Today's Message Index:
----------------------
1. 10:28 AM - Re: Strobe Supply maintenance (Robert L. Nuckolls, III)
2. 10:29 AM - Re: battery cable size (Robert L. Nuckolls, III)
3. 10:43 AM - Re: Re: battery cable size (Jim Stone)
4. 10:48 AM - Re: Fan generating power?? (Robert L. Nuckolls, III)
5. 10:51 AM - Re: Power supplies (Robert L. Nuckolls, III)
6. 10:59 AM - Shielded sensor wires (Terry Watson)
7. 11:31 AM - Re: Re: battery cable size (Robert L. Nuckolls, III)
8. 11:43 AM - Re: Re: battery cable size (David Swartzendruber)
9. 01:27 PM - Re: Shielded sensor wires (Robert L. Nuckolls, III)
10. 01:44 PM - Kalamazoo MI Seminar date set (Robert L. Nuckolls, III)
11. 01:58 PM - Re: Current leak, revisited (Robert L. Nuckolls, III)
12. 02:01 PM - Re: Seat Heater Question (Robert L. Nuckolls, III)
13. 02:04 PM - Re: Alternator exchange (Robert L. Nuckolls, III)
14. 02:37 PM - Re: Seat Heater Question (Larry Bowen)
15. 04:07 PM - Re: Fan generating power?? (Jon Finley)
16. 04:16 PM - Low Voltage/OV Warning current from bus to regulator...fuse or breaker? (Ralph E. Capen)
17. 04:51 PM - Re: Fan generating power?? (Matt Prather)
18. 05:17 PM - Re: Fan generating power?? (Robert L. Nuckolls, III)
19. 05:23 PM - Re: Seat Heater Question (Robert L. Nuckolls, III)
20. 05:34 PM - Re: Fan generating power?? (Robert L. Nuckolls, III)
21. 05:58 PM - Turn and slip voltage? (richard@riley.net)
22. 06:05 PM - Re: KT-76A Pinout Clarification (Robert L. Nuckolls, III)
23. 07:25 PM - Re: Fan generating power?? (Jon Finley)
Message 1
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| Subject: | Re: Strobe Supply maintenance |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 04:38 PM 1/25/2004 +0000, you wrote:
>Below is the result of your inquiry. It was submitted by
>JIM SHERRY (jamesmdsherry@aol.com) on Sunday, January 25, 2004 at 08:38:51
>
>Sunday, January 25, 2004
>
>JIM SHERRY
>
>,
>Email: jamesmdsherry@aol.com
>Comments/Questions: Hi , I did an EAA aircraft wiring course in Denver
>with Marty Elshire. Marty and the course were outstanding! Would you be
>able to give Marty a comment? The power supply for Aero Lighting, that is
>sold through Cleavland Tool Co. (about last page in catoluge) does need to
>be recharged every 6 months. During class Marty did not think the power
>supply would bneed a recharge at all and could sit on a shelf until
>installed. Thanks, Jim Sherry ( just finishing right wing)
This technique of rejuvenating an strobe power supply
that has stood idle for long periods of time has some
valid roots in the component antiquity. Aluminum electrolytic
capacitors are fabricated from thin layers of aluminum
foil with a witch's brew of chemicals separating the
two foils. During manufacturing, a voltage is applied
to the capacitor causing the aluminum to react with
the chemistry to form the (+) and (-) plates of
capacitor.
40 years ago, it was not uncommon for a "new" capacitor
stored for years on the shelf to exhibit a rise in
leakage current and a reduction in effective capacity.
Near fresh performance could be restored by what is
sometimes called a "voltage treatment" . . . charging
and holding a capacitor at its rated operating voltage
will limiting the charging current with a 1K resistor.
If the capacitor is already installed, a similar treatment
can be implemented by slowly raising the supply voltage
to the system.
Aluminum capacitor theory, practice and usage is very
nicely described in this document:
http://www.nichicon-us.com/english/lib/alminium.pdf
Check out page 18, paragraph 2.6 where the author
describes this phenomenon and activity with a description
of the remedy. Take a look at the bottom graph in
figure 2-10 were leakage current with age is plotted.
That's a logarithmic scale . . . the typical current rise
over a 3 year storage was from 10 to 20 uA. Hmmm . . .
that's not much current.
Being a firm believer in value of the repeatable
experiment, I dug around in the junk box and found
a 1000 uF/350V capacitor with a date code of June
1995. I salvaged these from a power supply well over
two years ago so I know they've been sitting on
my shelf at least two years.
I put 300v across this capacitor and measured
leakage current. After the initial charging surge,
leakage was in the 5 milliampere range. In less
than 2 minutes it had fallen to 1 milliampere.
After 10 minutes it was about 50 microamperes.
This capacitor is about twice the size of that
used in a 20 joule/flash power supply so I would
expect leakage currents measured above to be
higher than those in an exemplar flash capacitor.
These values of leakage represent very small,
stresses of short duration upon the capacitors
or any other components in the system.
Yes, the capacitor manufacturers speak of this
phenomenon in their engineering literature as
well they should. But other engineers should
take that data, compare with real-world effects
and craft maintenance policy based upon value-
added for having made the effort.
Bottom line is that some folks have taken a
few facts about leakage and ageing of capacitors
and spun them into a policy and procedure for
strobe supplies that has no practical value.
It sure makes good worry-fodder.
Unless you've salvaged a strobe system out
of an airplane that was manufactured 20+ years
ago, I'd 'worry' more about getting the right
bolts to attach your prop and the right
architecture for your airplane that will insure
sweat-free flying.
I will invite you to join us on the AeroElectric List
to continue this and similar discussions. It's
useful to share information with as may folks as
possible. You can join at:
http://www.matronics.com/subscribe/
Thanks!
Bob . . .
Message 2
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| Subject: | Re: battery cable size |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 04:33 PM 1/25/2004 +0000, you wrote:
>Below is the result of your inquiry. It was submitted by
>Lytle Johnson (catrax@rockisland.com) on Sunday, January 25, 2004 at 08:33:31
>
>Sunday, January 25, 2004
>
>Lytle Johnson
>
>,
>Email: catrax@rockisland.com
>Comments/Questions: Just got your book in the mail. Thank you. (Decatur
>Island). Haven't been able to find a simple answer to Is 4AWG cable ok
>when I'm running ~15 ft (30' round trip) from Odyssey 680 (RG, I think) to
>starter, SuperCub type homebuilt, 180 hp Lycoming?
>I'm running a parallel ground cable to the front for a single-point ground
>system, and all accessories carry their grounds back to common instead of
>relying on airframe.
>Sure would like to avoid weight of 2AWG but want to do the right thing.
4AWG is too small for that long a run. I recommend
2AWG. Look into the use of welding cable.
I will invite you to join us on the AeroElectric List
to continue this and similar discussions. It's useful to
share the information with as many folks as possible.
A further benefit can be realized with membership on
the list. There are lots of technically capable folks
on the list who can offer suggestions too. You can
join at . . .
http://www.matronics.com/subscribe/
Thanks!
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
Message 3
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| Subject: | Re: battery cable size |
--> AeroElectric-List message posted by: "Jim Stone" <jrstone@insightbb.com>
Bob,
Do you know of a good source for welding cable (2 and 4awg)?
Jim
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L. Nuckolls, III
Subject: AeroElectric-List: Re: battery cable size
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
At 04:33 PM 1/25/2004 +0000, you wrote:
>Below is the result of your inquiry. It was submitted by
>Lytle Johnson (catrax@rockisland.com) on Sunday, January 25, 2004 at
08:33:31
>
>Sunday, January 25, 2004
>
>Lytle Johnson
>
>,
>Email: catrax@rockisland.com
>Comments/Questions: Just got your book in the mail. Thank you. (Decatur
>Island). Haven't been able to find a simple answer to Is 4AWG cable ok
>when I'm running ~15 ft (30' round trip) from Odyssey 680 (RG, I think)
to
>starter, SuperCub type homebuilt, 180 hp Lycoming?
>I'm running a parallel ground cable to the front for a single-point
ground
>system, and all accessories carry their grounds back to common instead
of
>relying on airframe.
>Sure would like to avoid weight of 2AWG but want to do the right thing.
4AWG is too small for that long a run. I recommend
2AWG. Look into the use of welding cable.
I will invite you to join us on the AeroElectric List
to continue this and similar discussions. It's useful to
share the information with as many folks as possible.
A further benefit can be realized with membership on
the list. There are lots of technically capable folks
on the list who can offer suggestions too. You can
join at . . .
http://www.matronics.com/subscribe/
Thanks!
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
==
==
==
==
Message 4
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| Subject: | Re: Fan generating power?? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:50 PM 1/24/2004 -0600, you wrote:
>--> AeroElectric-List message posted by: "Jon Finley" <jon@finleyweb.net>
>
>Hi all,
>
>I was recently having a discussion with someone regarding the addition
>of an automotive radiator fan to my cooling system. This person warned
>me that these fans can produce power when free-wheeling (spinning from
>the air blowing thru them). Is there anything to this or just another
>old wives tale?? If there is, how does one "solve" this (ground both
>positive and negative fan wires when fan is off??)?
>
>Thanks!
If the motor is permanent magnet or brushless dc, it WILL
generate some voltage when the motor is spun by ambient
breezes through the fan blade . . . but so what? If your
power switch is OFF, the voltage simply appears as a potential
source of energy with no place to go. If the voltage is
higher than bus voltage, this says that the breezes are
rotating the fan at more than design speed for blower.
This DOES warrant the question about whether or not the
blade is at risk or brushes are wearing out even when
the fan isn't needed.
We had a brushless design for the condenser blower
on a big turboprop that would spin a greater than
design speed at cruise. We had to put in a load bank
to turn that potential energy into heat and slow the
motor down to more reasonable speeds.
It's doubtful that you're going to find this kind
of problem but it's worth investigating. Put a voltmeter
on the motor and see what it reads when the motor is
turned OFF and you're in a cruise condition.
90+% probability that there's nothing to be "solved".
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 5
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| Subject: | Re: Power supplies |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:47 PM 1/24/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: "Bob (Rocketboy)"
><f1rocketboy@bellsouth.net>
>
>This is kinda like spam (sorry), but entertaining none the less for you guys
>doing power supplies to run all those computerized avionics.
>
>http://www.f1-rocketboy.com/power.htm
Kinda cute . . . BUT. These power supplies are plentiful
and efficient and cheap . . . but they're set up for computer
service at 12.0 volts nominal. You can certainly use them
to run things in the airplane but if your battery is on line
too, it won't charge the battery . . . in fact, the battery
will deliver energy into the system too and become slightly
discharge.
Look for bench supplies in the 13.8 volt range . . . these
are INTENDED to drive automotive products and charge batteries
in a 14V vehicular system.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 6
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| Subject: | Shielded sensor wires |
--> AeroElectric-List message posted by: "Terry Watson" <terry@tcwatson.com>
Bob or anyone else who knows,
Both the thermocouple EGT wires for my and the wires for my CHT (resistance)
are covered with a woven metal sheathing. (8 total pairs of shielded wire).
It would be most convenient to run all the engine sensor wires in a bundle
within an inch or so of the back of the radio stack. Is that a problem?
Second question: Is the shielding necessary? It would be most convenient
to go to unshielded 22 ga wire for all of these once on the cockpit side of
the firewall. I could run all the sensor wires in a bundle through a big
woven stainless sleeve (Boeing surplus) if that made any difference.
Thanks!
Terry Watson
RV-8A with Blue Mountain EFIS/one
Seattle
Message 7
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| Subject: | Re: battery cable size |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 01:42 PM 1/25/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: "Jim Stone" <jrstone@insightbb.com>
>
>Bob,
>Do you know of a good source for welding cable (2 and 4awg)?
>Jim
Welding supplies store . . . check your yellow pages.
Bob . . .
Message 8
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| Subject: | Re: battery cable size |
--> AeroElectric-List message posted by: "David Swartzendruber" <dswartzendruber@earthlink.net>
If you can't find any locally, I've got 2ga. on hand in red and black.
Terminals and crimping available as well.
Dave
> >
> >Bob,
> >Do you know of a good source for welding cable (2 and 4awg)?
> >Jim
>
> Welding supplies store . . . check your yellow pages.
>
> Bob . . .
>
>
Message 9
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| Subject: | Re: Shielded sensor wires |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 10:58 AM 1/25/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "Terry Watson" <terry@tcwatson.com>
>
>Bob or anyone else who knows,
>
>Both the thermocouple EGT wires for my and the wires for my CHT (resistance)
>are covered with a woven metal sheathing. (8 total pairs of shielded wire).
>It would be most convenient to run all the engine sensor wires in a bundle
>within an inch or so of the back of the radio stack. Is that a problem?
Shouldn't be . . .
>Second question: Is the shielding necessary? It would be most convenient
>to go to unshielded 22 ga wire for all of these once on the cockpit side of
>the firewall. I could run all the sensor wires in a bundle through a big
>woven stainless sleeve (Boeing surplus) if that made any difference.
If you're extending thermocouple wires, you need to use the
same style of thermocouple material for extending them. All
of those sensors are low impedance devices and are neither
antagonistic to other systems or much of a potential victim.
I'm mystified as to why they would be offered as shielded.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 10
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| Subject: | Kalamazoo MI Seminar date set |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Got the word from folks in Kalamazoo finalizing preparations
for a seminar on March 20/21. It will be held in Duncan
Aviation's facility on the airport. See:
http://www.aeroelectric.com/seminars/Kalamazoo.html
for details.
I would appreciate it if subscribers to other lists
on Matronics would forward this message to those
lists.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 11
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| Subject: | Re: Current leak, revisited |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:37 PM 1/23/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "hollandm" <hollandm@pacbell.net>
>
>Per Bob's direction I charged my system by turning on the master. With
>the master off the residual voltage was about 0.6volts. When I hooked the
>meter into the same side of the circuit to measure current I could not
>detect any measurable current at a sensitivity of 0.001 amps.
>
>I have no capacitors installed, anywhere, at this stage, no engine and
>just wiring switches and busses at the moment.
>
>The diode in the current path is the steering diode and is wired between
>the main and ebus, per Z13.
>
>I think Eric Jones is on the right track, but in the absence of any
>capacitors, how about this theory. Could the metal fuselage itself act as
>sort of a capacitor, if that possible? Whatever induces the voltage has
>a current is less than 1 milliamp and takes many hours to discharge.
The e-bus normal feed diode doesn't have any voltage across it unless the
battery master or e-bus alternate feed switches are closed. The meter
you're using has a VERY high input impedance . . . usually 10 megohms.
This means that "leakage" needed to make it indicate .6 volts is
on the order of 60 nanoamps. You can get that kind of current flow
by shuffling your feed on the carpet. I'm surprised that you don't
have some kind of always-on load that would pull the reading on down
to zero with all the switches open.
In any case, nothing to be concerned about.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 12
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| Subject: | Re: Seat Heater Question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:04 AM 1/24/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: Charlie Kuss <chaskuss@bellsouth.net>
>
>Randy,
> I'd suggest that you wire the low power (trigger) ignition lead from the
> main buss. The intent is that you can't activate the circuit if the
> ignition (master relay in our case) is off. This is so you don't run down
> your battery accidently
>Charlie Kuss
>
> >--> AeroElectric-List message posted by: F1Rocket@comcast.net
> >
> >I recently bought a set of automobile electrical seat heaters for my F1
> Rocket. The wiring diagram shows a 10A power lead from the bus to the
> relay, and a low current wire from the ignition to the relay. In an
> aircraft application, I don't see the need for the ignition side of
> this. I'm thinking that I can just connect both the power lead and the
> ignition lead to the wire from the bus.
10A is the protection size . . . what's the REAL
current? In any case, consider mounting your relays
at the battery bus and put 10A fuses on the bus to
power the heaters. Operate the relay controls through
switches that get power from the main bus so that
they power down during parked and alternator-out operations.
Bob . . .
Message 13
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| Subject: | Re: Alternator exchange |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:10 AM 1/23/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: "Dean Psiropoulos"
><deanpsir@easystreet.com>
>
>Lectric Bob:
>
>
>Given all the discussion about OV protection, I have always intended to
>install that kind of insurance on my airplane. I'm finally down to
>finishing and bought a firewall forward kit from Van's aircraft. It
>contains a rebuilt Nippon Denso alternator (60 amp) but unfortunately that
>unit is internally regulated.
Wire Figure Z-24
> I think this is the same unit that B&C
>modifies and sells.
similar . . .
> My question is: if I send this unit over to B&C can
>they modify it for a reasonable fee?
probably but it might take a LONG time . . . I'd
use the one you have.
> Or maybe I can exchange it and a few
>bucks for a B&C alternator that I can use with your OV protection. Or
>should I just use it as is because the probability of an OV failure is very
>small and therefore not worth the extra money need to modify the unit I
>already have?
Nope, it's easy to add ov protection to the alternator you
have.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 14
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| Subject: | Seat Heater Question |
--> AeroElectric-List message posted by: "Larry Bowen" <Larry@BowenAero.com>
My seat heater documentation call for a 10A fuse too. About 6A is the
max I've seen, just as they are turned on. That's 6A per seat, both
butt and back heaters.
-
Larry Bowen
Larry@BowenAero.com
http://BowenAero.com
> -----Original Message-----
> From: Robert L. Nuckolls, III [mailto:bob.nuckolls@cox.net]
> Sent: Sunday, January 25, 2004 5:01 PM
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Seat Heater Question
>
>
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> --> <bob.nuckolls@cox.net>
>
> 10A is the protection size . . . what's the REAL
> current? In any case, consider mounting your relays
> at the battery bus and put 10A fuses on the bus to
> power the heaters. Operate the relay controls through
> switches that get power from the main bus so that
> they power down during parked and alternator-out operations.
>
> Bob . . .
Message 15
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| Subject: | Fan generating power?? |
--> AeroElectric-List message posted by: "Jon Finley" <jon@finleyweb.net>
Well, since the fan positive connection hooks directly into the EFI
computer, the "story" goes on to say that odd EFI problems would pop up.
So, the "so what?" is an "occasionally" poor running engine that is
nearly impossible to diagnose (per the "story").
Since nobody has heard of this problem, I will assume it is just an old
wives tale and find something else to worry about. :-)
Thanks all,
Jon Finley
N90MG Q2 - Subaru EJ-22 DD - 461 Hrs. TT
Apple Valley, Minnesota
http://www.FinleyWeb.net/Q2Subaru
> >--> AeroElectric-List message posted by: "Jon Finley"
> >--> <jon@finleyweb.net>
> >
> >Hi all,
> >
> >I was recently having a discussion with someone regarding
> the addition
> >of an automotive radiator fan to my cooling system. This
> person warned
> >me that these fans can produce power when free-wheeling
> (spinning from
> >the air blowing thru them). Is there anything to this or
> just another
> >old wives tale?? If there is, how does one "solve" this
> (ground both
> >positive and negative fan wires when fan is off??)?
> >
> >Thanks!
>
> If the motor is permanent magnet or brushless dc, it WILL
> generate some voltage when the motor is spun by ambient
> breezes through the fan blade . . . but so what? If your
> power switch is OFF, the voltage simply appears as a potential
> source of energy with no place to go. If the voltage is
> higher than bus voltage, this says that the breezes are
> rotating the fan at more than design speed for blower.
> This DOES warrant the question about whether or not the
> blade is at risk or brushes are wearing out even when
> the fan isn't needed.
>
> We had a brushless design for the condenser blower
> on a big turboprop that would spin a greater than
> design speed at cruise. We had to put in a load bank
> to turn that potential energy into heat and slow the
> motor down to more reasonable speeds.
>
> It's doubtful that you're going to find this kind
> of problem but it's worth investigating. Put a voltmeter
> on the motor and see what it reads when the motor is
> turned OFF and you're in a cruise condition.
>
> 90+% probability that there's nothing to be "solved".
>
> Bob . . .
Message 16
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| Subject: | Low Voltage/OV Warning current from bus to regulator...fuse |
or breaker?
--> AeroElectric-List message posted by: "Ralph E. Capen" <recapen@earthlink.net>
Folks - here's a recent exchange that I'm posting for archival purposes.
The list is great too...!
Ralph Capen
----- Original Message -----
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: Re: E-mail Contact Request
>
> >
> > > Low Voltage/OV Warning current from bus to regulator...fuse or
breaker?
> > >
> > > Should have looked further before I ordered...some of your figures
show a
> >fuse and others show a breaker. I just ordered a pair of 2A breakers
(from
> >this site...) for my RV6A that I am setting up per Z12 which shows 2A
> >breakers. On further examination, Z13, Z14, Z15 shows fuses of differing
> >ratings while Z11 shows a 5A breaker. Doesn't matter to me - now that I
> >have already ordered the breakers except they may not be the correct
current
> >rating and I have ordered plenty of fuses.
>
>
> The wire between the bus and pins 3/5 of the LR3
> regulator can be protected at any level from 1A
> (more than current draw) up to 5A (appropriate to
> 22AWG wire). You can use either breakers or fuses
> depending on what bus and protection style you've
> chosen to use. The Field supply to pin 6 should
> ALWAYS get a 5A breaker either right on the bus
> if your bus structure uses breakers or at some
> point downstream of a fusible link if you're using
> fuseblocks.
>
> I will invite you to join us on the AeroElectric List
> to continue this and similar discussions. It's useful to
> share the information with as many folks as possible.
> A further benefit can be realized with membership on
> the list. There are lots of technically capable folks
> on the list who can offer suggestions too. You can
> join at . . .
>
> http://www.matronics.com/subscribe/
>
> Thanks!
>
> Bob . . .
>
> --------------------------------------------
> ( Knowing about a thing is different than )
> ( understanding it. One can know a lot )
> ( and still understand nothing. )
> ( C.F. Kettering )
> --------------------------------------------
>
>
Message 17
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| Subject: | Fan generating power?? |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
It seems sort of hard to imagine that the fan would be powered
directly from the computer. Seems like you would need a relay
to handle the current demands of the fan. The relay would
provide isolation for the computer from the voltage generated
by the freewheeling fan. I guess maybe the computer could be monitoring
the voltage on the fan as a means of sensing airflow through the radiator
(since the fan probably free wheels in the automotive application), but it
seems unlikely, That would likely
be a documented feature, if it existed.
Regards,
Matt-
N34RD
> --> AeroElectric-List message posted by: "Jon Finley"
> <jon@finleyweb.net>
>
> Well, since the fan positive connection hooks directly into the EFI
> computer, the "story" goes on to say that odd EFI problems would pop up.
> So, the "so what?" is an "occasionally" poor running engine that is
> nearly impossible to diagnose (per the "story").
>
> Since nobody has heard of this problem, I will assume it is just an old
> wives tale and find something else to worry about. :-)
>
> Thanks all,
>
> Jon Finley
> N90MG Q2 - Subaru EJ-22 DD - 461 Hrs. TT
> Apple Valley, Minnesota
> http://www.FinleyWeb.net/Q2Subaru
>
>> >--> AeroElectric-List message posted by: "Jon Finley"
>> >--> <jon@finleyweb.net>
>> >
>> >Hi all,
>> >
>> >I was recently having a discussion with someone regarding
>> the addition
>> >of an automotive radiator fan to my cooling system. This
>> person warned
>> >me that these fans can produce power when free-wheeling
>> (spinning from
>> >the air blowing thru them). Is there anything to this or
>> just another
>> >old wives tale?? If there is, how does one "solve" this
>> (ground both
>> >positive and negative fan wires when fan is off??)?
>> >
>> >Thanks!
>>
>> If the motor is permanent magnet or brushless dc, it WILL
>> generate some voltage when the motor is spun by ambient
>> breezes through the fan blade . . . but so what? If your
>> power switch is OFF, the voltage simply appears as a potential
>> source of energy with no place to go. If the voltage is
>> higher than bus voltage, this says that the breezes are
>> rotating the fan at more than design speed for blower.
>> This DOES warrant the question about whether or not the
>> blade is at risk or brushes are wearing out even when
>> the fan isn't needed.
>>
>> We had a brushless design for the condenser blower
>> on a big turboprop that would spin a greater than
>> design speed at cruise. We had to put in a load bank
>> to turn that potential energy into heat and slow the
>> motor down to more reasonable speeds.
>>
>> It's doubtful that you're going to find this kind
>> of problem but it's worth investigating. Put a voltmeter
>> on the motor and see what it reads when the motor is
>> turned OFF and you're in a cruise condition.
>>
>> 90+% probability that there's nothing to be "solved".
>>
>> Bob . . .
>
>
Message 18
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| Subject: | Fan generating power?? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 06:06 PM 1/25/2004 -0600, you wrote:
>--> AeroElectric-List message posted by: "Jon Finley" <jon@finleyweb.net>
>
>Well, since the fan positive connection hooks directly into the EFI
>computer, the "story" goes on to say that odd EFI problems would pop up.
>So, the "so what?" is an "occasionally" poor running engine that is
>nearly impossible to diagnose (per the "story").
>
>Since nobody has heard of this problem, I will assume it is just an old
>wives tale and find something else to worry about. :-)
Aha! Not all of the data was out on the table. If this
fan is driven by electronics inside some black box, then
it is important to know the details of how it happens. I
would presume that the black box contains a relay or solid
state equivalent to control power to the fan. The black
box may also feature some kind of monitoring where voltage
downstream of the relay is expected to go away when the
command says "OFF". If air driven free-wheeling can cause
this signal to be in error, there is a question as to
how the black box regards this fact.
Something to consider for further investigation in
case you experience unexplained abnormal behavior.
Bob . . .
Message 19
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| Subject: | Seat Heater Question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 05:34 PM 1/25/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: "Larry Bowen" <Larry@BowenAero.com>
>
>My seat heater documentation call for a 10A fuse too. About 6A is the
>max I've seen, just as they are turned on. That's 6A per seat, both
>butt and back heaters.
Do you ever find it useful to run only one of the two heaters
in each seat? If so, which one?
If just one, then a 2-10 switch could be wired for
OFF-BUTT-BOTH or OFF-BACK-BOTH. Each seat could
be handled nicely from the main bus through the
switch and eliminate the relays entirely.
This would be true if the relays are used only to
control heaters via the panel switches. Are there
any thermostats in the seats to prevent overheating?
If so, they'll take advantage of the low coil current
in relays. If this is the case, then the relays
are needed.
We've heard it said that pictures are worth thousands
of words . . . I'll suggest that schematics are worth
a lot too. They really help you understand how the
thing really works.
Bob . . .
Message 20
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| Subject: | Fan generating power?? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 05:51 PM 1/25/2004 -0700, you wrote:
>--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
>
>It seems sort of hard to imagine that the fan would be powered
>directly from the computer. Seems like you would need a relay
>to handle the current demands of the fan. The relay would
>provide isolation for the computer from the voltage generated
>by the freewheeling fan. I guess maybe the computer could be monitoring
>the voltage on the fan as a means of sensing airflow through the radiator
>(since the fan probably free wheels in the automotive application), but it
>seems unlikely, That would likely be a documented feature, if it existed.
Gee Matt . . . "documented" . . . oh yes, this is an
automotive application. Probably a lot fewer surprises
on important matters than we see in airplanes.
It sure would be nice to see a schematic of the EFI.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 21
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| Subject: | Turn and slip voltage? |
--> AeroElectric-List message posted by: richard@riley.net
I have a small JET turn and slip indicator, it's marked ARU/54-A. A search
on the web shows it came from an AV-8B Harrier. It has a 6 pin connector.
Anyone have any idea what kind of voltage it wants?
Message 22
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| Subject: | Re: KT-76A Pinout Clarification |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 08:10 PM 1/22/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "John Wiegenstein"
><n727jw@hellerwiegenstein.com>
>
>OK, the KT-76A has shown up in the extensive (expensive?) Honeywell box.
>I've downloaded Bob's pinout PDF for this unit, but want to make sure its
>wired up correctly. The connector that came with the unit does not have a
>"one way" tab to prevent a reversed assembly, but the pin numbers and
>letters on the connector are as shown in Bob's pinout, and the edge
>connector on the unit has a slot near one end, such that the numbers and
>letters seem to match. But before I accidentally let all the smoke out of
>the insides, has anyone done a recent install and can confirm this?
First, if you have the KT76A, then I'm curious as to where
you got the pinout. Until a few minutes ago, only the KT76/78
drawing was posted the KT76A/76C/78A drawing at:
http://www.aeroelectric.com/Installation_Data/KT76A-76C-78A.pdf
This drawing shows the keyway plug being inserted between pins
3/4, C/D. This should get your plug lined up properly and confirm
that numbered pins are on the top surface of the ECB connector
sticking out through the hole in the case.
>Couple other questions: (1) What are the A1, A2, A4, B1, B2, B4, C1, C2,
>C4, and D4 circuits for? Encoder?
Yes. See:
http://www.aeroelectric.com/Installation_Data/T2000-ACK350_Wiring.pdf
for an exemplar wiring diagram for the Microair T2000 and an ACK350
encoder.
> (2) The "Ext Ident" and "Ext Stby"
>would appear to be for external/remote switching of these functions.
Correct.
> But what is "DME Suppression"???
Since DME and Transponders are very closely spaced in frequency,
there was need for a way to let each other know when they were
transmitting. This suppression signal keeps the transponder transmitter
from overloading the DME receiver and vice versa.
> (3)Is there a preferred way to test the
>connections and function to be sure everything's wired up right?
Wire carefully. Have someone help you ring out the wires
with buzzer from one connector to another, swap connectors
and repeat. This will find 99.99% of errors.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 23
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| Subject: | Fan generating power?? |
--> AeroElectric-List message posted by: "Jon Finley" <jon@finleyweb.net>
Your right Matt, I completely forgot about the relay. So, to clarify;
the ECU drives a relay which controls the fan. This relay makes the
story seem even less plausible.
As far as documentation goes: My current electrical system diagram is
at: http://www.finleyweb.net/default.asp?id=131 (no fan).
The stock Subaru EFI documentation is at:
http://www.finleyweb.net/default.asp?id=142 in the service manuals (1990
EJ-22 Legacy). Pages and pages of wiring... :-)
Jon Finley
N90MG Q2 - Subaru EJ-22 DD - 461 Hrs. TT
Apple Valley, Minnesota
http://www.FinleyWeb.net/Q2Subaru
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> --> <bob.nuckolls@cox.net>
>
> At 05:51 PM 1/25/2004 -0700, you wrote:
> >--> AeroElectric-List message posted by: "Matt Prather"
> >--> <mprather@spro.net>
> >
> >It seems sort of hard to imagine that the fan would be
> powered directly
> >from the computer. Seems like you would need a relay
> >to handle the current demands of the fan. The relay would
> >provide isolation for the computer from the voltage generated by the
> >freewheeling fan. I guess maybe the computer could be
> monitoring the
> >voltage on the fan as a means of sensing airflow through the
> radiator
> >(since the fan probably free wheels in the automotive
> application), but
> >it seems unlikely, That would likely be a documented feature, if it
> >existed.
>
> Gee Matt . . . "documented" . . . oh yes, this is an
> automotive application. Probably a lot fewer surprises
> on important matters than we see in airplanes.
>
> It sure would be nice to see a schematic of the EFI.
>
> Bob . . .
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