Today's Message Index:
----------------------
1. 03:00 AM - Crowbar OV module part (Phil)
2. 04:30 AM - Re: HLMP-2685 multi-LEDs off LR3C (James Kilford)
3. 06:51 AM - Re: Crowbar OV module part (Robert L. Nuckolls, III)
4. 06:56 AM - Re: Lithium backup power (Robert L. Nuckolls, III)
5. 07:20 PM - intermittent transponder mystery solved (Bill Boyd)
6. 10:51 PM - Re: intermittent transponder mystery solved (David LLoyd)
Message 1
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Subject: | Crowbar OV module part |
Bob: The part listed as "MBS4991" is no longer carried by Digi-Key.
Mouser lists a possible replacement as a silicon bi-lateral switch by
NTE as their part NTE6403. Is this the correct type item? Or is that
device something else?
Need to build 2 OV modules for my electrically dependent, dual
alternator project.
Phil
RV-10 w/ Mazda 20B rotary engine in IL
Message 2
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Subject: | Re: HLMP-2685 multi-LEDs off LR3C |
Bob,
That's great, thank you. It gives me a good place from which to experiment.
James
On Thu, Apr 8, 2010 at 2:04 PM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
> <nuckolls.bob@aeroelectric.com>
>
>
>>
>>
>> http://parts.digikey.com/1/parts/681506-led-lt-bar-hi-eff-red-8led-dip-hlmp2685.html
>>
>> I'd like to hook one of these to the LR3C regulator instead of the
>> supplied filament lamp, so that it can go into the annunciator panel
>> too.
>>
>> I've been trying to trace a schematic of Bob's, which I'm sure I've
>> seen, of how to use an LED instead of a filament lamp with the LR3C,
>> as a starting point. I can't find it, and the resistor values would
>> be different in any case, so can anyone throw any light on to how to
>> use one of these 8-LED devices with the LR3C?
>
> The schematic I published is at:
>
> http://aeroelectric.com/Pictures/Schematics/LR3_LV_Led_1.jpg
>
> Your application will take some experimentation.
> You can try paralleling all the LEDs and seeing how
> well you can excite the array and still have uniform
> illumination. You may find that you need to treat
> them as separate LEDs.
>
> Just be aware that LR3 lamp driver is never completely
> "OFF". The off current is too low to get any light
> from a bulb but it will cause an LED to glow at a
> reduced intensity. Hence the paralleling resistor to
> get the LED to mimic a lamp more closely.
>
> Bob . . .
>
>
Message 3
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Subject: | Re: Crowbar OV module part |
At 04:57 AM 4/11/2010, you wrote:
>
>Bob: The part listed as "MBS4991" is no longer carried by Digi-Key.
>Mouser lists a possible replacement as a silicon bi-lateral switch
>by NTE as their part NTE6403. Is this the correct type item? Or is
>that device something else?
>
> Need to build 2 OV modules for my electrically dependent, dual
> alternator project.
Those devices have been out of production for
many years. We purchased one-time-lifetime-buys
to keep our production needs at B&C/AEC going
but developed the 2-transistor synthetic trigger
diode version illustrated in the DIY data package
for when they finally run out.
Suggest you consider that version for your project.
I'm aware of no suitable replacements for the MBS4991/4992
component.
Bob . . .
Message 4
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Subject: | Re: Lithium backup power |
At 08:46 PM 4/9/2010, you wrote:
>Bob,
>You've probably already heard about this. Any comments?
>
>The huge advancements in lithium battery technology that have
>improved consumer products ranging from cell phones and laptop
>computers to electric cars will soon arrive in aircraft.
>Mid-Continent Instruments recently certified an emergency power
>supply known as the MD835, which is designed to keep electric
>attitude indicators and other critical avionics working when the
>aircraft systems that power them fail.
>
>Stan Sutterfield
>
Sure. Li-Ion has been taking hold in emergency back-up
batteries for some years. They're particularly well
suited to situations that do not call for humongous
discharge (cranking) and charge (dual 600A generators)
currents.
A couple years ago I evaluated the 7V Li-Ion cartridges
from one of the famous hand-tool manufacturers . . . pretty
good batteries but still a pain in the arse for doing
a graceful system integration.
My personal design goals will continue to move forward
with the notion that it's better to build a failure-tolerant
system than patch on emergency back-up band-aids. The
artfully crafted, maintained and operated system will not
experience an emergency.
Bob . . .
Message 5
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Subject: | intermittent transponder mystery solved |
I finally ran to ground my transponder intermittent that has been plaguing
me for years! My set-up is a Garmin GTX 320 in a tray that formerly housed
a Narco AT-150, using Garmin's plug-and-play adapter to fit between the two.
The first time it crapped-out, I sent the transponder back to Garmin: $250
bench fee to be told the box is fine. Worked fine for awhile after that.
Then it started becoming intermittent - the interrogation light would
flicker normally at the start of a cross-country, and ATC could give me VFR
advisory service, but often by the time I got to the destination I was only
showing as a primary target on radar.
I limped along like this for awhile, but the prospect of having to enter the
Orlando mode C veil next week with "known issues" motivated me to try again.
I started with what has worked before - removing the transponder and
adapter tray, spraying every connection with contact cleaner and
reassembling it all. Well, that worked for a few seconds and then it quit
again, so I got out the continuity checker and started checking the RF path
for opens and shorts. The meter showed an open on the coax center conductor
when I wiggled it in the back of thel Narco tray. Put the innards back in,
and sure enough, if I held the coax a certain way, I saw interrogation
flashes; if I let go, it stopped. Now all I need is for the pax to reach
under the panel and hold the coax the whole trip. Not happening.
The BNC jack on the transponder itself looked good; the male mating plug on
the front side of the adapter looked good - no bent pin. The female jack in
the back of the Garmin-to-Narco adapter looked good. There is a small
length of RG-184-type teflon coax inside the adapter, but it is totally
protected inside the chassis and is under no mechanical strain, and it's new
Garmin manufacture, so the problem can't be there <hold that thought> so the
fault must be in that ancient RG-58 pigtail that came with the Narco tray
and was probably soldered in the 1950's. But the continuity checker showed
no opens or shorts no matter how I wiggled it on the bench, and its coax
shield is well-crimped and fully strain-relieved. Maybe the male pin on the
end of that pigtail, the one that's captive in the back of the tray, is
worn/undersize. So I added a thin layer of solder to the gold pin and
pressed it back into the fitting on the Garmin adapter tray - still showed
an intermittent open when I wiggled it! @#$%!
At this point, I noticed that as I twisted the jack into the plug, the shell
of the Garmin female (the barrel) would move with it. That's not supposed
to happen. In fact, the entire guts of the Garmin female fitting is threaded
into its mounting flange, and since it is not secured or safetied in any way
(and was doubtless under-torqued at assembly), movement of the male coax
pigtail on the outside of the tray eventually broke the BNC solder
connection inside the Garmin adapter. I re-threaded the outer shell of the
Garmin adapter's female connector with red LocTite and re-soldered the
mini-coax to it. Problem fixed - hopefully for good!
Moral of the story: never assume that a factory avionics assembly is
properly done, or that a wire that "can't possibly" move/break hasn't done
just that. I only wish that there was some lifetime warranty where the
Garmin would comp me for the time and aggravation this has caused.
I'm attaching pictures that show the adapter tray, the fitting as it comes
apart but isn't supposed to, and how it broke the solder joint internally.
The last one shows the guts of the BNC fitting completely unscrewed from
its mounting flange and the coax just hanging there. May this never happen
to you! :-) If it does, remember to question everything you're assuming.
I'm gonna feel bad if the pictures don't upload - never done that on
Matronics list before.
-Bill B. / "Stormy" RV-6A
Message 6
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Subject: | Re: intermittent transponder mystery solved |
Bill,
If you reach the right service engineer at Garmin, repeat the story, I
am sure that they would be happy to compensate you and also return the
$250 left on their table. I have had issues with Garmin several times
in the past, and when the story was told, they were gracious about
working with me. Unless things have changed at Garmin, I would take
your service problem back to them. They may have an assembly problem or
Q/C problem and would want to know about it...... Shouldn't matter if
the unit is out of warranty....
If you don't have luck with your first try at the refund, review their
management team via the web and write the key guy a detailed letter....
he will make it happen....
David
-------------------------------------------------------------------------
-------
----- Original Message -----
From: Bill Boyd
To: rvsoutheast-list@matronics.com ; aeroelectric-list@matronics.com
Sent: Sunday, April 11, 2010 7:15 PM
Subject: AeroElectric-List: intermittent transponder mystery solved
I finally ran to ground my transponder intermittent that has been
plaguing me for years! My set-up is a Garmin GTX 320 in a tray that
formerly housed a Narco AT-150, using Garmin's plug-and-play adapter to
fit between the two. The first time it crapped-out, I sent the
transponder back to Garmin: $250 bench fee to be told the box is fine.
Worked fine for awhile after that. Then it started becoming
intermittent - the interrogation light would flicker normally at the
start of a cross-country, and ATC could give me VFR advisory service,
but often by the time I got to the destination I was only showing as a
primary target on radar.
I limped along like this for awhile, but the prospect of having to
enter the Orlando mode C veil next week with "known issues" motivated me
to try again. I started with what has worked before - removing the
transponder and adapter tray, spraying every connection with contact
cleaner and reassembling it all. Well, that worked for a few seconds
and then it quit again, so I got out the continuity checker and started
checking the RF path for opens and shorts. The meter showed an open on
the coax center conductor when I wiggled it in the back of thel Narco
tray. Put the innards back in, and sure enough, if I held the coax a
certain way, I saw interrogation flashes; if I let go, it stopped. Now
all I need is for the pax to reach under the panel and hold the coax the
whole trip. Not happening.
The BNC jack on the transponder itself looked good; the male mating
plug on the front side of the adapter looked good - no bent pin. The
female jack in the back of the Garmin-to-Narco adapter looked good.
There is a small length of RG-184-type teflon coax inside the adapter,
but it is totally protected inside the chassis and is under no
mechanical strain, and it's new Garmin manufacture, so the problem can't
be there <hold that thought> so the fault must be in that ancient RG-58
pigtail that came with the Narco tray and was probably soldered in the
1950's. But the continuity checker showed no opens or shorts no matter
how I wiggled it on the bench, and its coax shield is well-crimped and
fully strain-relieved. Maybe the male pin on the end of that pigtail,
the one that's captive in the back of the tray, is worn/undersize. So I
added a thin layer of solder to the gold pin and pressed it back into
the fitting on the Garmin adapter tray - still showed an intermittent
open when I wiggled it! @#$%!
At this point, I noticed that as I twisted the jack into the plug, the
shell of the Garmin female (the barrel) would move with it. That's not
supposed to happen. In fact, the entire guts of the Garmin female
fitting is threaded into its mounting flange, and since it is not
secured or safetied in any way (and was doubtless under-torqued at
assembly), movement of the male coax pigtail on the outside of the tray
eventually broke the BNC solder connection inside the Garmin adapter. I
re-threaded the outer shell of the Garmin adapter's female connector
with red LocTite and re-soldered the mini-coax to it. Problem fixed -
hopefully for good!
Moral of the story: never assume that a factory avionics assembly is
properly done, or that a wire that "can't possibly" move/break hasn't
done just that. I only wish that there was some lifetime warranty where
the Garmin would comp me for the time and aggravation this has caused.
I'm attaching pictures that show the adapter tray, the fitting as it
comes apart but isn't supposed to, and how it broke the solder joint
internally. The last one shows the guts of the BNC fitting completely
unscrewed from its mounting flange and the coax just hanging there. May
this never happen to you! :-) If it does, remember to question
everything you're assuming.
I'm gonna feel bad if the pictures don't upload - never done that on
Matronics list before.
-Bill B. / "Stormy" RV-6A
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