Today's Message Index:
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1. 06:28 AM - Re: LED Ghosting (eschlanser)
2. 06:52 AM - Re: LED Ghosting (Dennis Johnson)
3. 06:56 AM - Re: Re: LED Ghosting (Sprocket)
4. 07:30 AM - Fw: Re: LED Ghosting (Roger & Jean)
5. 07:51 AM - Re: Fw: Re: LED Ghosting (Robert L. Nuckolls, III)
6. 08:02 AM - Re: Re: LED Ghosting (Sprocket)
7. 08:18 AM - Re: Fw: Re: LED Ghosting (Roger & Jean)
8. 08:51 AM - Re: Re: LED Ghosting (Robert L. Nuckolls, III)
9. 09:10 AM - Re: Re: LED Ghosting (Robert L. Nuckolls, III)
10. 12:54 PM - Re: LED Ghosting (donjohnston)
11. 01:04 PM - Re: LED Ghosting (donjohnston)
12. 03:11 PM - Re: Off Delay Cabin Light (Eric M. Jones)
13. 04:05 PM - Re: Re: Off Delay Cabin Light (R&J. Curtis)
14. 04:10 PM - Re: Re: LED Ghosting (Robert L. Nuckolls, III)
15. 04:21 PM - Re: Off Delay Cabin Light (user9253)
Message 1
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Subject: | Re: LED Ghosting |
donjohnston wrote:
>
>
> "The engine analyzer people said it was designed for incandescent... "
Here's a simple solution. Use an incandescent bulb such as this: http://tinyurl.com/kw8usxc
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425076#425076
Message 2
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Subject: | Re: LED Ghosting |
I don't remember specifically which of your instruments has the ghosting
problem. I'll tell you my story, which may or may not be relevant, but
it may help others with a similar situation as mine.
When I first powered up my instrument panel, the red warning light for
my Grand Rapids EIS engine monitor glowed very dimly when the panel was
powered up but the engine monitor was turned off. Ghosting went away
when I turned the engine monitor on. Like you, I had replaced an
incandescent light with an LED. On the bench, the ghosting seemed like
a problem.
However, I focused on other, bigger, problems and never got around to
fixing the ghosting problem. By the time I completed my flight test
phase, I understood that the ghosting was not a problem at all and maybe
even a benefit.
I turn the engine monitor on before engine start and leave it on until
after engine shutdown. Since ghosting only occurs when the master
switch is on and the engine monitor is off, I never see ghosting because
the engine monitor is normally on whenever the master switch is on. I
now consider ghosting, if I ever see it, to be a warning that I've
forgotten to turn the engine monitor on. "It's not a bug, it's a
feature."
Good luck,
Dennis
Message 3
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Subject: | Re: LED Ghosting |
.....so the relay option is looking pretty good right about now. As I mentioned,
there is the simple brute force relay method, then the more complicated 'elegant'
method.... Elegance is elusive.
Vern
===================================================
Sent from my iThing. It is responsible for all gramma and typo terrors.
> On Jun 18, 2014, at 6:27 AM, "eschlanser" <eschlanser@yahoo.com> wrote:
>
>
>
> donjohnston wrote:
>>
>>
>> "The engine analyzer people said it was designed for incandescent... "
>
>
> Here's a simple solution. Use an incandescent bulb such as this: http://tinyurl.com/kw8usxc
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=425076#425076
>
>
>
>
>
>
>
>
>
>
Message 4
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Subject: | Re: LED Ghosting |
I submitted this a couple of days ago and it seemed to be ignored. Does
anyone know why this very simple method would not work??
Perhaps you could use a zener with a voltage just slitely
higher than the open circuit off voltage output. Put that in
series with the LED, to block the small output, and reduce
the series resistor to bring the brightness up.
Roger
Message 5
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Subject: | Re: LED Ghosting |
At 09:29 AM 6/18/2014, you wrote:
>I submitted this a couple of days ago and it seemed to be
>ignored. Does anyone know why this very simple method would not work??
>
> Perhaps you could use a zener with a voltage just slitely
> higher than the open circuit off voltage output. Put that in
> series with the LED, to block the small output, and reduce
> the series resistor to bring the brightness up.
Not sure what you're suggesting . . . can
you offer a schematic along with some
description of where the voltage drops are
expected and of what magnitude?
Bob . . .
Message 6
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Subject: | Re: LED Ghosting |
Dimming wouldn't work very well with an in series zener.
Vern
==========================
==========================
Sent from my iThing. It is responsible for all gramma and typo terrors.
> On Jun 18, 2014, at 7:29 AM, "Roger & Jean" <rnjcurtis@charter.net> wrote:
>
> I submitted this a couple of days ago and it seemed to be ignored. Does a
nyone know why this very simple method would not work??
>
> Perhaps you could use a zener with a voltage just slitely
> higher than the open circuit off voltage output. Put that in
> series with the LED, to block the small output, and reduce
> the series resistor to bring the brightness up.
>
> Roger
>
>
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D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
Message 7
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Subject: | Re: LED Ghosting |
Perhaps you could use a zener with a voltage just slitely
higher than the open circuit off voltage output. Put that in
series with the LED, to block the small output, and reduce
the series resistor to bring the brightness up.
Not sure what you're suggesting . . . can
you offer a schematic along with some
description of where the voltage drops are
expected and of what magnitude?
I am not familiar with the device outputing the
signal to the LED. Perhaps I am all wet in
assuming these outputs, See attached.
Roger
Message 8
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Subject: | Re: LED Ghosting |
At 08:52 AM 6/18/2014, you wrote:
I don't remember specifically which of your instruments has the
ghosting problem. I'll tell you my story, which may or may not be
relevant, but it may help others with a similar situation as mine.
When I first powered up my instrument panel, the red warning light
for my Grand Rapids EIS engine monitor glowed very dimly when the
panel was powered up but the engine monitor was turned off. Ghosting
went away when I turned the engine monitor on. Like you, I had
replaced an incandescent light with an LED. On the bench, the
ghosting seemed like a problem.
It was a legacy practice in aviation annunciator
lamp outputs to offer some way that an annunciator
can tell the pilot that the system driving that
annunciator is OFF. Using the normally closed
contacts of a relay ALWAYS works but if they
can be replaced at less cost, the solid state option is
preferred.
The output circuit depicted in the adaptation of
LED's to the B&C LR series regulators
http://tinyurl.com/cgnwr5k
is an exemplar approach to the task for incandescent
annunciators common to the time. The resistor between
the collector and base of the lamp driver causes
a 'powered down' LR3 to drive an annunciator lamp
into partial conduction . . .
In later years we added a remote sense lead to the
ov/lv detection system which causes the lv warn
to come alive when the bus becomes hot but before
the engine is started and irrespective of the
position of the alternator field switch. This
change of architecture eliminated the value of
'powered down' conduction of the annunciator
sorta went away.
The 'problem' can be eliminated by snipping out
the one-time-useful resistor. I think I'll
suggest that B&C eliminate that resistor in
future production and modify any regulators
that come back for other reasons.
However, I focused on other, bigger, problems and never got around to
fixing the ghosting problem. By the time I completed my flight test
phase, I understood that the ghosting was not a problem at all and
maybe even a benefit.
It CAN be eliminated . . . with a massaging of
performance facts . . .
I turn the engine monitor on before engine start and leave it on
until after engine shutdown. Since ghosting only occurs when the
master switch is on and the engine monitor is off, I never see
ghosting because the engine monitor is normally on whenever the
master switch is on. I now consider ghosting, if I ever see it, to
be a warning that I've forgotten to turn the engine monitor
on. "It's not a bug, it's a feature."
. . . it may have been just that under
alternative design goals. Without benefit of
documentation or conversation with the original
designer . . . its a WAG.
Bob . . .
Message 9
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Subject: | Re: LED Ghosting |
>
>
>I suggest we pay homage to our teachers one of whom once replied:
>"Dammit Bob, I'm a doctor, not a engineer" -Dr. Leonard McCoy-
>
>Unfortunately, this is a bit beyond my skillset. While the squiggly
>lines are not quite hieroglyphics to me, I'm not exactly sure what
>to do with them.
>
Not sure how to answer this . . . analysis and
resolution of some problems simply does not
move forward without good data.
Putting a resistor across the lamp/resistor
string SHOULD have fixed your problem. But the
narrative of your observed behavior left
me scratching my head . . . too much is
not yet known . . .
Emacs!
Bob . . .
Message 10
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Subject: | Re: LED Ghosting |
[quote="nuckolls.bob(at)aeroelect"]
>
> Not sure how to answer this . . . analysis and
> resolution of some problems simply does not
> move forward without good data.
>
> Putting a resistor across the lamp/resistor
> string SHOULD have fixed your problem. But the
> narrative of your observed behavior left
> me scratching my head . . . too much is
> not yet known . . .
>
> Bob . . .
Technically the resistor did fix the problem (ghosting). But it created a new
problem (dim LED). So now I'm working on the second problem while not re-introducing
the first problem.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425094#425094
Message 11
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Subject: | Re: LED Ghosting |
eschlanser wrote:
>
> donjohnston wrote:
> >
> >
> > "The engine analyzer people said it was designed for incandescent... "
>
>
> Here's a simple solution. Use an incandescent bulb such as this: http://tinyurl.com/kw8usxc
You are right, it is a solution. Just not very simple. Since I would have to scrap
the circuit board that the LEDs are mounted to and design a new one. And
since this is a incandescent bulb, it would have to be socketed. Which means redesigning
the warning panel assembly to be deep enough to accept the new light
bulb. Not sure how I would handle replacing the bulb when it burns out though.
Or I could just scrap the whole warning panel altogether. Then I'd have to fill
in that rectangular hole in the panel, drill holes for the 8 warning lights.
Come up with the circuit design for the new warning lights. etc., etc., etc.,
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425095#425095
Message 12
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Subject: | Re: Off Delay Cabin Light |
> I prefer simpler designs and hope to publish one here soon, using no ICs and
only six basic parts. It will do a "slow-fade dim-out".
As promised, here is a basic Sexy Slow-Fadeout Cabin Light that is very rugged
and very simple. I uses only six basic parts.
The main high-current switch is a LM395 Indestructible Power Transistor, but any
number of other NPN power transistors would do just fine. The timer stays on
for about R x C seconds, which here is 32 seconds. You can change this as you
like preferably with a higher-value resistor (because it's easier).
The transistor needs some heatsinking if you want it to dim a very big bunch of
LEDs. But some experimenting will determine what you need.
Two notes:
1) The previous "De-Slumpifier" also works well for this task, and you don't need
any "keep-alive" bus.
2) Cree sells 200/lumen per watt white leds now, so don't be stuck with the antiques
ones if you can use these.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425098#425098
Attachments:
http://forums.matronics.com//files/lamp_fade_out_timer_441.pdf
Message 13
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Subject: | Re: Off Delay Cabin Light |
Eric,
my computer says Page not found when I try to open the attachment.
Roger
Message 14
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Subject: | Re: LED Ghosting |
>
>
>Technically the resistor did fix the problem (ghosting). But it
>created a new problem (dim LED). So now I'm working on the second
>problem while not re-introducing the first problem.
That's the fact that does not make sense. The barefoot
string of two LEDS and a resistor function with a
current level on the order of 15 to 20 milliamps.
(First sketch in the document I published). This
is much lower than the typical incandescent lamp
at 80+ milliamps. Adding the resistor (second sketch)
adds another 12 to 14 milliamps for a total of
27 to 34 milliamps . . . much LOWER than the incandescent
lamp being replaced.
We can continue to flog this topic with all
manner of cut, paste, try, suppose, wish and
propose . . . with poor prospects for fixing
it and poorer prospects for understanding
root cause for the symptoms you've observed.
The second sketch 'fix' should have NO effect
on lamp intensity . . . the fact that it does
have an effect says we don't know squat about
what we're doing . . . yet.
Hence, the 'dim LED' is a mystery that
cannot be resolved without knowing the reason
for what appears to be a reduction of available
voltage. The experiments I asked you to conduct
went toward resolving the mystery.
Bob . . .
Message 15
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Subject: | Re: Off Delay Cabin Light |
Thanks Eric, the download worked for me.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425106#425106
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