Today's Message Index:
----------------------
1. 05:58 AM - Re Rotax Aux Alternators (irampil@notes.cc.sunysb.edu)
2. 06:09 AM - Re: Battery ground? (Mark Steitle)
3. 06:18 AM - Re: Re: Keep warm circuit for Landing/Taxi (Robert L. Nuckolls, III)
4. 06:32 AM - Re: Two Grounds? (Robert L. Nuckolls, III)
5. 07:06 AM - Re: Keep warm circuit for Landing/Taxi (Robert L. Nuckolls, III)
6. 07:32 AM - Re: AOA Comments (Fiveonepw@aol.com)
7. 11:12 AM - Re: Re: Keep warm circuit for Landing/Taxi lights (Eric M. Jones)
8. 12:40 PM - Re: AOA was Stall Horn (Jan de Jong)
9. 12:47 PM - Motorcycle generators (echristley@nc.rr.com)
10. 12:59 PM - DC motor braking diagram (James Redmon)
11. 01:11 PM - Welding Cable (Jerry2DT@aol.com)
12. 02:17 PM - Re: Tail Light - Bulb Type? (Boddicker)
13. 03:56 PM - Re: Motorcycle generators (Trampas)
14. 06:52 PM - ELT Control Access ()
15. 07:40 PM - Re: Master Switch Question (Tinne maha)
16. 07:49 PM - Re: Motorcycle generators (Ernest Christley)
17. 08:40 PM - Re: Re: Re: Keep warm circuit for Landing/Taxi (Richard E. Tasker)
18. 10:07 PM - Re: Re: Master Switch Question (Robert L. Nuckolls, III)
19. 10:21 PM - Re: Welding Cable (Robert L. Nuckolls, III)
20. 10:22 PM - Re: DC motor braking diagram (Robert L. Nuckolls, III)
21. 10:23 PM - Re: DC motor braking diagram (Robert L. Nuckolls, III)
22. 10:58 PM - Re: ELT Control Access - OT (Mickey Coggins)
Message 1
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| Subject: | Re Rotax Aux Alternators |
11/16/2004 08:57:36 AM,
Serialize complete at 11/16/2004 08:57:36 AM
--> AeroElectric-List message posted by: irampil@notes.cc.sunysb.edu
Alfred,
From all that I have gathered, you may not see more than 5-6 amps from the
BC-8 on the
standard Rotax gearbox spline shaft. You might be interested to know that
FlightCrafters in
Seffner had made a small run of custom alternators that will pump 30-40 A
from that
location. I purchased but not yet installed one on my 912S. When it is
running, I will
describe the results on the Euro list.
Ira N224XS Europa XS Motorglider (-long wings), BMA EFIS\One with
Autopilots, Airmaster
about 70 hr in flight so far
Message 2
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| Subject: | Re: Battery ground? |
--> AeroElectric-List message posted by: Mark Steitle <msteitle@mail.utexas.edu>
I found a local ACE hardware store that had welding cable on the
spool. Not sure why, but there it was.
Mark S.
At 11:35 PM 11/15/2004 +0100, you wrote:
>--> AeroElectric-List message posted by: Mickey Coggins
><mick-matronics@rv8.ch>
>
>Hi,
>
>For those of you like me without a welding supply store
>around the corner, I've ordered some welding cable
>from McMaster-Carr:
>
> http://www.mcmaster.com/nav/enter.asp?partnum=7818A18&pagenum=3142
>
>I don't have it yet, so I can't give much feedback, but it's
>there. Only costs about 0.72 USD per foot.
>
>Mickey
>
>
>At 22:51 15-11-04, Robert L. Nuckolls, III wrote:
>-----Start of Original Message-----
> >--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <bob.nuckolls@cox.net>
> >
> >
> >>Bob Hi,
> >>
> >>Can I run my #2 Battery Ground wire separately to the 0-320 motor as
> >>opposed to connecting the Battery ground lead directly to the B & C Single
> >>point ground brass bolt and Ground Strap.
> >>
> >>I have an RV-8 and, the #2 Battery Wire will not reach the B & C single
> >>point ground strip easily. Therefore I've run the ground strap and #2
> >>Batter Ground wire separately to the same connection point on the motor.
> >
> > I'm concerned that you have #2 battery jumpers. These tend to be pretty
> > stiff and increase risk of battery post breakage due to vibration.
> > I'd like to see you make new jumpers from #4AWG welding cable and while
> > you're at it, make the battery(-) cable long enough to reach the
> > firewall ground stud.
> >
> > Welding cable is easy to get, really inexpensive and nice to work
> > with! I recommend #4 battery jumpers irrespective of the size
> > of fat wires for the rest of the system. The smaller, softer jumpers
> > are much more user and battery friendly.
> >
> > Bob . . .
>
>
>--
>Mickey Coggins
>http://www.rv8.ch/
>#82007 QB Wings/Fuselage
>
>
Message 3
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| Subject: | Re: Keep warm circuit for Landing/Taxi |
lights
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
lights
At 10:29 PM 11/15/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: "Richard E. Tasker"
><retasker@optonline.net>
>
>I have to agree with Dennis. Most of your devices and ideas (Eric) are
>great, but I have to question this one. What is the advantage of this
>arrangement? It does limit the surge current a little more than the
>thermistor. But once running, the thermistor has this beat hands down!
>Assuming a 75W light, and using the 8A rated thermistor, the thermistor
>limits the surge current to about 7A and then warms up to drop about
>0.35V. This compared to your results of 6A surge with 2V drop when the
>lamp stabilizes.
>
>So the surge limits are very similar, but the steady state losses for
>the transistors are almost 6 times the thermistors!. Of course, the
>lights will last longer with the transistors since they will be running
>on a reduced voltage (dimmer).
>
>What am I missing here???
>
>Dick Tasker
Another thing to consider is what value is being added to
the system in return for the $time$ it takes to install it?
The keepwarm system seems like a useful thing to do with lamps
that are expensive and don't last very long . . . halogens
are extremely long lived compared to their ancestors. So
perhaps the best benefit that can be realized from inrush
limiting is to reduce effects of the negative going bus
voltage excursion during lamp start up. If the suggestions
offered by DO-160 for tolerating transient brownouts have
been observed, then perhaps the $time$ one expends on
current limiting for a couple of lamps is about as
well invested as putting electric door locks and keyless
entry on a dump truck.
Bob . . .
Message 4
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| Subject: | Re: Two Grounds? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 06:57 PM 11/15/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "Tinne maha" <tinnemaha@hotmail.com>
>
>List,
>
>I'm a little confused about grounding. Fig Z-11 shows what I'm
>interpreting to be both a single point groundAND a connection betweena
>metal airframe (mine is tubular steel) the negative terminal of the
>battery. Is the connection to the airframe <EM>in addition</EM> to the
>single point groundpreferred over having just a single point ground? (What
>I'm calling a single point ground is the fat cable running from the ground
>bus to the battery negative terminal)
The single-point ground is the ground bus on the firewall and is
labeled "G2". Some things like engine accessories (starter, alternator,
sensors, etc) find ground by virtue of their mounting. For the purposes
of identifying this grounding feature for which there are no alternatives,
we identify the crankcase as ground "G1" and tie it through a very
hefty conductor to the firewall ground stud G2. The panel ground
is G3 and on the cockpit side of the firewall. It's labeled differently
to differentiate its location on the cabin side of the single point
ground system . . . it would be silly to take wires from radios
through the firewall so that they could be grounded on the engine
side of the single-point ground system. The battery ground in Z-11
goes to G2, the bolt on the firewall . . . although this could
be EITHER side of the firewall depending on where the battery
is located.
Please review the chapters on grounding and noise control for
explanation of the advantages and rational behind the single
point ground system.
Bob . . .
Message 5
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| Subject: | Re: Keep warm circuit for Landing/Taxi |
lights
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
lights
At 10:17 AM 11/15/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "Dan Checkoway" <dan@rvproject.com>
>
> > Quick question about Halogens: How well do they survive in a wig-wag
>setup? is the constant on and off a problem for these bulbs?
>
>I have dual 100W halogens in my RV-7, and I leave the wig-wag on all the
>time -- cheap insurance in the see-and-be-seen dept. Pretty much constantly
>wig-wagging for 280 hours. The bulbs are still going, no failure yet.
>
>Even so, they're only 5 bucks to replace if and when one decides to go.
One might think that the constant heating/cooling cycles of a wig-wag
system is especially hard on incandescent lamps. Tests I've run on
the workbench show that the thermal mass of a halogen lamp filament
is so high that it's still quite hot when the next ON cycle starts.
The cold-filament inrush indicative of very high thermal stress simply
isn't there. There's no reason to expect severe shortening of a halogen's
already long life when using them in a wig-wag system.
Bob . . .
Message 6
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| Subject: | Re: AOA Comments |
--> AeroElectric-List message posted by: Fiveonepw@aol.com
Hmmmm..... I re-located my pitot from underwing per plans to extreme left end
of wing at front of LE at 110 hours and have seen no change to any IAS, top
speed, stall, approach etc. It is angled down approx. 7 degrees from
chordline. Also experimented with length, from about 3" to 6" without noticeable
change. Perhaps having it mid-span would be different?
Just another data point...
Mark Phillips -6A, Columbia, TN
In a message dated 11/15/2004 7:59:59 PM Central Standard Time,
EMAproducts@aol.com writes:
If you think about it, the
advantage of the under wing pitot tube is that the airflow is always
flowing about parallel to the under side of the wing. Because of this
the airspeed indication (IAS) is accurate no matter what the angle of
attack (AOA).
>>>>Basically true, regardless of this fact many production planes still
insist in putting the Pitot out in front of the wing (less likely to get
people
damage I guess
Message 7
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| Subject: | Re: Re: Keep warm circuit for Landing/Taxi lights |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: "Richard E. Tasker"
<retasker@optonline.net>
>>What am I missing here???
You are missing the fact that I pushed the send button too early and lived
to regret it. The 2V is saturation voltage not Vdrop across the thing. My
fault. And it was past my bed-time. And I've been breathing fumes.
Thermistors are great but they get their low resistance only when very hot.
For a Keystone CL-10 with a 75W lamp (let's say 6A steady state). R=XI
Y
where X=0.50; I= 6; Y= -1.18 R=0.06. So W=36 x 0.06=2.2W. And that makes the
nickel-sized part very hot with no hope of cooling it off.
Why use the LM395T? The LM395T has a Vbe voltage of 1.125 V at 2A (current
limit) and decreases below its current limit. (e.g. 0.90V at 1.2A). So we
have a couple watts for a second when the lamp is first turned on, then
about 1W dissipation when the lamp is on steady. Since these operate in
parallel, it's a pretty good way to limit the lamp current at start-up. For
a 75W lamp, use three. These would dissipate about as much as the
thermistor, but you can cool them off! Digikey wants $3.38 each but my guess
is that they can be gotten for a buck each if you search around. I think it
is true to say that there is no lower-loss method of linear current
limiting. And using them is at least as simple as using thermistors.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
Message 8
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| Subject: | Re: ectric-List:AOA was Stall Horn |
--> AeroElectric-List message posted by: Jan de Jong <jan.de.jong@xs4all.nl>
I don't have an axe to grind, but having looked at AoA systems I do have
an opinion on the LRI.
The LRI measures (stall AoA - actual AoA) x impact pressure . Impact
pressure is the same, in practice, as dynamic pressure and proportional
to airspeed squared.
Have a look at
http://naca.larc.nasa.gov/reports/1926/naca-tn-250/
The subject is the influence of the size of orifices on pressure
measurements. The experimenter uses a 1 inch diameter cylinder and
measures surface pressure as a function of angle with the incident
airflow. Figures 6,7 and 10 show pressure coefficient (pressure divided
by dynamic pressure) as a function of angle. What is interesting is that
the dependence is approximately linear in the range of 15 - 55 degrees.
So if you had such a cylinder, put orifices at +35 degrees and -35
degrees, measured the differential pressure and divided that by the
impact (pitot - static) pressure you would have a pretty good -20
degrees thru +20 degrees AoA meter. You would zero it (by turning the
cylinder) at 0 degrees of AoA.
The LRI uses this type of measurement but zeroes the "cylinder" at stall
angle.
Also, the LRI does not divide by impact pressure.
Which leads me to the opening statement about what the LRI measures.
So:
- at constant airspeed it measures AoA reserve
- at constant AoA it measures airspeed squared reserve
- in general it measures lift reserve: the lift you could add, at any
present airspeed, by increasing the AoA to stall AoA; the differential
pressure gauge can be linearly scaled in newton/lbsf multiples, the
multiples depending on the lift characteristics of the wing.
- it does this independent of acceleration and aircraft mass
There are 2 problems:
- at increasing acceleration / aircraft mass a certain lift reserve
indication represents a decreasing reserve of AoA or airspeed: a lift
reserve indication representing 4 degrees of AoA reserve (or 10 knots of
airspeed reserve, f.i.) at 1G represents 1 degree of AoA reserve (or 6
knots of airspeed reserve, f.i.) at 4G.
- configuration dependence: flaps should change the lift scale, but
would most likely not influence the all important zero-setting (stall
AoA) much.
My conclusion:
- an excellent stall proximity landing aid for the landing configuration
- after verifying configuration independence of the zero setting: a
trustworthy general stall proximity indicator but giving less advance
warning as acceleration increases.
All a bit off-topic ofcourse.
Cheers,
Jan de Jong
Message 9
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| Subject: | Motorcycle generators |
--> AeroElectric-List message posted by: echristley@nc.rr.com
Background: I've been looking at motorcycle
generators as an easy way to push electrons around
an airplane. These things are basically a bunch of
coil on a ring that is mounted to the body, with a
shaft mounted "cup of magnets" that spins around the
coils.
Interesting part: One of the sites describing the
regulator said that it was basically a big resistor.
The generator always produced the same Watts of
energy (dependant upon engine RPM), but any that
aren't needed by the system are just converted to
heat through the regulator. The generator is self
limiting as long as it isn't overspeed. The magnets
are only so strong, so it isn't capable of
generating enough current to damage itself. This
differs from the alternator where the magnets are
replaced with a field coil that can basically create
a magnet capable of destroying the unit.
Small questions: When we talk about the PM
generators/alternators like those sold by B&C, is it
the same basic technology (ring of coils in a can of
magnets)?
Is the same type of dump-excess-to-ground regulator
used?
The Big Question: If you install one of the PM
electron pushers, would it not make sense to set its
voltage higher than any alternator? That is, make
it direct all of it's energy into useful work before
an alternator kicks in.
Message 10
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| Subject: | DC motor braking diagram |
--> AeroElectric-List message posted by: "James Redmon" <james@berkut13.com>
Can someone point me to the circuit diagram (or provide it) that shows how
to hook-up a trim switch and polarity reversing relay deck to a DC motor
such that the motor's power leads are connected together to provide motor
braking - at least I think that was how it went. I remember seeing it
somewhere, can't remember if I saw it in the "connection" or elsewhere. I
think the example was a flap extension hook-up I saw.
My hangarmate borrowed my electrical bible...(sigh)
James Redmon
Berkut #013 N97TX
http://www.berkut13.com
Message 11
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--> AeroElectric-List message posted by: Jerry2DT@aol.com
Bob and all..
I bought some welding cable, was going to use it until I snipped a small
piece and dipped it in gasoline for an hour. Gas pretty much melted the
insulation, so wondering what other hydrocarbons like engine oil might also do...
Comments?
Also, when you say "Battery jumper", what does this term refer to? Thanx...
Jerry Cochran
> I'm concerned that you have #2 battery jumpers. These tend to be pretty
> stiff and increase risk of battery post breakage due to vibration.
> I'd like to see you make new jumpers from #4AWG welding cable and while
> you're at it, make the battery(-) cable long enough to reach the
> firewall ground stud.
>
> Welding cable is easy to get, really inexpensive and nice to work
> with! I recommend #4 battery jumpers irrespective of the size
> of fat wires for the rest of the system. The smaller, softer jumpers
> are much more user and battery friendly.
>
> Bob . . .
Message 12
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| Subject: | Re: Tail Light - Bulb Type? |
--> AeroElectric-List message posted by: Boddicker <trumanst@netins.net>
Jon,
I have a Whelen tail light also. Part# A555.
It is a push in bulb much like the small bulbs on a string of Christmas
lights. The power is picked up by friction fit, with exposed wire mating
with a small clamp type socket. Replacement bulb No. A508-14.
Hope this helps.
Kevin Boddicker
Luana, Iowa
Tri Q200 N7868B
Building
on 11/13/04 2:32 PM, Jon Finley at jon@finleyweb.net wrote:
> --> AeroElectric-List message posted by: "Jon Finley" <jon@finleyweb.net>
>
> Hi all,
>
> I've got a little project going and I'm not near the airport to check on
> this myself.
>
> I have Whelan position lights. Could someone please tell me whether the
> tail light is the type of bulb with the two little nubs (that retain the
> bulb in the socket) the same distance from the 'end' of the bulb or are
> they off-set (like the multi-filament break light bulbs)??
>
> Thanks so much!!
>
> Jon Finley
> N90MG Q2 - Subaru EJ-22 DD - 465 Hrs. TT
> Apple Valley, Minnesota
> http://www.FinleyWeb.net/Q2Subaru
>
>
>
>
>
>
Message 13
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| Subject: | Motorcycle generators |
--> AeroElectric-List message posted by: "Trampas" <tstern@nc.rr.com>
All PM generators are about the same, most regulators are shunt regulators
like you described.
The problem with PM generators is that they do not output enough voltage to
charge battery till RPMs are relatively high.
Regards,
Trampas
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
echristley@nc.rr.com
Subject: AeroElectric-List: Motorcycle generators
--> AeroElectric-List message posted by: echristley@nc.rr.com
Background: I've been looking at motorcycle
generators as an easy way to push electrons around
an airplane. These things are basically a bunch of
coil on a ring that is mounted to the body, with a
shaft mounted "cup of magnets" that spins around the
coils.
Interesting part: One of the sites describing the
regulator said that it was basically a big resistor.
The generator always produced the same Watts of
energy (dependant upon engine RPM), but any that
aren't needed by the system are just converted to
heat through the regulator. The generator is self
limiting as long as it isn't overspeed. The magnets
are only so strong, so it isn't capable of
generating enough current to damage itself. This
differs from the alternator where the magnets are
replaced with a field coil that can basically create
a magnet capable of destroying the unit.
Small questions: When we talk about the PM
generators/alternators like those sold by B&C, is it
the same basic technology (ring of coils in a can of
magnets)?
Is the same type of dump-excess-to-ground regulator
used?
The Big Question: If you install one of the PM
electron pushers, would it not make sense to set its
voltage higher than any alternator? That is, make
it direct all of it's energy into useful work before
an alternator kicks in.
Message 14
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| Subject: | ELT Control Access |
--> AeroElectric-List message posted by: <bakerocb@cox.net>
AeroElectric-List message previously posted by: "Robert L. Nuckolls,
III"
<<11/11/2004
>Hello Bob Nuckolls, Thanks for the offer -- that was the object of my
>original request. I am led to believe that the ELT access requirement
>would be found in DO-182, DO-183, or DO-204. Thanks for your help.
>OC
I just found out that the documents you want are not
available for downloading (which means they're generally
free to members). I would have to order paper copies
at the member prices which I can do for you if you wish.
We might have them in a library somewhere on the square-mile.
I'll see if I can find them. Bob>>
11/16/2004
Hello Again Bob Nuckolls, and thanks for your generous offer. Let's drop it for
now-- you have enough on your plate.
I am pretty much convinced that people who have seen the documents have concluded
that the remote control and visual indication of activation of TSO-C91a ELT's
from the cockpit is a regulatory requirement by reference.
Philosophically I am irritated that the US Government uses our tax dollars to publish
a Federal Aviation Regulation that we are to abide by, uses the TSO system
to put teeth into that Regulation, and then says "By the way, if you really
want to know how and why to comply with this Regulation then you must go to
an independent private organization, the RTCA, and pay them money to get that
information."
OC
Message 15
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| Subject: | Re: Master Switch Question |
--> AeroElectric-List message posted by: "Tinne maha" <tinnemaha@hotmail.com>
What is the advantage of running the alternator field wire (main bus to
pullable breaker to 6 on LR3C) through a double pole switch? Wouldn't it
be equivalent to use a 1-3 switch for the battery master pull the breaker
for the few times you want to go battery only?
If you do as you've suggested, opening the Battery Master switch only
with the engine running will not make the system shut down. The alternator
will probably continue to run self-excited but with unpredictable
performance.
 
; This is why the alternator/battery switch were combined into their current
single two-pole switch configuration when generators (separate battery and
generator switches) were taken off the airplane. In the Z-figures, when
you turn the DC PWR MASTER switch OFF, the system goes completely dark
at operation of the one switch and without risk of leaving an alternator
on line after the battery is taken off.
Bob . . .
Other than alternator failure, when would one want to open the master switch with
the engine running?
Grant
Message 16
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| Subject: | Re: Motorcycle generators |
--> AeroElectric-List message posted by: Ernest Christley <echristley@nc.rr.com>
Trampas wrote:
> --> AeroElectric-List message posted by: "Trampas" <tstern@nc.rr.com>
>
> All PM generators are about the same, most regulators are shunt regulators
> like you described.
>
> The problem with PM generators is that they do not output enough voltage to
> charge battery till RPMs are relatively high.
>
> Regards,
> Trampas
>
A problem in a car, but you don't tend to idle much in an airplane 8*)
Where I'm thinking of sticking it on my rotary engine, it will spin at
around 5800 RPM in cruise flight. I will probably have two large
batteries in the tail for ballast depending on how light I can keep the
the nose. Running off the battery for an hour of taxiing probably won't
matter.
But that's all beside the point really. Several people are using the PM
generators as backup devices. My question is really, doesn't it make
more sense to use them as primary devices. An alternator stops pushing
on electrons when it's not necessary. Generators go right on shoving,
and drops the extra energy by stressing the shunt regulator. My
reasoning is that it would make more sense to take advantage of that
work the generator is doing, and only bring the alternator online when
necessary.
--
http://www.ernest.isa-geek.org/
"This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."
Message 17
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| Subject: | Re: Re: Keep warm circuit for Landing/Taxi |
lights
--> AeroElectric-List message posted by: "Richard E. Tasker" <retasker@optonline.net>
lights
Okay, this is a little better, but I still don't understand why you
think the transistors are better?
Even with the lower voltage drop they will still be wasting at least
three times as much power (1.125V*6A = 6.75W vs 2.2W). Yes, you can
(should) heat sink the transistors to keep them cool, but the thermistor
is supposed to run hot so just mount it somewhere you aren't going to
touch it and it is fine.
You state below that the steady state dissipation of the transistors is
about 1W. How the heck did you get that number??? My calculations show
about 2.25W per transistor if you use three to pass 6A.
Don't get me wrong, I am an EE and definitely believe in the "silicon
solutions" for airplane controls, etc., but I just can't see how three
transistors on a heat sink is easier or better than a simple thermistor.
Dick Tasker
Eric M. Jones wrote:
>--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>
>--> AeroElectric-List message posted by: "Richard E. Tasker"
><retasker@optonline.net>
>
>
>
>>>What am I missing here???
>>>
>>>
>
>You are missing the fact that I pushed the send button too early and lived
>to regret it. The 2V is saturation voltage not Vdrop across the thing. My
>fault. And it was past my bed-time. And I've been breathing fumes.
>
>Thermistors are great but they get their low resistance only when very hot.
>For a Keystone CL-10 with a 75W lamp (let's say 6A steady state). R=XI
>Y
>where X=0.50; I= 6; Y= -1.18 R=0.06. So W=36 x 0.06=2.2W. And that makes the
>nickel-sized part very hot with no hope of cooling it off.
>
>Why use the LM395T? The LM395T has a Vbe voltage of 1.125 V at 2A (current
>limit) and decreases below its current limit. (e.g. 0.90V at 1.2A). So we
>have a couple watts for a second when the lamp is first turned on, then
>about 1W dissipation when the lamp is on steady. Since these operate in
>parallel, it's a pretty good way to limit the lamp current at start-up. For
>a 75W lamp, use three. These would dissipate about as much as the
>thermistor, but you can cool them off! Digikey wants $3.38 each but my guess
>is that they can be gotten for a buck each if you search around. I think it
>is true to say that there is no lower-loss method of linear current
>limiting. And using them is at least as simple as using thermistors.
>
>
>Regards,
>Eric M. Jones
>www.PerihelionDesign.com
>113 Brentwood Drive
>Southbridge MA 01550-2705
>Phone (508) 764-2072
>Email: emjones@charter.net
>
>
Message 18
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| Subject: | Re: Master Switch Question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 07:39 PM 11/16/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "Tinne maha" <tinnemaha@hotmail.com>
>
>
> What is the advantage of running the alternator field wire (main bus to
> pullable breaker to 6 on LR3C) through a double pole switch? Wouldn't it
> be equivalent to use a 1-3 switch for the battery master pull the breaker
> for the few times you want to go battery only?
>
> If you do as you've suggested, opening the Battery Master switch only
> with the engine running will not make the system shut down. The alternator
> will probably continue to run self-excited but with unpredictable
> performance.
> 
> ; This is why the alternator/battery switch were combined into their current
> single two-pole switch configuration when generators (separate battery and
> generator switches) were taken off the airplane. In the Z-figures, when
> you turn the DC PWR MASTER switch OFF, the system goes completely dark
> at operation of the one switch and without risk of leaving an alternator
> on line after the battery is taken off.
>
>
> Bob . . .
>
>
>Other than alternator failure, when would one want to open the master
>switch with the engine running?
Smoke in cockpit, malfunctioning regulator (unstable or badly out
of calibration). Further, there's another FAR that has broad appeal
for both Spam Cans and OBAM aircraft: There needs to be pilot operated
controls that will shut down all sources of electrical power at any
time.
Bob . . .
Message 19
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| Subject: | Re: Welding Cable |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 04:11 PM 11/16/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: Jerry2DT@aol.com
>
>
>Bob and all..
>
>I bought some welding cable, was going to use it until I snipped a small
>piece and dipped it in gasoline for an hour. Gas pretty much melted the
>insulation, so wondering what other hydrocarbons like engine oil might
>also do...
>Comments?
Like ALL forms of wire, they can be acquired with a variety
of insulations. If you're suspicious, curious, skeptical of
the material purchased from bulk spool of local supplier,
then testing as you've described isn't a bad idea . . .
The cable we sold from here was locally purchased and tested
fine in gasoline. Get a the brand name and style off the spool
and look it up on the 'net.
A Google search of "welding cable oil resist" produced
over 18,000 hits. A few are shown below. I suspect
you're more likely to find good quality cable in a local
welding supply store than cheesy cable.
http://store.weldingdepot.com/cgi/weldingdepot/0004x.html
http://www.cvalim.co.il/products/flexible.asp
http://trailer-bodybuilders.com/mag/trucks_battery_welding_cable/
>Also, when you say "Battery jumper", what does this term refer to? Thanx...
The wires that run from battery(+) to contactor and battery(-) to
ground are the battery jumpers. It's a good idea to relieve potential
stresses on battery terminals as much as possible. 2AWG Tefzel
wire is NOT very conducive to stress relief. Even if the rest
of the airplane is wired with Tefzel, I'd use #4 welding cable for
the battery jumpers as both stress relief and user friendly when
it comes to attaching wires to the battery.
I used to offer custom bonding jumpers and battery jumpers or leads.
B&C still does. See
http://bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?26X358218
Bob . . .
Message 20
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| Subject: | Re: DC motor braking diagram |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 02:59 PM 11/16/2004 -0600, you wrote:
>--> AeroElectric-List message posted by: "James Redmon" <james@berkut13.com>
>
>Can someone point me to the circuit diagram (or provide it) that shows how
>to hook-up a trim switch and polarity reversing relay deck to a DC motor
>such that the motor's power leads are connected together to provide motor
>braking - at least I think that was how it went. I remember seeing it
>somewhere, can't remember if I saw it in the "connection" or elsewhere. I
>think the example was a flap extension hook-up I saw.
>
>My hangarmate borrowed my electrical bible...(sigh)
See http://www.aeroelectric.com/PPS/Flight/Flaps
There are several variations on a theme posted there.
Bob . . .
Message 21
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| Subject: | Re: DC motor braking diagram |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 02:59 PM 11/16/2004 -0600, you wrote:
>--> AeroElectric-List message posted by: "James Redmon" <james@berkut13.com>
>
>Can someone point me to the circuit diagram (or provide it) that shows how
>to hook-up a trim switch and polarity reversing relay deck to a DC motor
>such that the motor's power leads are connected together to provide motor
>braking - at least I think that was how it went. I remember seeing it
>somewhere, can't remember if I saw it in the "connection" or elsewhere. I
>think the example was a flap extension hook-up I saw.
>
>My hangarmate borrowed my electrical bible...(sigh)
Oops, that was flaps, here's Trim . . .
See http://www.aeroelectric.com/PPS/Flight/Trim
There are several variations on a theme posted there.
Bob . . .
Message 22
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| Subject: | Re: ELT Control Access - OT |
--> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch>
>Philosophically I am irritated that the US Government uses our tax dollars to
publish a Federal Aviation Regulation that we are to abide by, uses the TSO system
to put teeth into that Regulation, and then says "By the way, if you really
want to know how and why to comply with this Regulation then you must go to
an independent private organization, the RTCA, and pay them money to get that
information."
I totally agree. I think when people talk about privatizing
certain government functions they don't want a private company
handed a sweetheart deal so that they can become a monopoly.
If it can be done by the private sector, with real competition,
then great. Otherwise, we have to find another solution.
--
Mickey Coggins
http://www.rv8.ch/
#82007 QB Wings/Fuselage
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