement. A review of Gardner Bender's tools
at:
http://www.gardnerbender.com/pdf/products/Hand_tools.pdf
suggest that their termination/splicing products at:
http://www.gardnerbender.com/pdf/products/Terminals_wire.pdf
show that these are low-tech devices and tools not
intended to deliver consistent, gas-tight crimps combined
with insulation support. None of these products and tools
are suited for use in anything but the most benign of
environments and especially not with solid wire. It would
not surprise me that the failure cited in the recall was
a result of misapplication of wire, terminal and/or tool.
To initiate a recall on a single incident is suspicious
-------------
If you do not tug test a crimped connection before putting it in service,
you will have a failure over time, guaranteed.
My personal reflection on this is as we get older, that old nemesis
arthritis starts to kick in and we just do not squeeze the Sta-Kon pliers
with the crushing grip of our youth.
Joe Motis
Joe, the tools and materials we SHOULD be using will conform
to performance standards set by design goals of the terminal
designer as described in:
http://www.aeroelectric.com/articles/terminal.pdf
applied to STRANDED wire with tools tested for compatibility
with both terminals and wire for achieving gas-tight
connections. No "testing" is necessary if one has done
their homework before hammering on the airplane.
The Gardner-Bender products were not designed to those
goals nor do their tools provide sculptured dies
closed against hard stops with ratcheting handled
tools.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Printed circuits |
At 11:48 8/23/2008, you wrote:
> Be cautious with aggressive solvents like acetone, mek
> methyl chloride, etc. These can attack the binders in your
> board's fiberglas as well as some finishes and plastics
> used to fabricate the components. I use aggressive solvents
> for spot cleaning . . . dampen a q-tip and rub locally.
NASA really likes Isopropyl and Ethanol; both are spec'd in
NASA-STD-8739.4 for PWB fabrication and cleaning.
> You can use a brush dipped in solvent to dissolve flux
> residue and flotsam it captures. Do a final rinse with
> new, clean solvent and blow dry with your shop air or
> a heat gun set on cold. After all acceptance tests are
> complete, mask off connector pins and rotating parts.
> Spray with a coat of Krylon Crystal Clear Glaze.
Also consider HumiSeal 1B73 for an Acrylic MIL spec conformal. Used
it for years.
Chase also makes a newer Acrylic 1B31 that's easier to work with, and
a polyurethane 1A33.
All three are qualified to MIL-I-46058C.
http://www.humiseal.com/
Ron Q.
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Tachometer Noise |
I have a Jabiru 2200 engine and a VDO tachometer. I'm coupling one alternator lead
to the tacho signal input. It works fine at lower rpms, but at about 2000
RPM it becomes very erratic. I searched around the internet and found some discussion
of the problem as being noise related with general suggestions to install
noise filters, series resistors, etc. to correct the problem but few details
on the circuit configuration. The most detailed info I saw described a 1 uF
coupling capacitor between the alternator and the tach with a 10K resistor and
a clamping diode connected to ground on the tach side of the capacitor. Has
anyone on the list tackled this problem?
Thanks,
Mike
Message 12
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Tachometer Noise |
The earlier Jabirus used a magnetic pickup at the ringear driving a VDO tach /
digital hourmeter and they later changed to the same pickup placed near metal
tabs on the flywheel (and different rpm calibration setting for this) This is
the normal way for larger diesel engines and the like.
You are likely to have trouble using the alternator wires as source because none
of them connect to ground and the regulator will cause extra pulses on the lines
as it does its job. I do connect across the windings and use a digital frequency
counter for calibration of my other system, and that works OK
Ralph
--------
Ralph - CH701 / 2200a
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 0217#200217
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|