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tim2542(at)sbcglobal.net
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 Posted: Wed Mar 21, 2012 12:57 pm Post subject: Annunciator lights |
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Hey gang!
I built an annunciator panel using these LED's:
http://tinyurl.com/85r8duf
Now that Im flying I find they are failing almost weekly. I need to
replace them or fix the problem. They incorporate an integral resistor
and are rated at 12V. I'm looking for a more durable replacement, maybe
something that could be retrofitted into the existing lens as the led
and resistor will slide out the back side.
Any ideas welcome!
Thanks, Tim
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mrspudandcompany(at)veriz
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| Posted: Wed Mar 21, 2012 1:35 pm Post subject: Annunciator lights |
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I built an annunciator panel using these LED's:
http://tinyurl.com/85r8duf
Now that Im flying I find they are failing almost weekly. I need to
replace them or fix the problem.
You have LEDs rated for 3-12V and you are running them at
14+ volts. The current flow is too high with this higher voltage and this
is most likely why they are failing. If you really like these indicators,
you could put in series resistors, or put in lights with a higher voltage
rating.
Roger
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rparigoris
Joined: 24 Nov 2009
Posts: 792
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| Posted: Wed Mar 21, 2012 2:21 pm Post subject: Annunciator lights |
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I incorporated a number of Pep Boys LEDs in my panel. The reason I like them is they are slightly longer than a normal LED of that diameter. They are sold LEDs that can be used with 12 volts. The resistors they are using are too small, way too fragile, they didn't clean them before soldering, they did a very poor job soldering and the wire they use just doesn't solder that well. Net is I had several fail on the bench, some the solder joint failed, some the solder joint was high resistance and some the resistor broke. I still like the LEDs, so I just put my own resistor and wires on them and all is well. You can have a look at Hosfelt electronics for LEDs, or www.besthongkong.com if you want to buy a lot of stuff. You don't have to put the resistor inside your annunciator, it can go anywhere along the circuit. Doing the trick where you take a resistor with a leg to the left and a leg to the right, now you take a wire coming from the right, pass the resistor and solder to the left leg, then take a wire coming from the left, pass the resistor and connect it to the right and cover with a piece of heat shrink works very nice.
I don't have any pics with clear shrink tubing, but here's a diode in series:http://www.europaowners.org/main.php?g2_itemId=82005&g2_imageViewsIndex=1
Here's a resistor in series:
http://www.europaowners.org/main.php?g2_itemId=82008&g2_imageViewsIndex=1
Ron Parigoris [quote][b]
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nuckolls.bob(at)aeroelect
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| Posted: Wed Mar 21, 2012 4:48 pm Post subject: Annunciator lights |
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At 03:55 PM 3/21/2012, you wrote:
| Quote: | --> AeroElectric-List message posted by: Tim Andres <tim2542(at)sbcglobal.net>
Hey gang!
I built an annunciator panel using these LED's:
http://tinyurl.com/85r8duf
Now that Im flying I find they are failing almost weekly. I need to replace them or fix the problem. They incorporate an integral resistor and are rated at 12V. I'm looking for a more durable replacement, maybe something that could be retrofitted into the existing lens as the led and resistor will slide out the back side. |
What colors are you needing? Can you send me one
of these fixtures . . . or at least take some good
pix of the disassembled hardware as supplied.
LEDs are not generally very fragile. Are you sure it's
the LED that's failing and not the resistor? Some years
ago we had some discussion about LED fragility and life
vs. intensity here on the List. I took issue with a few
readers who cited 'not to exceed' ratings for LEDs lest
they depart for the happy glowing ground.
I took a 10mm LED rated at 30 mA and wired it to a wall-wart
biased up at about 4x that rating. I plugged it into an
outlet in my garage and left it. You could see rather
well in a darkened garage from the emitted light.
Over a year later, I took it off the wall still illuminated.
I didn't measure it's light output to see if it degraded
but it certainly didn't go into gross failure.
For use in annunciators where the lights are OFF most
of the time, it might be a good idea to over-drive the
LEDs in the interest of sun-light viewable performance.
There are some honk'n LEDs available. I bought some 10mm
reds and greens from this guy for a courtroom, table-top
demonstrator . . .
http://tinyurl.com/7jlgymk
Very adequate for getting one's attention in a well lit
courtroom. This seller
http://tinyurl.com/7n75xu2
has some killer whites rated at 1W. These might do
what you want depending on the ability of your caps
to set the color when illuminated with white led.
This much power in an LED probably calls for some
heat-sinking . . . but you may find that you can
run them a lot cooler and still get the necessary
light.
Bob . . . [quote][b]
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tim2542(at)sbcglobal.net
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| Posted: Wed Mar 21, 2012 5:14 pm Post subject: Annunciator lights |
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On 3/21/2012 5:46 PM, Robert L. Nuckolls, III wrote: | Quote: | At 03:55 PM 3/21/2012, you wrote:
| Quote: | --> AeroElectric-List message posted by: Tim Andres <tim2542(at)sbcglobal.net> (tim2542(at)sbcglobal.net)
Hey gang!
I built an annunciator panel using these LED's:
http://tinyurl.com/85r8duf
Now that Im flying I find they are failing almost weekly. I need to replace them or fix the problem. They incorporate an integral resistor and are rated at 12V. I'm looking for a more durable replacement, maybe something that could be retrofitted into the existing lens as the led and resistor will slide out the back side. |
What colors are you needing? Can you send me one
of these fixtures . . . or at least take some good
pix of the disassembled hardware as supplied. |
Thanks Bob! I'll have to check if its the resistors that failed next time I get to the hangar but I noticed some of the on-line LED/resistor calculators call for a 1/2 w resistor and the ones installed in the fixtures look like 1/8w. I'll report back but have already bought new LEDs to fix them with and in fact found some blinking ones to boot that I'll use on my OP light.
Thanks, Tim
[quote][b]
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nuckolls.bob(at)aeroelect
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| Posted: Thu Mar 22, 2012 8:42 am Post subject: Annunciator lights |
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| Quote: | | Thanks Bob! I'll have to check if its the resistors that failed next time I get to the hangar but I noticed some of the on-line LED/resistor calculators call for a 1/2 w resistor and the ones installed in the fixtures look like 1/8w. I'll report back but have already bought new LEDs to fix them with and in fact found some blinking ones to boot that I'll use on my OP light. |
One caveat on blinking LEDs . . . they're not
very bright. When you're designing annunciators
for airplanes, your dynamic range for ambient
lighting is huge . . . especially for a bubble
canopy airplane.
I've used blinking LEDs in SERIES with high
intensity devices with some success. But the
most elegant approach for attention getting is
to have a dedicated hardware flasher for the
LED. It can be pretty simple:
[img]cid:.0[/img]
This little flasher board made with surface
mount components can be as small as .4" on
a side, maybe even smaller.
If you find that you need to over-drive an
LED to meet your illumination design goals (e.g. say
50mA from a 14v source) the series resistor
would be something on the order of
10/.05 or 200 ohms. 10 Volts dropped
at 50 mA is 500 milliwatts . . . so
using a 1W resistor would not be a bad
idea for keeping surface temperatures
down.
If you've had failures of the COTS components
then it doesn't much matter whether it was
due to resistor or lamp failure . . . the
events demand evaluation and modification
of the design to achieve a useful level
of confidence.
Bob . . .
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Float Flyr
Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland
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| Posted: Thu Mar 22, 2012 11:14 am Post subject: Annunciator lights |
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Bob:The specs say 240Kmcd(at)300m​A . What exactly is a Kmcd? I have some ideas but none seems to fit unless this lamp will blister paint at ten feet.. Noel
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III
Sent: March 21, 2012 10:17 PM
To: aeroelectric-list(at)matronics.com
Subject: Re: Annunciator lights
At 03:55 PM 3/21/2012, you wrote:
--> AeroElectric-List message posted by: Tim Andres <tim2542(at)sbcglobal.net (tim2542(at)sbcglobal.net)>
Hey gang!
I built an annunciator panel using these LED's:
http://tinyurl.com/85r8duf
Now that Im flying I find they are failing almost weekly. I need to replace them or fix the problem. They incorporate an integral resistor and are rated at 12V. I'm looking for a more durable replacement, maybe something that could be retrofitted into the existing lens as the led and resistor will slide out the back side.
What colors are you needing? Can you send me one
of these fixtures . . . or at least take some good
pix of the disassembled hardware as supplied.
LEDs are not generally very fragile. Are you sure it's
the LED that's failing and not the resistor? Some years
ago we had some discussion about LED fragility and life
vs. intensity here on the List. I took issue with a few
readers who cited 'not to exceed' ratings for LEDs lest
they depart for the happy glowing ground.
I took a 10mm LED rated at 30 mA and wired it to a wall-wart
biased up at about 4x that rating. I plugged it into an
outlet in my garage and left it. You could see rather
well in a darkened garage from the emitted light.
Over a year later, I took it off the wall still illuminated.
I didn't measure it's light output to see if it degraded
but it certainly didn't go into gross failure.
For use in annunciators where the lights are OFF most
of the time, it might be a good idea to over-drive the
LEDs in the interest of sun-light viewable performance.
There are some honk'n LEDs available. I bought some 10mm
reds and greens from this guy for a courtroom, table-top
demonstrator . . .
http://tinyurl.com/7jlgymk
Very adequate for getting one's attention in a well lit
courtroom. This seller
http://tinyurl.com/7n75xu2
has some killer whites rated at 1W. These might do
what you want depending on the ability of your caps
to set the color when illuminated with white led.
This much power in an LED probably calls for some
heat-sinking . . . but you may find that you can
run them a lot cooler and still get the necessary
light.
Bob . . . | Quote: | | http://www.matronics.com/Navigator?AeroElectric-List |
01234567
[quote][b]
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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats |
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Thu Mar 22, 2012 1:44 pm Post subject: Annunciator lights |
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At 02:12 PM 3/22/2012, you wrote:
| Quote: | Bob:
The specs say 240Kmcd(at)300m​A . What exactly is a Kmcd? I have some ideas but none seems to fit unless this lamp will blister paint at ten feet..
|
It's a bit of silliness . . . an mCd is a milli-candella. Or
1/1000th of one candella
http://en.wikipedia.org/wiki/Candela
240,000 mCandelas reduces down
to 240 Candelas, the "K" and "m"
wipe each other out.
Bob . . . [quote][b]
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