Today's Message Index:
----------------------
1. 02:29 AM - Re: Z-12, Z-13/8 or a bit of both! (MikeDunlop)
2. 06:12 AM - Re: Grounding - 28 to 12v down-converter (ROGER & JEAN CURTIS)
3. 08:21 AM - Re: Grounding - 28 to 12v down-converter (Robert L. Nuckolls, III)
4. 11:24 AM - Fuses instead of breakers (Jeff Page)
5. 01:30 PM - Re: Fuses instead of breakers (Robert L. Nuckolls, III)
6. 01:44 PM - Re: Fuses instead of breakers (B Tomm)
7. 04:34 PM - Antenna Installation Question (tomcostanza)
8. 05:01 PM - Re: Antenna Installation Question (Charlie England)
9. 06:33 PM - Re: Antenna Installation Question (Noel Loveys)
10. 06:39 PM - Re: Antenna Installation Question (tomcostanza)
11. 07:53 PM - Re: Grounding - 28 to 12v down-converter (Paul Millner)
12. 08:13 PM - Re: Re: Antenna Installation Question (Robert L. Nuckolls, III)
13. 08:38 PM - Re: Fuses instead of breakers (Bill Watson)
14. 09:33 PM - Re: Re: Weak and Static on Transmission (jerb)
Message 1
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Subject: | Re: Z-12, Z-13/8 or a bit of both! |
Bob,
Thanks for the reply.
Now I understand, I will be using the Z-13/8 architecture.
Let me try and be more informative about how I envisage the earth conduit setup.
I'm building a Long-EZ with a Odyssey PC925 battery in the nose section.
The positive cables will run from the battery to the master switch in the nose
section (6 to 7 inches), from the master switch through the earth conduit to the
starter solenoid way back on the firewall (about 10 ft), then from solenoid
to starter.
The earth cable will run from the battery to the copper tab on the front of the
earth conduit, just behind the nose section (30 inches). The earth is then picked
up from the rear copper tab of the earth conduit, on the engine side of
the firewall, by a copper braided strap between conduit and engine. So I presume
(dangerous thing to do!) the cranking current runs through the copper conduit.
My question was:
What is the minimum size cable can I use from the copper tab on the FRONT of the
earth conduit tab (just behind the nose section) to the instrument earth bus
(approx 18-20 inches in length)
MikeD (U.K.)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=364653#364653
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Subject: | Grounding - 28 to 12v down-converter |
Note:
-Input/output negative cannot be mixed with or together
Maybe my "Chinglish" is not up to the task of translating
that?
Paul
I'm not schooled in "Chinglish" either but
perhaps this means that you cannot stack this power supply on top of
another
to get a higher voltage out. In other words the ground is not floating.
Roger
Message 3
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Subject: | Grounding - 28 to 12v down-converter |
At 08:07 AM 1/24/2012, you wrote:
> Note:
> -Input/output negative cannot be mixed with or together
> Maybe my "Chinglish" is not up to the task of translating
>that?
> Paul
> I'm not schooled in "Chinglish" either but
>perhaps this means that you cannot stack this power supply on top of another
>to get a higher voltage out. In other words the ground is not floating.
> Roger
Understand . . . I wonder if I could hire out to this
eBay seller as an editor for their marketing literature.
I read the line you cited and couldn't make any sense
of it. On the other hand, there's another line.
"-Module properties:non-isolated,auto switch
in Booster and step-down voltage,Constant
pressure and current."
It's that "non-isolated" thing that sticks. A strong
anecdotal point is the arrangement of terminals . . .
Emacs!
The IN- and VO- are immediately adjacent which
offers a probability that they are common to each
other on the ECB.
My bet is that this is an example of the common
buck down converter but with some additional
electronics that offers BOTH regulation set
points for both current and voltage.
I'm thinking about ordering one just to
check it out. It appears to offer a lot of
performance for the money.
Bob . . .
Message 4
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Subject: | Fuses instead of breakers |
I really like the idea of using fuses rather than breakers. The ATC
style fuses look like a excellent product.
However, I cannot find any "slo-blow" versions. Do they exist ? How
do I decide on the size of the fuse when manufacturers of products
recommend a breaker or slow-blo fuse ?
For example, the Lightspeed ignition instructions suggest a 5A breaker
with an 18AWG wire. So a 7.5A or 10A fuse could easily be used with
that wire.
An ATC fuse typically blows at 125% of rating within a second, much
faster than a breaker. How do I know what the peak current is on
various devices to know that there will not be a nuisance trip (a
really bad thing for electronic ignitions) with a fast blow fuse ?
Jeff Page
Dream Aircraft Tundra #10
Message 5
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Subject: | Re: Fuses instead of breakers |
At 01:16 PM 1/24/2012, you wrote:
I really like the idea of using fuses rather than breakers. The ATC
style fuses look like a excellent product.
They are . . .
However, I cannot find any "slo-blow" versions. Do they exist ? How
do I decide on the size of the fuse when manufacturers of products
recommend a breaker or slow-blo fuse ?
Excellent question. It's not always clear to me why
any given installation instruction calls for a "slow-blow"
fuse. WAAaayyy back when, one could purchase fuses for a
given current rating that offered different time constants.
In automobiles I've found that many fuses are way 'oversized'
to the task while still appropriate to protection of the
wire. I don't think there are any fuses in my mini-van under
10A and most are over 10A.
For example, the Lightspeed ignition instructions suggest a 5A breaker
with an 18AWG wire. So a 7.5A or 10A fuse could easily be used with
that wire.
The Lightspeed ignition draws about 2.8A max (full increase
RPM and highest operating temperature) so a 5A fuse is
quite adequate to the load. Heavier wire is sometimes called
out just for mechanical robustness even when the current levels
are low. I think I heard one ol' greybeard at Beech speak
to a policy of "no wires under 20AWG in the engine compartment."
Magneto's were wired with 18AWG shielded even tho much smaller
wire would have provided proper electrical function.
An ATC fuse typically blows at 125% of rating within a second, much
faster than a breaker. How do I know what the peak current is on
various devices to know that there will not be a nuisance trip (a
really bad thing for electronic ignitions) with a fast blow fuse ?
There was a rule of thumb years ago for always-hot battery
feeders not to be protected at levels above 5A. But that
rule of thumb got codified later:
---------------------------
Sec. 23.1361 Master switch arrangement.
(a) There must be a master switch arrangement to allow ready disconnection
of each electric power source from power distribution systems, except as
provided in paragraph (b) of this section. The point of disconnection must be
adjacent to the sources controlled by the switch arrangement. If separate
switches are incorporated into the master switch arrangement, a means must be
provided for the switch arrangement to be operated by one hand with a single
movement.
(b) Load circuits may be connected so that they remain energized when the
master switch is open, if the circuits are isolated, or physically shielded,
to prevent their igniting flammable fluids or vapors that might be liberated
by the leakage or rupture of any flammable fluid system; and
(1) The circuits are required for continued operation of the
engine; or
(2) The circuits are protected by circuit protective devices
with a rating
of five amperes or less adjacent to the electric power source.
(3) In addition, two or more circuits installed in accordance with the
requirements of paragraph (b)(2) of this section must not be
used to supply a
load of more than five amperes.
(c) The master switch or its controls must be so installed that the switch
is easily discernible and accessible to a crewmember.
--------------
Now interestingly enough . . . one can do an experiment where
a 5A breaker and a 10A ATC fuse are connected in series. Dead fault
the circuit on a 12v battery and the fuse always blows before the
breaker trips. From this I would deduce that a 5A breaker of the battery
bus which is compliant with the FAR cited above can be replaced by a
10A fuse in the same location and still be satisfy the design goal.
The 10A fuse is faster than a 5A breaker and dumps less energy into
the fault than a the breaker.
High inrush devices are generally limited to motors and incandescent
lamps. For those circuits, fatter fuses and commensurate increases in
wire size are not without reasonable justification.
Input to the Lightspeed ignition has, at most, a filter capacitor
preceding the switchmode power supply. A 5A fuse is fine. But given
the fatter-wire recommendations for installation, then a 7.5 or
10A FUSE PROTECTED feeder can be brought from the battery bus
without insulting design goals for crash safety cited in 23.1361(b)(2)
above.
For all other systems (not critical to keeping the engine running!)
the experiment is low risk. If you get nuisance trips, upsize the
fuse. You need not necessarily upsize the wire too. Keep in mind that
20A through a 22AWG wire will not burn the wire. See:
http://aeroelectric.com/Pictures/Wire/22AWG_20A.pdf
While your concerns are noteworthy, they can be addressed with
a very broad brush applying common sense. If I were building
an airplane today, I'd protect the electronic ignition battery
feeders at 10A and wire with 20AWG wire that still fits in
the smaller pins for fire wall penetration and/or interface to
the electronics. This offers a mechanically and electrically
robust feeder to the ignition that does not argue with crash
safety design goals.
Bob . . .
Message 6
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Subject: | Fuses instead of breakers |
I used a lot of fuses (4 fuse blocks) and about a dozen breakers (for things
that I need/want control of in flight or during maintenance. I like to have
each on it's own circuit. I don't know of any Slo-blo fuses, but there may
be. It may be that you would simply use a higher value fuse. Something
that protects the wire against hard faults.
I was going to use Lightspeed but changed my mind to P-mags partially for
this reason, they are self powered once flying, therefore do not depend on
ship's power for normal operation.
Bevan
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jeff Page
Sent: Tuesday, January 24, 2012 11:16 AM
Subject: AeroElectric-List: Fuses instead of breakers
I really like the idea of using fuses rather than breakers. The ATC style
fuses look like a excellent product.
However, I cannot find any "slo-blow" versions. Do they exist ? How do I
decide on the size of the fuse when manufacturers of products recommend a
breaker or slow-blo fuse ?
For example, the Lightspeed ignition instructions suggest a 5A breaker with
an 18AWG wire. So a 7.5A or 10A fuse could easily be used with that wire.
An ATC fuse typically blows at 125% of rating within a second, much faster
than a breaker. How do I know what the peak current is on various devices
to know that there will not be a nuisance trip (a really bad thing for
electronic ignitions) with a fast blow fuse ?
Jeff Page
Dream Aircraft Tundra #10
Message 7
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Subject: | Antenna Installation Question |
Hi,
Comant instructions for a comm antenna installation says to mount the antenna base
directly to the skin for proper electrical bonding. Makes sense to me. Then
they include a cork gasket with the antenna. Any suggestions?
I was planning to alodine the skin under the antenna base. Should I put dielectric
grease or anything else between the base and the skin?
--------
Clear Skies,
Tom Costanza
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=364738#364738
Message 8
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Subject: | Re: Antenna Installation Question |
On 01/24/2012 06:26 PM, tomcostanza wrote:
> --> AeroElectric-List message posted by: "tomcostanza"<Tom@CostanzaAndAssociates.com>
>
> Hi,
>
> Comant instructions for a comm antenna installation says to mount the antenna
base directly to the skin for proper electrical bonding. Makes sense to me.
Then they include a cork gasket with the antenna. Any suggestions?
>
> I was planning to alodine the skin under the antenna base. Should I put dielectric
grease or anything else between the base and the skin?
>
> --------
> Clear Skies,
> Tom Costanza
There should be contact between the base & the heads of the mounting
screws, and contact inside the fuselage from the screws through the nuts
and lock washers to the inside of the skin. the teeth of the lock
washers should bite through any paint/primer into the surface of the skin.
Charlie
Message 9
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Subject: | Antenna Installation Question |
The cork gasket goes directly under the antenna, between the antenna and the
skin to prevent water from penetrating the skin under the base. The antenna
grounds through the washer and mounting nut inside the skin. This is
important as this is a ground plane for the antenna. Clean off the alodine,
or zinc chromate from inside the skin around where the mounting nut and
washer grip the inside of the skin.
>From here I'm assuming that you have a cloth plane...
Cloth planes usually have a frame structure under the cloth physically
strong enough to hold a com. ant. but you may need to install you own foil
ground plane. If this is your case then make sure your ground plane is well
grounded through the outside of the antenna connector or preferably the
mounting nut.
Small planes generally have their com antenna on top of the plane... away
from landing gear and other parasitic elements like landing gear. Being on
top is adequate to talk with towers and a good location to communicate with
other aircraft. If you expect to fly above FL2.0 you may need a com Ant on
the bottom of your plane to contact ATC.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
tomcostanza
Sent: January 24, 2012 8:57 PM
Subject: AeroElectric-List: Antenna Installation Question
<Tom@CostanzaAndAssociates.com>
Hi,
Comant instructions for a comm antenna installation says to mount the
antenna base directly to the skin for proper electrical bonding. Makes
sense to me. Then they include a cork gasket with the antenna. Any
suggestions?
I was planning to alodine the skin under the antenna base. Should I put
dielectric grease or anything else between the base and the skin?
--------
Clear Skies,
Tom Costanza
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=364738#364738
Message 10
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Subject: | Re: Antenna Installation Question |
> the teeth of the lock washers should bite through any paint/primer into the surface
of the skin.
Thanks Charlie. I know this makes a good D.C. ground, but I'm not sure how well
it grounds at 100+ MHz. Maybe Bob could speak to that.
--------
Clear Skies,
Tom Costanza
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=364763#364763
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Subject: | Re: Grounding - 28 to 12v down-converter |
On 1/24/2012 6:07 AM, ROGER & JEAN CURTIS wrote:
> Note:
> -Input/output negative cannot be mixed with or together
> Maybe my "Chinglish" is not up to the task of translating
> that?
> Paul
> I'm not schooled in "Chinglish" either but
> perhaps this means that you cannot stack this power supply on top of another
> to get a higher voltage out. In other words the ground is not floating.
> Roger
>
Hmmm... takes a lot of creativity to get there, since they're talking
about input/output, not output/output... and they're talking about
negative, not positive/negative. We'll see what Bob's field trial
determines!
Paul
--
Please note my new email address!
millner@me.com
Message 12
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Subject: | Re: Antenna Installation Question |
At 08:36 PM 1/24/2012, you wrote:
><Tom@CostanzaAndAssociates.com>
>
>
> > the teeth of the lock washers should bite through any
> paint/primer into the surface of the skin.
>
>
>Thanks Charlie. I know this makes a good D.C. ground, but I'm not
>sure how well it grounds at 100+ MHz. Maybe Bob could speak to that.
It's nigh on to impossible to get the 'ideal' bond
between antenna base and skin without welding it. Further,
adding a cork gasket under the base puts a 'resilient'
material in the stack-up of parts under 'crush'. See:
http://aeroelectric.com/Pictures/Antenna/Comm_Antenna_Installation.gif
Since all electrical connections MUST come though the mounting
hardware, getting the highest practical make up forces
goes directly to gas-tightness of the connections at
interfaces marked with (*). All this happens within a few
tenths of an inch of the center of each screw. Taking all
the paint off skin under the antenna adds nothing.
I'd pitch the cork. Drill out the base holes to take at least
a #10 screw (if not already that large). Clean the mate up
surfaces marked (*) to bright. Run a thin bead of RTV around the
perimeter of the base before pressing it into place on the aircraft.
Tighten the screws to spec limits. Using grade 8 hardware
will let you get some real, lasting pressure in the joints.
Bob . . .
Bob . . .
Message 13
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Subject: | Re: Fuses instead of breakers |
You could use a breaker for this particular circuit. I haven't thought about electronic
ignitions specifically but I too like fuses over breakers. But convinced
myself to use 4 breakers anyway, 2 for the 2 voltage regulators, 1 for the
AP, and one for the flaps. Not sure I would have used all 4 now that I've
flown it a bit but it made sense to me at the time. So I still have 2 dozen fuses...
Just a thought.
Bil
Sent from my iPad
On Jan 24, 2012, at 2:16 PM, Jeff Page <jpx@qenesis.com> wrote:
>
> I really like the idea of using fuses rather than breakers. The ATC style fuses
look like a excellent product.
>
> However, I cannot find any "slo-blow" versions. Do they exist ? How do I decide
on the size of the fuse when manufacturers of products recommend a breaker
or slow-blo fuse ?
>
> For example, the Lightspeed ignition instructions suggest a 5A breaker with an
18AWG wire. So a 7.5A or 10A fuse could easily be used with that wire.
>
> An ATC fuse typically blows at 125% of rating within a second, much faster than
a breaker. How do I know what the peak current is on various devices to know
that there will not be a nuisance trip (a really bad thing for electronic ignitions)
with a fast blow fuse ?
>
> Jeff Page
> Dream Aircraft Tundra #10
>
>
>
>
>
Message 14
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Subject: | Re: Weak and Static on Transmission |
What kind of engine, if 2-stroke and using a voltage regular what
brand is it, also what brand/model hand held radio are you using? I
have almost the same identical problem.
When I first flying my new home built airplane it was fine, crystal
clear both transmission and receiving. However, something changed,
now I can hardly understand transmissions. I haven't yet been able
to put my finger on what's changed and causing it.
jerryb
At 09:51 AM 1/22/2012, you wrote:
><nuckolls.bob@aeroelectric.com>
>
>At 07:38 AM 1/20/2012, you wrote:
>><bbradburry@bellsouth.net>
>>
>>Well, to further clarify this problem. I seem to be able to hear ok on the
>>ground while taxiing around the airport, but after I leave the airport the
>>reception gets really bad. At first I thought it was a problem with the
>>approach frequency because that is where it would first start up. It was a
>>loud hiss in the headphones so loud that I could not hear ATC. In fact, I
>>have made two NORDO landings as a result on this loud hiss. I sent my radio
>>back to have it checked out and nothing was found. All this trouble is at
>>below 5000 ft and fine weather. I am flying off my 40 hours (22 so far) and
>>am only flying in good weather. These radio problems at a Class C airport
>>have made me afraid to fly. ATC could take some action against me if it
>>continues.
>
> This is the first time I've been aware that you were having
> problems both with hearing and talking. While the ground
> listeners complain of "static" you have described the extraneous
> audio as a "hiss". We may be talking of two different problems.
> I'm having trouble resolving a single noise source that would
> manifest in both what you hear and what is transmitted to the
> ground.
>
> Get a hand-held transceiver and use it to 'probe' around
> the airplane. Use tune the hand-held to an unused frequency,
> open the squelch and open the volume to get a low level of
> no-signal hiss common to all receivers. Then probe around
> the panel mounted goodies and wire harnesses with the
> hand-held's antenna. See if the no-signal hiss changes
> in level with the master switch on versus off. If it does
> change, turn off accessories and/or pull breakers/fuses to
> see if any one accessory produces a noticeable change
> in noise from the hand-held.
>
> You can use the hand-held as an airborne signal quality
> sniffer too. Use a headset with the hand held to listen
> to your own transmitted signals. You may have to take the
> antenna off the hand-held to avoid overloading the hand-held
> receiver. You don't need to talk on the ship's radio, just
> listen to your transmitted signal to characterize the noise.
> Is it the same "hiss" you hear in your received signals?
>
> In any case, carry the hand held to avoid the no-radio
> return to the airport. In fact, having the 'three musketeers
> of dark-panel ops' in your flight bag is good insurance
> for any flights:
>
>www.aeroelectric.com/Pictures/Misc/Failure_Tolerance.pdf
>
> It was also suggested that you try a substitute antenna.
> I've fabricated test antennas that could be taped to the
> top or bottom surface of a wing and coax brought into
> the cockpit through the door gasket or some other pathway.
>
> But using the hand-held to characterize your transmitted
> and received signals personally takes ATC and others
> out of the loop. This is an especially good thing when
> they're unable/unwilling to join the discussion and
> offer their own observations/insights.
>
>
> Bob . . .
>
>
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