Today's Message Index:
----------------------
1. 01:35 AM - Re: Capacitive Fuel Level Sensor - How do they work? (user9253)
2. 06:34 AM - Re: Capacitive Fuel Level Sensor - How do they work? (thomas sargent)
3. 08:00 AM - Fuel (Paul Millner)
4. 08:44 AM - Re: Capacitive Fuel Level Sensor - How do they work? (jonlaury)
5. 09:34 AM - Re: KX155/165 Crimp Contacts (Robert L. Nuckolls, III)
6. 10:34 AM - Re: Re: Capacitive Fuel Level Sensor - How do they work? (David)
7. 10:34 AM - Re: KX155/165 Crimp Contacts (Jim Corner)
8. 10:52 AM - Re: Re: Capacitive Fuel Level Sensor - How do they work? (David)
9. 11:07 AM - Re: Re: Capacitive Fuel Level Sensor - How do they work? (Robert L. Nuckolls, III)
10. 11:14 AM - Composite aircraft grounding systems. (MikeDunlop)
11. 11:17 AM - Re: Wiring Harness (Robert L. Nuckolls, III)
12. 11:17 AM - Re: Re: Capacitive Fuel Level Sensor - How do they work? (RGent1224@aol.com)
13. 11:46 AM - Re: Composite aircraft grounding systems. (rparigoris)
14. 12:10 PM - Headset microphone level reducer (Etienne Phillips)
15. 12:13 PM - Re: Re: Capacitive Fuel Level Sensor - How do they work? (paul wilson)
16. 01:39 PM - Re: Composite aircraft grounding systems. (Robert L. Nuckolls, III)
17. 03:18 PM - Re: Re: Capacitive Fuel Level Sensor - How do they work? (Bob McCallum)
18. 03:36 PM - Re: Headset microphone level reducer (Robert L. Nuckolls, III)
19. 06:28 PM - Re: Wiring Harness (Dan Sherburn)
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they work? |
http://www.discovercircuits.com/PDF-FILES/capgage.pdf
A capacitor is constructed of two parallel conductors insulated from each other.
The amount of capacitance is related to the distance between the conductors
and the type of insulation. The insulation between the conductors of a capacitance
fuel level probe consists of air and/or fuel. As the fuel lever changes,
so does the capacitance. The capacitance is part of an oscillator circuit.
As the capacitance changes, so does the oscillator frequency. The frequency
is converted to a voltage that is displayed with a fuel gauge.
The advantage of a capacitance type fuel level probe is that there are no moving
parts. The disadvantage is that the gauge must be calibrated each time that
the type of fuel is changed because unleaded fuel and leaded fuel and gasohol
each have different insulating properties. When the fuel tank is almost full,
the capacitance fuel gauge will display different levels depending on the
type of fuel in the tank. When the tank is almost empty, the fuel gauge will
be more accurate because air is now the insulating medium and the probe does not
know or care what type of fuel used to be in the tank.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=362211#362211
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they work? |
You just make a capacitor where the gap between the two plates of the cap
(or the gap between a central wire and an outer tube, or whatever the
geometry of the cap is) is open to the gasoline in the tank. The gasoline
serves as the electrolyte in the capacitor. If the cap. is completely
submerged, then the gap between the 2 parts of the cap is completely full
of electrolyte and the capacitance of the the thing is maximized. As the
gasoline level drops, the portion of the gap that is filled with fuel , and
hence has elevated capacitance, decreases. So the overall capacitance of
the capacitor changes with fuel level.
So you put this cap. into a circuit that allows you to measure the
capacitance. The easiest way is to make an oscillator circuit and measure
the frequency of the oscillator. The frequency of the oscillator will
change with the fuel level.
The problem is that it's hard to make a cap. whose capacitance varies a lot
with the presence or absence of the gas. The variation in capacitance is
usually in the range of a few hundred picofarads - not much. So the
circuit that measures the capacitance has to be right there at the
capacitor because if it was 10 feet away, the wires going to the cap would
have way more capacitance than the capacitor itself. (I understand they
actually made this mistake on the A-10 fuel systems. Made them very flaky
and failure prone.)
I have the Princeton capacitive fuel sensors in my 6A and wish that I
didn't. (They're the tube with central wire type of design) They show
full until you get down to the last 5 or 6 gallons of gas. So if I see
them "off the peg" much at all it means I have very little fuel left.
Fortunately my fuel flow integrator in the VM-1000 engine monitor I have is
accurate. Also, I understand they get badly confused if any water gets
into them. If I were to change from 100LL to auto gas they would have to
be recalibrated because autogas has significantly different electrolyte
properties. (Recalibrating is doable but kind of a pain since you have to
drain the tank.) If I had it to do over, I'd use the ancient float with
potentiometer style of fuel level transducer.
The Princeton probes sold by Aircraft spruce were designed by a guy named
Todd who actually works for Grand Rapids, or at least did the last time I
talked to him. Well, I inferred that he designed them. I'm guessing he did
that before he joined (or formed?) GRT and still performs as "Princeton" on
the side. - just a theory on my part, having been in the electronics
business.
On Sun, Jan 1, 2012 at 10:13 PM, Jeff Luckey <JLuckey@pacbell.net> wrote:
> JLuckey@pacbell.net>
>
>
> How do capacitive fuel sensors work?
>
> Can someone give me the general theory of operation, what type of signal
> does the transducer produce? Why do I want one? Etc?
>
> TIA
>
>
--
Tom Sargent
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Sent from my iPad
On Jan 2, 2012, at 1:31 AM, user9253 <fran4sew@banyanol.com> wrote:
> unleaded fuel and leaded fuel and gasohol each have different insulating properties
I can understand ethanol, being polar, having a quite different dielectric constant.
It seems unlikely that adding a very small amount of non-conducting tetra
ethyl lead to gasoline would change the dielectric properties. Do you have
a reference?
Paul
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they work? |
The electronics have been explained by Joe and Sarg, and Sarg elaborated on his
experience with Princeton probes.
But the reason for installing cap probes has gone unanswered.
Cap probes allow for fuel measurement of irregularly shaped tanks. My fuel bays
in the wing change in taper, both in depth and width, in addition to the whole
tank sitting at an angle (dihedral), making any kind of accurate measurement
impossible over the tank range when using a linear type (float) sensor.
I have installed 8' Centroid probes. Haven't fueled them yet.
They come with two small potentiometers built in to adjust the empty and full points.
Available in 0-5v output and various resistance output so you can use them
with your existing gauge.
http://www.centroidproducts.com/tableofc.htm
Not a recommendation, just a resource, as I have no real world experience with
this product, . YMMV.
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=362237#362237
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| Subject: | Re: KX155/165 Crimp Contacts |
At 12:41 PM 12/31/2011, you wrote:
>Hello!
>
>Does anyone know the actual part number of the contacts used for the
>KX155 connectors? I know they're AMP or Molex, but not the
>manufacturer part number....want to avoid paying the exorbitant
>prices when buying them thru avionics channels.
>
>Appreciate any info! Want to stock up.
This style connector was very popular from the
time that etched circuit boards became commonplace
and up until about 20 years ago. The really cool thing
about this connector technology was the ability to
fabricate the male portion of the wiring mate-up
right onto the etched circuit board. This often
added a demand for special treatment of the male
"pins" to have them gold plated for resistance to
corrosion.
AMP, Molex, Cinch, and dozens of others rose to the
opportunity and offered mating female connectors
in a variety of pitches . . . but 0.156" spacing
was popular. This technology is still used in computers
as many of the accessory boards we plug into a
mother board have card edge connectors but they tend
to be much finer pitch.
This configuration of connector fell out of favor for airframe
harnesses due to the lack of environmental robustness.
No new radios have been built with this style harness
connector in quite some time.
As one might expect, most if no all producers of this
connector have discontinued manufacturing new parts. Due
to past popularity, there are still many parts of the style
in new-old-stock inventories but specific parts are becoming
more difficult to find every year.
The pins are much easier to find than some sizes of
housing. The pins you're looking for are Molex 4366 series
p/n 08-05-0302 20-18AWG pins with gold flash.
http://tinyurl.com/6nkcv5n
Mouser still seems to have these on hand in some
quantity.
http://tinyurl.com/6sfazya
For individuals looking for a work-around to replace one of
these connectors (many popular radios using 156 card edge
connectors are still in service) consider this or some
similar work around.
http://tinyurl.com/6s949t3
http://tinyurl.com/7zqx4r6
http://tinyurl.com/6towcwh
156 pitch connectors in various sizes and styles are readily
available as new-old-stock and can often be adapted to
your task of keeping a serviceable radio airworthy.
For a general posting of data on the Molex/Waldom series
of connectors see:
http://tinyurl.com/7t6jjsc
Bob . . .
Message 6
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they |
work?
Are they reliable and relatively accurate?
David
user9253 wrote:
> --> AeroElectric-List message posted by: "user9253"<fran4sew@banyanol.com>
>
> http://www.discovercircuits.com/PDF-FILES/capgage.pdf
> A capacitor is constructed of two parallel conductors insulated from each other.
The amount of capacitance is related to the distance between the conductors
and the type of insulation. The insulation between the conductors of a capacitance
fuel level probe consists of air and/or fuel. As the fuel lever changes,
so does the capacitance. The capacitance is part of an oscillator circuit.
As the capacitance changes, so does the oscillator frequency. The frequency
is converted to a voltage that is displayed with a fuel gauge.
> The advantage of a capacitance type fuel level probe is that there are no
moving parts. The disadvantage is that the gauge must be calibrated each time
that the type of fuel is changed because unleaded fuel and leaded fuel and gasohol
each have different insulating properties. When the fuel tank is almost
full, the capacitance fuel gauge will display different levels depending on the
type of fuel in the tank. When the tank is almost empty, the fuel gauge will
be more accurate because air is now the insulating medium and the probe does
not know or care what type of fuel used to be in the tank.
> Joe
>
> --------
> Joe Gores
>
>
>
--
Tell the truth. Be honest. Be responsible to and for yourself.
I liked America when it was free and it's people were responsible and had morals.
Every gram of cocaine you buy from elsewhere contributes to an innocent being murdered
in Central and South America. Grow your own or Stop taking it.
Message 7
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| Subject: | Re: KX155/165 Crimp Contacts |
On 2012-01-02, at 10:31 AM, Robert L. Nuckolls, III wrote:
> At 12:41 PM 12/31/2011, you wrote:
>
>> Hello!
>>
>> Does anyone know the actual part number of the contacts used for the
KX155 connectors? I know they're AMP or Molex, but not the manufacturer
part number....want to avoid paying the exorbitant prices when buying
them thru avionics channels.
>>
>> Appreciate any info! Want to stock up.
>
> This style connector was very popular from the
> time that etched circuit boards became commonplace
> and up until about 20 years ago. The really cool thing
> about this connector technology was the ability to
> fabricate the male portion of the wiring mate-up
> right onto the etched circuit board. This often
> added a demand for special treatment of the male
> "pins" to have them gold plated for resistance to
> corrosion.
>
> AMP, Molex, Cinch, and dozens of others rose to the
> opportunity and offered mating female connectors
> in a variety of pitches . . . but 0.156" spacing
> was popular. This technology is still used in computers
> as many of the accessory boards we plug into a
> mother board have card edge connectors but they tend
> to be much finer pitch.
>
> This configuration of connector fell out of favor for airframe
> harnesses due to the lack of environmental robustness.
> No new radios have been built with this style harness
> connector in quite some time.
>
> As one might expect, most if no all producers of this
> connector have discontinued manufacturing new parts. Due
> to past popularity, there are still many parts of the style
> in new-old-stock inventories but specific parts are becoming
> more difficult to find every year.
>
> The pins are much easier to find than some sizes of
> housing. The pins you're looking for are Molex 4366 series
> p/n 08-05-0302 20-18AWG pins with gold flash.
>
> http://tinyurl.com/6nkcv5n
>
> Mouser still seems to have these on hand in some
> quantity.
>
> http://tinyurl.com/6sfazya
>
> For individuals looking for a work-around to replace one of
> these connectors (many popular radios using 156 card edge
> connectors are still in service) consider this or some
> similar work around.
>
> http://tinyurl.com/6s949t3
> http://tinyurl.com/7zqx4r6
> http://tinyurl.com/6towcwh
>
> 156 pitch connectors in various sizes and styles are readily
> available as new-old-stock and can often be adapted to
> your task of keeping a serviceable radio airworthy.
>
> For a general posting of data on the Molex/Waldom series
> of connectors see:
>
> http://tinyurl.com/7t6jjsc
>
> Bob . . .
>
>
>
>
Message 8
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they |
work?
Wow. That site refuses to allow me a connection, even to their home page.
David M.
jonlaury wrote:
> --> AeroElectric-List message posted by: "jonlaury"<jonlaury@impulse.net>
>
> The electronics have been explained by Joe and Sarg, and Sarg elaborated on his
experience with Princeton probes.
>
> But the reason for installing cap probes has gone unanswered.
> Cap probes allow for fuel measurement of irregularly shaped tanks. My fuel bays
in the wing change in taper, both in depth and width, in addition to the whole
tank sitting at an angle (dihedral), making any kind of accurate measurement
impossible over the tank range when using a linear type (float) sensor.
> I have installed 8' Centroid probes. Haven't fueled them yet.
> They come with two small potentiometers built in to adjust the empty and full
points. Available in 0-5v output and various resistance output so you can use
them with your existing gauge.
>
> http://www.centroidproducts.com/tableofc.htm
>
> Not a recommendation, just a resource, as I have no real world experience with
this product, . YMMV.
>
> John
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=362237#362237
>
>
>
--
Tell the truth. Be honest. Be responsible to and for yourself.
I liked America when it was free and it's people were responsible and had morals.
Every gram of cocaine you buy from elsewhere contributes to an innocent being murdered
in Central and South America. Grow your own or Stop taking it.
Message 9
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they |
work?
At 10:41 AM 1/2/2012, you wrote:
The electronics have been explained by Joe and Sarg, and Sarg
elaborated on his experience with Princeton probes.
But the reason for installing cap probes has gone unanswered.
Cap probes allow for fuel measurement of irregularly shaped tanks. My
fuel bays in the wing change in taper, both in depth and width, in
addition to the whole tank sitting at an angle (dihedral), making any
kind of accurate measurement impossible over the tank range when
using a linear type (float) sensor.
I have installed 8' Centroid probes. Haven't fueled them yet.
They come with two small potentiometers built in to adjust the empty
and full points. Available in 0-5v output and various resistance
output so you can use them with your existing gauge.
http://www.centroidproducts.com/tableofc.htm
Not a recommendation, just a resource, as I have no real world
experience with this product, . YMMV.
Capacitively sensed liquid level measurement
has been around for a very long time. This patent
dated in 1937 speaks to liquid level control by
exploiting the variability of capacitance due to
presence or absence of liquid between two plates:
http://tinyurl.com/8xqfqlo
This fuel level meter patent dated 1945 goes to the
idea of calibrating a pointer on an instrument to show
liquid level in the fuel tanks
http://tinyurl.com/6qwfdyr
This idea patented in 1952 speaks to the technique
of tailoring a probe to compensate for tank shape
with the idea of providing a change in capacitance
that is linear and proportional to useable volume
of liquid in the tank.
http://tinyurl.com/6ogp4ve
This one patented in 1965 was aimed at the automotive
market. Too bad it didn't catch on. The float style
gauge in my 2002 Kia is no better than the one in
my 1941 Pontiac.
http://tinyurl.com/86mseoz
This 1973 patent speaks to one of dozens of techniques
for resolving differences in small changes of capacity
into corresponding changes of current to some panel
mounted indicator.
http://tinyurl.com/73dgo2n
The first time I saw a delta-C fuel gaging system was
on the B-52 and 1962. I didn't work that system
but knew fellow techs who did. Got to peek inside
one of the black boxes in the lab . . . lots of vacuum
tubes.
Here's an exemplar schematic for a system several
generations newer than the one in 1960's B-52. These
are hand-built, and a gazillion parts most of
which can affect stability and accuracy of the gaging
system. This configuration went into production in the
early 1980's.
http://tinyurl.com/7hbwkr6
http://tinyurl.com/6mpgdeo
The very last new design study I did for Hawker-Beech was
to explore ways to replace the schematics above. This
prompted a study that continues to this day . . . that has
poor likelihood of finding its way onto an HBC aircraft.
Nonetheless, I can report to you that it takes less than
3% of the parts count to craft a capacitance fuel
gaging system that uses simple, non-compensated capacity
probes. It can be calibrated to the volume vs. shape variances
in software. The system can include a reference probe in
the bottom of the tank that allows the system to measure
dielectric properties of the current load of fuel that
varies with mix and temperature. The best thing is that
there are less than 5 components that have a strong
influence on calibration drifts with temperature and
time.
The project is on a back burner but the client hasn't
abandoned the program . . . if and when the aviation
community climbs out of the crapper, I'm hoping that
we can spool this effort up again.
In any case, know that most of what's being offered
today has roots that go back many decades. Do a search of
http://freepatentsonline.com and you'll find a wealth of
history along with examples that range from rather practical
to bizarre in terms of performance. But devices as
simple as a $1 PIC micro-controller . . . fitted with
well crafted software can do a very good job of
telling you how much fuel is in the tank. Further,
cost of manufacturing is a tiny fraction of that
invested in systems flying on virtually all GA aircraft
today.
Bob . . .
Message 10
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| Subject: | Composite aircraft grounding systems. |
For Bob Nuckolls (or anyone else with knowledge of composite aircraft grounding
systems),
I have recently bought your book, 'The AeroElectric Connection' (12th Edition)
and have also looked at all the FAQ documents and archive posts such as 'Airframe
Grounding' etc. Very, very interesting reading.
I'm starting the electrical system on a Rutan Long-EZ project (all composite as
you will already know). The original builder had built in one copper 1/2 inch
ID tube from front to back and I'm contemplating using it for possibly two purposes,
a) a main earth rail. b) a conduit to carry the main power cable to the
starter. The battery is in the nose and the distance from battery to starter
(B&C light weight) is 14 ft (4.3 metre). Cable suppliers in the U.K. shows #4
as being suitable for starters but B&C responded to my question saying for a
Long-EZ use #2, presumably for voltage drop reasons.
I've settled on the Z-12 setup with a automotive alternator and B&C LR-3 controller
as primary power with a B&C SD-8 system for secondary power. I would like
to seek valued opinions on the following:
Questions:
1. Would having a main power cable inside a copper ground tube generate unforseen
problems (besides lots of sparks if shorted out!).
2. Can I use welding cable instead of the very heavy and very expensive #2 Tefzel
coated aviation cable (circa $15 per foot in the U.K.)
3. Should the Starter solenoid be close to the battery or on the firewall (live
power in the cable only at starting or all the time)
My main concern and objective at the moment is to establish a suitable and reliable
earthing system before moving on to other matters.
Bob, many thanks for your excellent book and resources.
Regards
Mike Dunlop (U.K.)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=362258#362258
Message 11
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| Subject: | Re: Wiring Harness |
At 12:02 AM 1/2/2012, you wrote:
Dan,
I am just starting my wiring diagram on a Tundra w/ IO-360. I have
decided to follow Bob's suggestion to use the Z-12 schematic (dual
alternators, single battery) and I'm assembling the various parts.
While I have worked on the wiring of two Glastars I have never done
anything like this and I am looking to our group for ideas. I have
Bob's book and continue to study it. His statement about the
difference between a 'Schematic' drawing and a 'mechanical' drawing
has really hit home. Just knowing which components belong in the
engine compartment (contactors, shunts, current limiters, ??) and
which to mount on the cockpit side of the firewall and then which to
mount on the panel itself would be a great start on doing a
mechanical drawing. These thoughts may seem vary 'logical' to those
with experience but no so to this novice.
Anyway, I sure appreciate your questions and the answers that have
come forth. Since I could not find your schematic on the list I look
forward to you sending it direct. I will begin to check the archives
for topics on this.
Jim Kinninger
Consider this also:
I don't think I've written about this before but
it was offered in most if not all of my weekend
seminars.
One problem with crafting bundles 'in place' is
getting the first few wires to hold the shape and
routing in the airplane. Lay out your complex bundle
pathways by laying down supporting guide-wires fabricated from
10AWG single strand copper from Home Depot or similar
supplier. Support the guide-wire on small plastic clamps
using the same holes that will ultimately mount the
final compliment of support clamps.
Build your bundles onto these guide wires using tye-wraps
to bring it all together. Cut of the older wraps as new ones
are added. When you're all done, it's a simple matter to
put the final set of wraps or ties on the bundle after
you've cut the guide-wire from the bundle interior. The
temporary support clamps for the guide-wire are replaced
with the real clamps using the same mounting holes.
Building on top of a guide-wire "skeleton" can go a
long way to having your finished wire bundles look like
they came off a well crafted form board.
Bob . . .
Message 12
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they |
work?
You're not along
Dick
In a message dated 1/2/2012 12:53:43 P.M. Central Standard Time,
ainut@knology.net writes:
--> AeroElectric-List message posted by: David <ainut@knology.net>
Wow. That site refuses to allow me a connection, even to their home page.
David M.
jonlaury wrote:
> --> AeroElectric-List message posted by:
"jonlaury"<jonlaury@impulse.net>
>
> The electronics have been explained by Joe and Sarg, and Sarg elaborated
on his experience with Princeton probes.
>
> But the reason for installing cap probes has gone unanswered.
> Cap probes allow for fuel measurement of irregularly shaped tanks. My
fuel bays in the wing change in taper, both in depth and width, in addition
to the whole tank sitting at an angle (dihedral), making any kind of
accurate measurement impossible over the tank range when using a linear type
(float) sensor.
> I have installed 8' Centroid probes. Haven't fueled them yet.
> They come with two small potentiometers built in to adjust the empty and
full points. Available in 0-5v output and various resistance output so you
can use them with your existing gauge.
>
> http://www.centroidproducts.com/tableofc.htm
>
> Not a recommendation, just a resource, as I have no real world
experience with this product, . YMMV.
>
> John
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=362237#362237
>
>
>
--
Tell the truth. Be honest. Be responsible to and for yourself.
I liked America when it was free and it's people were responsible and had
morals.
Every gram of cocaine you buy from elsewhere contributes to an innocent
being murdered in Central and South America. Grow your own or Stop taking
it.
Message 13
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| Subject: | Re: Composite aircraft grounding systems. |
Hi Mike
I'm building a composite Europa. There's a builder in Canada that put Eric Jones
copper clad wire:
http://www.periheliondesign.com/fatwires.htm
inside a copper pipe as you suggest. I don't think he's flying yet, but here are
a few pics:
http://www.europaowners.org/forums/gallery2.php?g2_itemId=78200
I think the yellow with green is heat shrink he added.
The aluminium wire is expensive but will save you some weight. It is not very flexable and fatugues more easily than thin stranded copper. If you need to make hard turns, best use welding cable for that area? I looked into welding cable and www.mcmaster is one resource. The #2 CCA is thicker in diameter compared to Tefzel, but has approx the same resistance.
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=362262#362262
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| Subject: | Headset microphone level reducer |
Hi All
I have two dissimilar headsets that have very different microphone output levels.
The one headset is an oldish basic Avcomm model, and the other is a new child-sized
one. My MGL radio/intercom doesn't have the ability to reduce the volume
of the new headset adequately.
I've never worked with electret microphones before, so am not sure how to build
a signal reducer. I have noticed that they are polarity sensitive, which leads
me to expect some phantom power is required...?
I need to reduce the volume by about 15dB (according to the MGL radio) to match
the Avcomm. Ideally, I'd like to be able to build a passive circuit that I can
squeeze into the headset itself, rather than an interface box or off-the-shelf
device. This will allow me to use the new headset in other aircraft as the
Avcomm's seem to play nicely with other major brands.
If anyone has some insight, I'd be most appreciative!
Thanks
Etienne
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they |
work?
The boat people deal with crazy shaped tanks. Here is one example
that uses a low tech float/resistor and a smart meter head.
http://www.cruzpro.com/products.html#HEADINGE
PaulW
=====
>At 10:41 AM 1/2/2012, you wrote:
>
>The electronics have been explained by Joe and Sarg, and Sarg
>elaborated on his experience with Princeton probes.
>
>But the reason for installing cap probes has gone unanswered.
>Cap probes allow for fuel measurement of irregularly shaped tanks.
>My fuel bays in the wing change in taper, both in depth and width,
>in addition to the whole tank sitting at an angle (dihedral), making
>any kind of accurate measurement impossible over the tank range when
>using a linear type (float) sensor.
>I have installed 8' Centroid probes. Haven't fueled them yet.
>They come with two small potentiometers built in to adjust the empty
>and full points. Available in 0-5v output and various resistance
>output so you can use them with your existing gauge.
>
>http://www.centroidproducts.com/tableofc.htm
>
>Not a recommendation, just a resource, as I have no real world
>experience with this product, . YMMV.
Message 16
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| Subject: | Re: Composite aircraft grounding systems. |
M: Bob,
I've just joined the AeroElectric-List and will post the following
when the acount is activated...
I have recently bought your book, 'The AeroElectric Connection' (12th
Edition) and have also looked at all the FAQ documents and archive
posts such as 'Airframe Grounding' etc. Very, very interesting reading.
Thank you.
I'm starting the electrical system on a Rutan Long-EZ project (all
composite as you will already know). The original builder had built
in one copper 1/2 inch ID tube from front to back and I'm
contemplating using it for possibly two purposes, a) a main earth
rail. b) a conduit to carry the main power cable to the starter. The
battery is in the nose and the distance from battery to starter (B&C
light weight) is 14 ft (4.3 metre). Cable suppliers in the U.K. shows
#4 as being suitable for starters but B&C responded to my question
saying for a Long-EZ use #2, presumably for voltage drop reasons.
Correct.
I've settled on the Z-12 setup with a automotive alternator and B&C
LR-3 controler as primary power with a B&C SD-8 system for secondary
power. I would like to seek your valued opinion on the following:
Then you don't want Z-12 but Z-13/8.
Questions:
1. Would having a main power cable inside a copper ground tube
generate unforseen problems.
No, But you do want to craft your tube-to-wiring connections
by soldering copper wrap-around flag terminals to the copper tube.
2. Can I use welding cable instead of the very heavy and expensive #2
Tefzel coated aviation cable (circa $15 per foot in the U.K.)
Absolutely. In fact I prefer it.
3. Should the Starter solinoid be close to the battery or on the
firewall (live power in the cable only at starting or all the time)
Close to the starter. Then use the same feeder
to bring b-lead power up front from the main alternator.
But a current limiter in the b-lead connecting right
were it attaches to the hot-side of the starter contactor
on the firewall.
My main concern and objective at the moment is to establish a
suitable earthing system before moving on to other matters. I could
go on asking questions like this all day but I'm sure you have other
things to do and I need to concentrate on getting this bit sorted first.
The conduit ground system is fine.
Many thanks for your excellent book and resources.
I'm pleased that you find it a good value . . .
Bob . . .
Message 17
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| Subject: | Re: Capacitive Fuel Level Sensor - How do they |
work?
The Centroid Products site works perfectly for me by following the link
provided by John.
Here is the link he provided again in case this works better for someone
than the original.
http://www.centroidproducts.com/tableofc.htm
and here is their home page if this helps.
http://www.centroidproducts.com <http://www.centroidproducts.com/>
Good luck
Bob McC
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
RGent1224@aol.com
Sent: Monday, January 02, 2012 2:14 PM
Subject: Re: AeroElectric-List: Re: Capacitive Fuel Level Sensor - How do
they work?
You're not along
Dick
In a message dated 1/2/2012 12:53:43 P.M. Central Standard Time,
ainut@knology.net writes:
Wow. That site refuses to allow me a connection, even to their home page.
David M.
jonlaury wrote:
> --> AeroElectric-List message posted by: "jonlaury"<jonlaury@impulse.net>
>
> The electronics have been explained by Joe and Sarg, and Sarg elaborated
on his experience with Princeton probes.
>
> But the reason for installing cap probes has gone unanswered.
> Cap probes allow for fuel measurement of irregularly shaped tanks. My fuel
bays in the wing change in taper, both in depth and width, in addition to
the whole tank sitting at an angle (dihedral), making any kind of accurate
measurement impossible over the tank range when using a linear type (float)
sensor.
> I have installed 8' Centroid probes. Haven't fueled them yet.
> They come with two small potentiometers built in to adjust the empty and
full points. Available in 0-5v output and various resistance output so you
can use them with your existing gauge.
>
> http://www.centroidproducts.com/tableofc.htm
>
> Not a recommendation, just a resource, as I have no real world experience
with this product, . YMMV.
>
> John
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=362237#362237
>
>
>
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Message 18
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| Subject: | Re: Headset microphone level reducer |
At 12:29 PM 1/2/2012, you wrote:
<etienne.phillips@gmail.com>
Hi All
I have two dissimilar headsets that have very different microphone
output levels. The one headset is an oldish basic Avcomm model, and
the other is a new child-sized one. My MGL radio/intercom doesn't
have the ability to reduce the volume of the new headset adequately.
I've never worked with electret microphones before, so am not sure
how to build a signal reducer. I have noticed that they are polarity
sensitive, which leads me to expect some phantom power is required...?
Are both microphones intended for interface to an aviation
transmitter/intercom inputs? 15 db is a BIG difference.
I need to reduce the volume by about 15dB (according to the MGL
radio) to match the Avcomm. Ideally, I'd like to be able to build a
passive circuit that I can squeeze into the headset itself, rather
than an interface box or off-the-shelf device. This will allow me to
use the new headset in other aircraft as the Avcomm's seem to play
nicely with other major brands.
An aviation microphone, is powered by a bias current
applied to a combination of ELECTRONICS as an amplifier
and the electret microphone element.
If anyone has some insight, I'd be most appreciative!
The goal is to reduce magnitude of signal voltage
without materially upsetting the DC power that is
supplied to the microphone's electronics. I would
suggest a resisteor in series with say a 100uF/10v
capacitor tied right across the microphone's signal/
power wires. We know that the microphone's AC output
impedance is some finite value. Let's assume 1000 ohms.
Okay, you're wanting to attenuate the AC signal by
about 2/3. So the resistor in series with the capacitor
will be 500 ohms or less. This is just an guess/example
and but it's in the ballpark. You can fiddle with the
value of the fixed resistor until the two microphones
demonstrate near equal performance.
Having a capacitor in series with the resistor will
keep the AC load resistor from also affecting the
DC power that comes out of the radio or intercom to
power the microphone.
Bob . . .
Message 19
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| Subject: | Re: Wiring Harness |
Great idea on how to construct the wire harnes.....Thanks for the
information!
Dan
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Monday, January 02, 2012 2:14 PM
Subject: Re: AeroElectric-List: Wiring Harness
> <nuckolls.bob@aeroelectric.com>
>
> At 12:02 AM 1/2/2012, you wrote:
> Dan,
> I am just starting my wiring diagram on a Tundra w/ IO-360. I have decided
> to follow Bob's suggestion to use the Z-12 schematic (dual alternators,
> single battery) and I'm assembling the various parts. While I have worked
> on the wiring of two Glastars I have never done anything like this and I
> am looking to our group for ideas. I have Bob's book and continue to study
> it. His statement about the difference between a 'Schematic' drawing and a
> 'mechanical' drawing has really hit home. Just knowing which components
> belong in the engine compartment (contactors, shunts, current limiters,
> ??) and which to mount on the cockpit side of the firewall and then which
> to mount on the panel itself would be a great start on doing a mechanical
> drawing. These thoughts may seem vary 'logical' to those with experience
> but no so to this novice.
> Anyway, I sure appreciate your questions and the answers that have come
> forth. Since I could not find your schematic on the list I look forward to
> you sending it direct. I will begin to check the archives for topics on
> this.
> Jim Kinninger
>
> Consider this also:
>
> I don't think I've written about this before but
> it was offered in most if not all of my weekend
> seminars.
>
> One problem with crafting bundles 'in place' is
> getting the first few wires to hold the shape and
> routing in the airplane. Lay out your complex bundle
> pathways by laying down supporting guide-wires fabricated from
> 10AWG single strand copper from Home Depot or similar
> supplier. Support the guide-wire on small plastic clamps
> using the same holes that will ultimately mount the
> final compliment of support clamps.
>
> Build your bundles onto these guide wires using tye-wraps
> to bring it all together. Cut of the older wraps as new ones
> are added. When you're all done, it's a simple matter to
> put the final set of wraps or ties on the bundle after
> you've cut the guide-wire from the bundle interior. The
> temporary support clamps for the guide-wire are replaced
> with the real clamps using the same mounting holes.
>
> Building on top of a guide-wire "skeleton" can go a
> long way to having your finished wire bundles look like
> they came off a well crafted form board.
>
>
> Bob . . .
>
>
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