Today's Message Index:
----------------------
1. 07:08 AM - Re: Big load on BAT BUS (Robert L. Nuckolls, III)
2. 08:08 AM - Re: Re: Big load on BAT BUS (Robert L. Nuckolls, III)
3. 08:20 AM - Re: Surface temperature sensor (Robert L. Nuckolls, III)
4. 08:23 AM - Re: Big load on BAT BUS (Ken)
5. 08:27 AM - Re: Proper SWR meter (Robert L. Nuckolls, III)
6. 09:07 AM - Re: Big load on BAT BUS (jonlaury)
7. 11:18 AM - Re: Surface temperature sensor (J. Mcculley)
8. 12:10 PM - Re: Proper SWR meter (earl_schroeder@juno.com)
9. 02:45 PM - Re: Re: Designing a circuit question (Mike Welch)
10. 07:31 PM - Z-12 Power Grid Behavior (Valin & Allyson Thorn)
11. 07:31 PM - Re: Surface temperature sensor (Robert L. Nuckolls, III)
12. 07:36 PM - Re: Re: Big load on BAT BUS (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Big load on BAT BUS |
At 01:31 AM 4/24/2010, you wrote:
>
>In an attempt to keep redundant critical items from the same bus, I
>have placed the fuse (10-15 amp) for my EFI injectors on the Bat Bus.
>However, this violates BoB N's limit of
Then you need a "mini-contactor" at the battery
bus as illustrated in Z-32, except that the
feeder is for the EFI instead of the E-bus.
It would be nice if it were a solid state
relay. I believe Eric Jones still offers
on.
Bob . . .
Message 2
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Subject: | Re: Big load on BAT BUS |
At 01:38 AM 4/24/2010, you wrote:
>
>Never mind about the SS sleeve question. It will only be a 10 gauge
>wire and I will 18 ga fuselink it at the battery.
This sounds like another "loose cannon"
implementation of fusible links. Fusible
links are ROBUST circuit protection and should
never be used in an always-hot feeder from
a battery. If you've attached a wire to
a battery that calls for this kind of circuit
protection, it should enjoy upstream, crew-
controlled management of power.
As a general rule, please do not add fusible
links to any application not already illustrated
in the Z-figures without discussing it here
on the List . . . and I can tell you in advance
there's a 90+ percent chance that the proposed
application is not recommended.
Always-hot feeders should be breakered at
5A or less, fused at 7A or less. Anything
larger should still take a fuse or breaker
but CONTROLLED IMMEDIATELY ADJACENT to
the bus with a relay like that shown in Z-32.
Bob . . .
Message 3
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Subject: | Re: Surface temperature sensor |
At 09:38 PM 4/23/2010, you wrote:
>Mcculley" <mcculleyja@starpower.net>
>
>Sorry Steve and others...I just thought this subject might be of
>interest to so few that I should not take up
>bandwith that those not interested would have to deal with. But, here it is:
>
>
>This is a very accurate system that I tested with a laboratory quality
>temperature meter and found the accuracy of all my sensors to be two
>degrees F. It may not be very sophisticated, but it is super-inexpensive
>and has never malfunctioned. I use it on every flight to assure myself
>that no changes suddenly occur that could indicate a malfunction.
>
>Mine is about a $15 to $25 system that I've operated now for over seven
>years and upwards of 600 flight hours on it's original internal
>watch-size battery. The sensors are standard mini glass-encapsulated
>thermistors available from most electronic supply sources. I used
>Digi-Key # KC013-ND, 100k ohm units.
How was it that you determined that the 100K devices were
appropriate to your particular display? Folks should understand
that there are hundreds of remote temperature measurement
products on the market. I've see them use thermocouples, solid
state LINEAR temperature sensors, diodes, the junctions of
transistors (also a diode) AND thermistors.
http://www.gesensing.com/products/resources/datasheets/ge1.pdf
Thermistors are inexpensive AND rugged but they have the
distinct disadvantage of being non-linear. So the accurate
temperature display not only needs to know what the resistance
of the device is at say 25C, the designer will compensate for
the shape of temperature/resistance curve as well.
The first thing one needs to do when adapting a commercial
off the shelf (COTS) indicator to their airplane is to determine
the sensor technology. If a thermistor, then you need to get
the 25C resistance rating, and then the resistance at some
other handy value (boiling water - 100C) and then find
substitute sensors of identical characteristics.
The really cool thing about the linear, solid state sensors
is that they are direct reading, linear, and of known accuracy
out of the box. I'm not discouraging anyone from exploring
adaptation of any COTS temperature display but understand that
there are some inviolate rules by which the sensing technology
is identified and then duplicated so that the display performs
as expected.
Bob . . .
Message 4
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Subject: | Re: Big load on BAT BUS |
There are details that aren't mentioned but I would be cautious with
this. I'd only recommend an additional mini contactor if it is truly
redundant and can't fail the engine. Risk from engine stoppage is likely
far higher than the risk from electrical fire. Other considerations
might be whether the EFI system already has a relay to supply injector
power - many do have an ecu controlled relay that might be easily placed
near the battery. Or is there a mechanical switch in the injector
circuit - there is in my system and it is close to the battery which is
under the instrument panel. The 10 amp fuse is at the battery.
Ideally a redundant engine control system would be powered by its own
power source with no shared wiring.
To understand where I am coming from, understand that the so called
"redundant" electronic engine systems that I've examined do not come
close to true redundancy. Most do not have dual injectors and most share
a single feed to the injectors.
Ken
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 01:31 AM 4/24/2010, you wrote:
>> <jonlaury@impulse.net>
>>
>> In an attempt to keep redundant critical items from the same bus, I
>> have placed the fuse (10-15 amp) for my EFI injectors on the Bat Bus.
>> However, this violates BoB N's limit of
>
> Then you need a "mini-contactor" at the battery
> bus as illustrated in Z-32, except that the
> feeder is for the EFI instead of the E-bus.
>
> It would be nice if it were a solid state
> relay. I believe Eric Jones still offers
> on.
>
> Bob . . .
>
Message 5
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Subject: | Re: Proper SWR meter |
>When you 'rented' the MFJ259, did you include a simplified instruction sheet?
>
>As a proud owner of a MFJ259, I would like a 'cook book' type
>instructions tailored to the OBAM aviation community.
>
>I would like to know all the theory etc but at this time do not have
>the time to invest in learning its complete capability and retaining
>it. I am interested but short on time. My Grandson currently has priority!
>
>I just want to know how to correctly connect it and read the
>SWR. Then some clues as to how to correct it if necessary.
As a matter of fact, I think I did but it's
on the computer in M.L.
I'll see if I can did it up and post it early
next week. If not, I'll write up a new one.
It's pretty straight forward . . . perhaps
a cognizant user of such devices will come
up with a procedure before I get to it.
Bob . . .
Message 6
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Subject: | Re: Big load on BAT BUS |
nuckolls.bob(at)aeroelect wrote:
> At 01:38 AM 4/24/2010, you wrote:
>
> >
> >
> > Never mind about the SS sleeve question. It will only be a 10 gauge
> > wire and I will 18 ga fuselink it at the battery.
> >
> >
>
> This sounds like another "loose cannon"
> implementation of fusible links.
> Bob . . .
Admittedly, it is. And that is why I "disclosed" what I was going to do. It seemed
like a good idea. The feedback here is invaluable as is an occasional slap
upside the head :-)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=295553#295553
Message 7
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Subject: | Re: Surface temperature sensor |
Using a laboratory quality temperature instrument I determined the
readings (at about 10 degree F intervals) of a typical digital display
meat thermometer (10-15 dollar variety some 10 years ago) and found the
error varied well within +/- 3F within the range of interest I
considered appropriate as about 70 to 300F for firewall-forward
applications.
Then by carefully extracting the sensor inside the very tip of the meat
thermometer, I compared it in size and appearance to a variety of
commercially available thermistors and tested several by electrically
substituting them in place of the original until finding the one I
mentioned by source and part number to be apparently identical in
performance over the same range of temperature interest.
After completing the installation in the aircraft, another test with the
lab-quality meter for comparison gave the same ballpark results and also
showed that with the nominal 100K resistance value stated for the
thermistor, the total impedance of the completed installation for any
likely difference in length of wiring between the closest versus
greatest distance of sensors created no error even when wired with the
smallest gauge wire I felt appropriate for use in an aircraft
installation with heat and vibration considerations.
My assumption was/is that the surface mounted electronic circuitry in
the meat thermometer display head performs the necessary compensation
for non linear characteristics of the basic thermistor. Although I was
unable to obtain any data from the thermometer vendor, I assume I was
just lucky enough to perhaps have stumbled upon the exact same-source
thermistor used in the retail unit.
Jim McCulley
========================================================================================
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 09:38 PM 4/23/2010, you wrote:
>> <mcculleyja@starpower.net>
>>
>> Sorry Steve and others...I just thought this subject might be of
>> interest to so few that I should not take up bandwith that those not
>> interested would have to deal with. But, here it is:
>>
>>
>> This is a very accurate system that I tested with a laboratory quality
>> temperature meter and found the accuracy of all my sensors to be two
>> degrees F. It may not be very sophisticated, but it is super-inexpensive
>> and has never malfunctioned. I use it on every flight to assure myself
>> that no changes suddenly occur that could indicate a malfunction.
>>
>> Mine is about a $15 to $25 system that I've operated now for over seven
>> years and upwards of 600 flight hours on it's original internal
>> watch-size battery. The sensors are standard mini glass-encapsulated
>> thermistors available from most electronic supply sources. I used
>> Digi-Key # KC013-ND, 100k ohm units.
>
> How was it that you determined that the 100K devices were
> appropriate to your particular display? Folks should understand
> that there are hundreds of remote temperature measurement
> products on the market. I've see them use thermocouples, solid
> state LINEAR temperature sensors, diodes, the junctions of
> transistors (also a diode) AND thermistors.
>
> http://www.gesensing.com/products/resources/datasheets/ge1.pdf
>
> Thermistors are inexpensive AND rugged but they have the
> distinct disadvantage of being non-linear. So the accurate
> temperature display not only needs to know what the resistance
> of the device is at say 25C, the designer will compensate for
> the shape of temperature/resistance curve as well.
>
> The first thing one needs to do when adapting a commercial
> off the shelf (COTS) indicator to their airplane is to determine
> the sensor technology. If a thermistor, then you need to get
> the 25C resistance rating, and then the resistance at some
> other handy value (boiling water - 100C) and then find
> substitute sensors of identical characteristics.
>
> The really cool thing about the linear, solid state sensors
> is that they are direct reading, linear, and of known accuracy
> out of the box. I'm not discouraging anyone from exploring
> adaptation of any COTS temperature display but understand that
> there are some inviolate rules by which the sensing technology
> is identified and then duplicated so that the display performs
> as expected.
>
> Bob . . .
>
>
>
>
>
>
Message 8
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Subject: | Re: Proper SWR meter |
I wrote:
>When you 'rented' the MFJ259, did you include a simplified instruction sheet?
Bob wrote:
I'll see if I can did it up and post it early
next week. If not, I'll write up a new one.
My response:
Thanks very much! I'll be watching for it from you or anyone.. Earl
Do not Archive.
Message 9
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Subject: | RE: Designing a circuit question |
> I'm fiddling with a variant of the circuit I
> published to convert it to a solid state breaker
> instead of current limiter.
> I'll see if I can publish that variant tomorro evening.
>
> Bob . . .
Hi Bob=2C
If you are still working on this solid state design you talked about=2C I
was wondering if it would be possible to incorporate a feature that allows
the user to set for different loads.
In other words=2C a 2amp setting=2C a 3 amp setting=2C etc=2C etc........
..or did you intend on this=2C anyway?
I'm really looking forward to what you come up with. I definitely plan o
n building it!!
Mike Welch
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_________________________________________________________________
The New Busy is not the old busy. Search=2C chat and e-mail from your inbox
.
http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:O
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Message 10
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Subject: | Z-12 Power Grid Behavior |
Hello Bob K. and anyone else who wants to weigh in.
Could I please get confirmation that I'm interpreting the Z-12 power grid
design behavior correctly (Z-12 = Main Alt, Standby Alt, One Battery, Main
Bus, E-Bus) represented in these statements below?
. One can normally fly with E-Bus feed switch ON since an alternator
energized Main Bus is at a higher voltage than the battery and it will feed
the E-Bus thru the diode when operating. So even if both alternators fail
and battery contactor failed the E-Bus will receive battery power without
any action required from the pilot.
. If the Battery Contactor Relay is opened, isolating the battery
from the Main Bus, while either alternator is operating, the alternator will
continue to provide good power to the Main Bus and E-Bus without the battery
in the circuit.
Are these interpretations correct?
In the bullet two scenario where the engine is running, an alternator is
making power, and the battery contactor relay is open, will there be any
power quality or stability issues with the electrical system without the
battery in the circuit?
Thanks,
Valin
Message 11
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Subject: | Re: Surface temperature sensor |
>Then by carefully extracting the sensor inside the very tip of the
>meat thermometer, I compared it in size and appearance to a variety
>of commercially available thermistors and tested several by
>electrically substituting them in place of the original until
>finding the one I mentioned by source and part number to be
>apparently identical in performance over the same range of
>temperature interest.
Aha! Then there was a rational exercise to pick a
thermistor that matched the operating characteristics
of the device being cloned.
This is the point that we needed to make clear
to our readers. There are thousands of thermistor
parts of which only a few will directly replace the
sensor used in a randomly selected off the shelf
thermometer.
I assume I was just lucky enough to perhaps have stumbled upon the
exact same-source thermistor used in the retail unit.
Don't know about 'luck'. You can measure the 25C
resistance point for device under study. You could
also measure it's resistance at say, two other points
over the range of interest . . . like 0C (ice point)
and 100C (boiling point). Then by studying the
temperature/resistance transfer curves (or as you
did, experimentation) you can find a match. Afterr
that, you're home free. As you've described, you
can switch as many remote sensors in to the display
as you like.
The only thing I wanted to make clear was that
unlike thermocouples and factory calibrated
temperature sensors, thermistors are a breed
unto themselves. The successful user will have
to learn a few dditions to their back of
electro-whizzy tricks.
Thanks for sharing your experience in this
discussion!
Bob . . .
Message 12
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Subject: | Re: Big load on BAT BUS |
> > This sounds like another "loose cannon"
> > implementation of fusible links.
> > Bob . . .
>
>
>Admittedly, it is. And that is why I "disclosed" what I was going to
>do. It seemed like a good idea. The feedback here is invaluable as
>is an occasional slap upside the head :-)
Naw, just a short "time out" in "now you
know better corner". Folks on this List
strive to be gentle but clear teachers. This
should be an experience of discovery not
of discomfort. Thanks for sharing.
Bob . . .
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