Today's Message Index:
----------------------
1. 05:55 AM - Re: Noise Filter for Strobe power and regulator? (Steve Stearns)
2. 08:08 AM - Re: Kitplanes article on an Elegant LED driver (Brantel)
3. 09:44 AM - Re: B+C alternator problem (Robert L. Nuckolls, III)
4. 10:42 AM - Re: Re: Kitplanes article on an Elegant LED driver (Robert L. Nuckolls, III)
5. 10:42 AM - Re: Noise Filter for Strobe power and regulator? (Robert L. Nuckolls, III)
6. 11:17 AM - Project Almost Done - Cleaning House... (Don Honabach)
7. 02:11 PM - Re: Switch problem (Gary Lineberry)
Message 1
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Subject: | Re: Noise Filter for Strobe power and regulator? |
>
> ** >Bob,
> >Regarding my interest in a noise filter for my strobe:
> >>**
> >> Now does noise from the strobe manifest itself
> >> in your system?
> >>
> >> **
> >I was told it was audible via the intercom and the previous owner had
> >glued (literally) a massive aluminum electrolytic to the top of the case
> >(the size of a tall drinking glass) "which helped" (as I remember being
> >told). I'm redoing the wiring from scratch and it's possible that
> >elimination of a previously existing big radio/intercom power feed loop
> >will have taken care of the problem but it seems prudent to put some
> >filtering in to replace the overly large cap.
> >
> >My goal is to put in something "reasonable" and, with luck, not have
> >anything to chase down in this area when I power everything back up again
> >after the rewiring.
>
> This is a LongEz? Where is the strobe supply mounted
> and how is it grounded? Do you have a single point
> ground system? Where are the microphone and headset
> jacks grounded?
> **
It's a LongEZ, I'm redoing the wiring (all of it..., In fact there is no
wire left in the airframe right now, but I made a full set of
"as-builts" before I ripped it all out) as I didn't like some things I
found. The first issue that I think could have been a big contributor
for strobe noise is that the power and ground for the radio and intercom
stack (which was one breaker for all, but will be separate fuses) ran
different directions from the radio with the ground running forward to
the battery while the power ran backward on the left side, crossed over
to the right side through the pilot headrest and then forward to the
switch panel in the right strake before continuing forward to the
battery. This left a huge inductive loop for noise pickup. This will
be fixed. The strobe power was mounted under the wing spar in the "hell
hole" and was grounded both directly to the firewall (via case mounting)
and through a power cable that ran up to the switch panel which there
had a separate ground back to the firewall. This put the the strobe in
the middle of one of the ground loops (all of which will be
eliminated). The radio, intercom and instruments, and this is worth
something..., were at least on a separate non-looped ground direct to
the battery. At the jacks, the mic and headphone jacks were only
grounded to each other and to a ground wire and the shields on a closely
paired pair of shielded cables back to the avionics harness. There was
technically a ground loop in the two shields but not an egregious one as
there was no area within the loop (but it will be fixed none-the-less).
From your questions I'm inferring that noise problems with a Whelen
Strobe supply is not a given. And I'm now expecting you might suggest
that since I'm rewiring and eliminating an obvious noise propagation
path (that from the nice open power supply ground-loop to the nice open
radio power path loop...) and possible other less-obvious ones (and
hopefully avoiding any of my own design) perhaps I should wait on the
noise filter until I determine if I still have a problem.
(In student mode...) How'd I do?
Steve Stearns
Boulder/Longmont, Colorado
CSA,EAA,IAC,AOPA,PE,ARRL,BARC (but ignorant none-the-less)
Restoring (since 1/07): N45FC O235 Longeze Cothern/Friling CF1 (~1000 Hrs)
Flying (since 9/86): N43732 A65 Taylorcraft BC12D
Message 2
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Subject: | Re: Kitplanes article on an Elegant LED driver |
Bob,
The driver shipped direct to you on Tuesday. Please let me know when you get it.
DO NOT ARCHIVE
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 2519#202519
Message 3
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Subject: | Re: B+C alternator problem |
>
> Call B&C at 316-283-8000 and see if they're interested
> in updating your LR-3 with respect to noise immunity.
> If push comes to shove, I can modify it for you but
> let's see what they say first.
>
> Bob . . .
>
>Bob -
>Talked to Bill at B+C this afternoon and he wasn't too convinced the LR-3B
>needed much of an upgrade. He says there is a LR-3C being built now and I
>get the idea it has some transient type improvements built in. His
>suggestion was to monitor the low voltage light to see under which
>conditions it comes on. I don't think I can get it to trip when I
>want. I am suspecting it might not be a consistent cause i.e. the dreaded
>intermittent type of thing. But, I now know enough about the location of
>components in my particular system to troubleshoot if I knew where to
>start. The only thing I have done is put a 20 amp fuse in the field
>location. I haven't flown it yet this way. JBB
This tends to confirm my suspicion that B&C has
probably not replaced departed technical staff that
used to support this and other products . . .
It's true that the "C" version was crafted to offset the
effects of an extra-ordinary (outside the Mil-Std-704
envelope) noise situation on the G36 Bonanza. It's
also true that your particular installation may be
generating some un-anticipated stress that upsets
the ov protection.
I should point out here . . . AGAIN . . . that this
situation is not unique to the so-called "crowbar"
shutdown philosophy. It's a situation driven by the
dynamics of circuitry that watches for an ov condition
and makes a Let-Run/Shut-Down decision. It's a system
design and integration problem that must be solved
irrespective of the designer's choice for shut-down
philosophy. I.e, anyone's OV protection scheme can
be similarly "spoofed" into an unnecessary shutdown
event.
My sense is that B&C is hopeful of keeping this prolem
out of their shops . . . so let's do this.
The upstream field supply protection should be a 5A
breaker. If there's a "fusible" function upstream
of the breaker, make it a 24AWG fusible link. Let's
get the unit-fuse out of the system. The breaker
should be mounted within reach of the pilot.
Let's do some flying and see if you can identify
the antagonist condition. By the way, I'm assuming
you DO have a single point ground behind the panel
for all the electro-whizzies? Let's conduct some
experiments to see if the noise source can
be deduced.
If push comes to shove, you can mail me your regulator
and I'll modify it here. I think I recall all the things
we did to them . . . but it's been 7-10 years ago.
Bob . . .
Message 4
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Subject: | Re: Kitplanes article on an Elegant LED driver |
At 08:04 AM 9/4/2008 -0700, you wrote:
>
>Bob,
>
>The driver shipped direct to you on Tuesday. Please let me know when you
>get it.
>
>DO NOT ARCHIVE
Very well. the inductors got here today. The boards
will be here tomorrow.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 5
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Subject: | Re: Noise Filter for Strobe power and regulator? |
>>
>> This is a LongEz? Where is the strobe supply mounted
>> and how is it grounded? Do you have a single point
>> ground system? Where are the microphone and headset
>> jacks grounded?
>>**
>It's a LongEZ, I'm redoing the wiring (all of it..., In fact there is no
>wire left in the airframe right now, but I made a full set of "as-builts"
>before I ripped it all out) as I didn't like some things I found. The
>first issue that I think could have been a big contributor for strobe
>noise is that the power and ground for the radio and intercom stack (which
>was one breaker for all, but will be separate fuses) ran different
>directions from the radio with the ground running forward to the battery
>while the power ran backward on the left side, crossed over to the right
>side through the pilot headrest and then forward to the switch panel in
>the right strake before continuing forward to the battery. This left a
>huge inductive loop for noise pickup. This will be fixed. The strobe
>power was mounted under the wing spar in the "hell hole" and was grounded
>both directly to the firewall (via case mounting) and through a power
>cable that ran up to the switch panel which there had a separate ground
>back to the firewall. This put the the strobe in the middle of one of the
>ground loops (all of which will be eliminated). The radio, intercom and
>instruments, and this is worth something..., were at least on a separate
>non-looped ground direct to the battery. At the jacks, the mic and
>headphone jacks were only grounded to each other and to a ground wire and
>the shields on a closely paired pair of shielded cables back to the
>avionics harness. There was technically a ground loop in the two shields
>but not an egregious one as there was no area within the loop (but it will
>be fixed none-the-less).
>
> From your questions I'm inferring that noise problems with a Whelen
> Strobe supply is not a given. And I'm now expecting you might suggest
> that since I'm rewiring and eliminating an obvious noise propagation path
> (that from the nice open power supply ground-loop to the nice open radio
> power path loop...) and possible other less-obvious ones (and hopefully
> avoiding any of my own design) perhaps I should wait on the noise filter
> until I determine if I still have a problem.
There are tens of thousands of strobe systems flying
with no or (at least acceptably low) noise issues. So
yes, the need for filtering is not a given. Further,
the need to ADD filtering gives pause to wonder if
there are other deficiencies in the system integration
that drives the need for a band-aid filter later.
I've never had to "fix" a regulator installation
to mitigate a noise issue.
My suggestion is that you continue your clean-up
tasks with a goal of crafting a system that is as
tolerant of the strobe as the thousands of installations
cited above. After all, these ARE DO-160 qualified devices . . .
if they don't live happily in any given system, it's
likely that design deficiencies exist in the system.
The road to Nirvana starts at the common point ground
where electro-whizzies, battery(-) and a FATwire-to-
crankcase all come together. There can be other
ground wire concentration points but given the size
of this airplane and the narrow, tandem cockpit
width, the one-ground-does-it-all approach is doable
and attractive.
Lack of shielding (or inauspicious use of shielding)
is almost NEVER the source of a noise problem. Most of
our airplanes have much more shielded wire than is
necessary . . .
>(In student mode...) How'd I do?
The fact that you're sifting the sand with us
on such matters bodes well for success with
understanding.
Bob . . .
Message 6
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Subject: | Project Almost Done - Cleaning House... |
After over 10 years I'm almost done with my Zodiac 601HDS project (yes,
HDS) and I'm cleaning out/selling off the extras to make a little peace
in the family...
I've put up 2 Electric Gyros Indicators on eBay if anyone is interested:
RCA15AK-1 14V Electric Directional Gyro (Lighted)
http://tinyurl.com/6n66vm
RCA26AK-1 14V Electric Attitude Indicator Gyro (Lighted)
http://tinyurl.com/5nnfuu
Both are brand new, have zero hours and were bought at R.C. Allen Booth
at Oshkosh.
Don Honabach
Tempe, AZ
601HDS
Message 7
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Subject: | Re: Switch problem |
Interestingly I have had almost the same problem. With a little over 200
hours on the aircraft my Whelen strobe system stopped working. It did not
open the 10A fuse, but when switched on the strobes would flash for about 10
seconds and then stop. I was thinking that it was a problem with the Whelen
unit but it is in a very difficult place to get to in my RV8 (under the
floor) so I haven't yet gone to the effort to take up the floor to check it
out. I looked at the fuse block and things looked good. Until I read this
thread I didn't think about looking at the switch...my mistake. When I
examined the switch today I discovered that the blue insulation on the
Fast-On connectors had darkened considerably, indicating that they have been
getting hot. They are still firmly attached to the wire but it appears
there is an internal problem in the switch that is causing excessive heat.
It is the B&C 1-3 switch referenced in this discussion. I have just ordered
a few of the Honeywell switches from Digi-Key and will replace it with one
of those. I don't know what the actual current draw on the circuit is, but
I have a 10A fuse that has not opened, so I would think that the B&C switch
should handle it. On the other hand, it appears that there is some other
factor afoot here in the strobe circuit that the 1-3 does not like. We'll
see how the Honeywell switch handles it.
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