Today's Message Index:
----------------------
1. 03:37 AM - Re: GROUND LOOPS (tomcostanza)
2. 08:59 AM - Re: Re: GROUND LOOPS (Robert L. Nuckolls, III)
3. 09:21 AM - Re: CdS Photocell Holder/Fixture (Robert L. Nuckolls, III)
4. 09:56 AM - Re: CdS Photocell Holder/Fixture (David E. Nelson)
5. 10:35 AM - Re: New Z-8 drawing (jonlaury)
6. 04:31 PM - Re: Re: New Z-8 drawing (Robert L. Nuckolls, III)
7. 11:21 PM - Re: New Z-8 drawing (jonlaury)
Message 1
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| Subject: | Re: GROUND LOOPS |
Hey Bob,
Could you explain, or point me to an explanation of, what kinds of things qualify
as antagonists? From your reply to this question, it's clear I don't understand.
--------
Clear Skies,
Tom Costanza
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=308337#308337
Message 2
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| Subject: | Re: GROUND LOOPS |
At 05:33 AM 8/11/2010, you wrote:
><Tom@CostanzaAndAssociates.com>
>
>Hey Bob,
>
>Could you explain, or point me to an explanation of, what kinds of
>things qualify as antagonists? From your reply to this question,
>it's clear I don't understand.
99% of the time, antagonists are generally those devices
which generate noise in the form of electrical "wiggles".
These include radios that are poorly shielded. Motors. Strobe
power supplies. Certainly alternators. Instruments with
poorly shielded/filtered LCD power supplies. Switchmode
power adapters common to many hand-held devices including
GPS, cellphones, PDA, MP3 players, etc.
There are some instances where non-wigglers like incandescent
landing lights, pitot heaters, nav lights, etc can influence
other systems . . . like the example I gave for poorly grounded
engine instruments being affected by variations in current
flowing through a crankcase-to-battery ground conductor.
Even if the device IS a potential antagonist (like a strobe
power supply), not carrying it's power ground back to a
single point does not represent a risk as long as POTENTIAL
victims do not share the same ground path.
This is discussed in some detail in chapter 16 of the
'Connection. In that work I attempt to explain that
potential victims and antagonists can and do coexist
in airplanes as long as you make sure there is no
PROPAGATION mode for the conveyance of malicious
energy between them. Breaking of propagation pathways
includes but is not limited to certain kinds of shielding,
filters, modification of design to reduce noise and
installation practices to eliminate shared ground paths.
I can tell you that airplanes like the Beechjet have
HUGE potential antagonists, and exceedingly vulnerable
victims that for the most part have worked side by side
for a long time. This is a design goal for every TC
aircraft and should be a goal for OBAM aircraft as well.
The vast majority of your potential victims reside on
the panel. Judicious attention to grounding at the
panel will greatly reduce potential for problems
no matter how your ground other accessories scattered
about the airplane.
Bob . . .
Message 3
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| Subject: | Re: CdS Photocell Holder/Fixture |
Hi All,
I'm trying to locate a holder/fixture for a CdS photocell
(http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PDV-P9203-ND)
so that I can mount one on the panel. Google, Mouser, and Digikey
searches just don't seem to be working for me.
Thank you,
/\/elson
These devices are members of the family
of parts intended to be components of a
larger assembly. I don't recall ever seeing
a "holder" for such devices. Building a holder
is not difficult.
Poke around in your local electronics supply
houses including Radio Shack. You can probably
find an existing product like . . .
Emacs!
that can be stripped of its innards and
then modified to your purposes with the
help of a little wire, solder and epoxy.
Bob . . .
Message 4
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| Subject: | Re: CdS Photocell Holder/Fixture |
Hi Bob,
I've seen some LED fixtures that just might fit the bill as you describe.
Vi!
Thank you,
/\/elson
~~ Lately my memory seems to be like a steel trap .... without any spring. ~~
On Wed, 11 Aug 2010, Robert L. Nuckolls, III wrote:
>
>
> Hi All,
>
> I'm trying to locate a holder/fixture for a CdS photocell ( http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PDV-P9203-ND ) so that I can mount one on the panel. Google,
> Mouser, and Digikey searches just don't seem to be working for me.
>
> Thank you,
> /\/elson
>
> These devices are members of the family
> of parts intended to be components of a
> larger assembly. I don't recall ever seeing
> a "holder" for such devices. Building a holder
> is not difficult.
>
> Poke around in your local electronics supply
> houses including Radio Shack. You can probably
> find an existing product like . . .
>
> Emacs!
>
> that can be stripped of its innards and
> then modified to your purposes with the
> help of a little wire, solder and epoxy.
>
> Bob . . .
>
>
>
Message 5
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| Subject: | Re: New Z-8 drawing |
> Okay, we can press a 9024 into service as dual
> LV warning only. Another 9024 would take care
> of lv warning for both battery and main busses
> PLUS ov protection for the S/B alternator.
>
I'm a little confused about the need for two 9024's if one can give LV indication
for Batt and Main busses and OV protection from the stby alt.
And would the OV protection extend to the shared contactor (stby alt/GPJ) for the
ground power jack as in the attached?
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=308387#308387
Attachments:
http://forums.matronics.com//files/z8_w_sb_alt_gpj_conceptual__214.pdf
Message 6
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| Subject: | Re: New Z-8 drawing |
>
>I'm a little confused about the need for two 9024's if one can give
>LV indication for Batt and Main busses and OV protection from the stby alt.
Oops, I had a brain-f@#t and was running the
hampster wheel on another system. Got too many
irons in the fire.
I'm still stirring the pot on how to get the
s/b alternator b-lead contactor to retain
ground power reverse polarity and ov protection.
The architecture you've illustrated agrees with
my best recipe for the moment. Separate ov protection
for the ground power contactor (probably crowbar)
and another for s/b alternator field (probably
9024 driving a relay so you don't need a circuit
breaker).
>And would the OV protection extend to the shared contactor (stby
>alt/GPJ) for the ground power jack as in the attached?
We need to think about how the crowbar ov
module interacts with the 9024 ov protection.
We don't want the contactor to open before the
ov relay gets tripped. I think we'll want to wire
things so that the crowbar module is effective only
while the ground power control switch/breaker is
closed. I.e. move the black wire to the cathode
end of the diode in the ground power control lead.
Bob . . .
Message 7
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| Subject: | Re: New Z-8 drawing |
> Oops, I had a brain-f@#t and was running the
> hampster wheel on another system. Got too many
> irons in the fire.
No worries and I know that I speak for all of us on this forum; it is simply astounding
that you manage to participate here as much as you do AND keep your day
job.
> I think we'll want to wire
> things so that the crowbar module is effective only
> while the ground power control switch/breaker is
> closed. I.e. move the black wire to the cathode
> end of the diode in the ground power control lead.
>
OK, that's done in the attached. I quarantined the 9005 module for now until OV
protection and LV monitoring gets ironed out. With 9024 control of the SB alt,
I deleted the fuselink from the Batt bus in favor of a 5a fuse.
Re the Main bus, with an LR3 in there, it seems that the main bus is taken care
of and it's not necessary to integrate the SB alt 9024 voltage monitoring into
the main bus. Can a 9024 now focus solely on the SB alt and battery bus?
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=308465#308465
Attachments:
http://forums.matronics.com//files/z8_w_sb_alt_gpj_conceptual__345.pdf
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