Today's Message Index:
----------------------
1. 05:42 AM - Re: Ideas on painting panel? (Paul McAllister)
2. 05:51 AM - Re: Ideas on painting panel? (John Schroeder)
3. 06:22 AM - Re: amploc sensor (sarg314)
4. 09:47 AM - Re: Re: Load Dump mitigation (Jerzy Krasinski)
5. 09:49 AM - LM317 LED power supply (Glaeser, Dennis A)
6. 09:58 AM - Annunciators (Wayne Berg)
7. 10:00 AM - Re: Ideas on painting panel? (Jerzy Krasinski)
8. 10:55 AM - Re: Re: Load Dump mitigation (Paul Messinger)
9. 11:09 AM - Re: LM317 LED power supply (Alan Erickson)
10. 11:13 AM - Re: Re: KN65A DME (Dwight Frye)
11. 11:22 AM - Re: LM317 LED power supply (Richard Tasker)
12. 12:08 PM - List: wire selection (Glen Matejcek)
13. 12:32 PM - Re: LM317 LED power supply (Eric M. Jones)
14. 01:52 PM - Re: Re: overvoltage protection clamav-milter (Ken)
15. 03:58 PM - Re: List: wire selection (Paul Messinger)
16. 04:20 PM - Re: Re: KN65A DME (BobsV35B@aol.com)
17. 04:40 PM - Re: Re: Load Dump mitigation (Robert L. Nuckolls, III)
18. 05:22 PM - Re: wire selection (Tim Olson)
19. 07:48 PM - Re: LM317 LED power supply (glaesers)
20. 08:11 PM - Re: Potter&Brumfield (Dj Merrill)
21. 08:57 PM - Re: Re: Load Dump mitigation (George Braly)
22. 09:06 PM - Re: Re: Load Dump mitigation (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Ideas on painting panel? |
--> AeroElectric-List message posted by: "Paul McAllister" <paul.mcallister@qia.net>
Ron,
I painted mine with epoxy paint with a clear coat over the top. It seems to
be holding up okay. I used gray with a satin finish.
Paul
Message 2
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| Subject: | Re: Ideas on painting panel? |
--> AeroElectric-List message posted by: "John Schroeder" <jschroeder@perigee.net>
Ron -
Definitely flat paint. Gloss aids glare and reflections. Bad for night
flying. Top should also be very dark and flat, or covered with a dark,
flat, non-reflective fabric/leather/...
Cheers,
John
> What suggestions on painting? Should the bottom of brow be very dark? I
> imagine the top of the fiberglass does not want to be too dark so it does
> not heat up too much?
>
> I imagine I want flat on instrument module and brow, what is preference
> out
> there for face of panel, light / dark flat or gloss?
Message 3
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| Subject: | Re: amploc sensor |
--> AeroElectric-List message posted by: sarg314 <sarg314@comcast.net>
Perhaps I should have mentioned I was looking at the CS50 closed loop
current sensor. Not the PRO or AMP series.
--
Tom Sargent
Message 4
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: Jerzy Krasinski <krasinski@provalue.net>
Bob,
I wonder why did you select 5KP18 which begins to sink current (5mA) at
a voltage of approximately 21V? Is such a big voltage margin necessary?
5KP14 opens at a voltage of approximately 16V which seems to be
sufficiently higher than the battery voltage, and hopefully it would
clamp the output to a lower peak voltage.
Did you manage to find voltage versus current curves for these diodes?
How much voltage do we get accross the diode at the rated peak surge
current of 400A?
Jerzy
Message 5
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| Subject: | LM317 LED power supply |
--> AeroElectric-List message posted by: "Glaeser, Dennis A" <dennis.glaeser@eds.com>
I've been playing around with LEDs and decided to make a constant voltage
power supply using a LM317 voltage regulator. I bought one at Radio Shack
along with some resistors and wired it up to get a 3.5V output required for
the LEDs. Works great. But when I put 5 LEDs in parallel on it, the LM317
got pretty hot (no temp data, but way to hot to touch). The tech data said
it may need a heat sink, so this wasn't a total surprise, but I didn't
expect only 5 LEDs to cause it to heat up so much.
From their spec sheet (http://www.superbrightleds.com/specs/w5_specs.htm
<http://www.superbrightleds.com/specs/w5_specs.htm> ): the LEDs draw .03a at
3.5V which is .105W. The spec sheet also says the power dissipation for the
LEDs is .08W - I don't understand what that is vs. the calculated value.
Using the calculated value, all 5 LEDs draw .525W. The package says max
power for the LM317 is 15W, so that is why I am surprised it got so hot.
Dropping down to 3 LEDs, it still gets pretty warm - but touchable.
So my questions are:
Do these devices typically get that hot even when (what appears to be)
lightly loaded?
Are my calculations wrong somewhere?
What is the Power Dissipation value from the spec sheet vs. the calculated
power?
Is the Radio Shack device just a low quality unit - would I get different
results from something bought from DigiKey?
My application is for indicator lights, where potentially multiple LEDs can
share the same power source, if activated by grounding. Typically the only
time multiple lights would be on is prior to startup (i.e. LV, Fuel
pressure) - or if I get in real trouble on some dark and stormy night. Some
lights will be activated by applying power (i.e. Pitot Heat, not sure about
- ECM, EIS, OV) so no sharing there.
Is there any real advantage to using an LM317 circuit instead of just
resistors to drop the voltage to LEDs? The one I know is: the voltage to
the LED is constant despite fluctuating input voltage (no dimming when you
turn on a big load like the landing light or pitot heat). I was thinking
the LM317 was more efficient than just heating up a resistor, but now I'm
not so sure.
Thanks,
Dennis Glaeser
Message 6
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Seal-Send-Time: Tue, 4 Jan 2005 09:57:20 -0800
--> AeroElectric-List message posted by: "Wayne Berg" <wfberg@msn.com>
I am building a Van's RV-8 and have designed my own annunciator panel. I am using
LED light bars. I have dual Lightspeed ignitions that I would like to wire
up to the panel to indicate a failure of the ignition. They are interconnected
to automatically compensate for a failure of either and it is not noticeable
in engine sound or performance when one fails or is turned off. The only available
output from the Lightspeed is the tach output which is around 100mv per 100
rpm.
I would appreciate any suggestions you might have as to adapting the tach signal
to light the LED on the panel. The factory said that the tach output dropping
to zero would indicate system failure or shutdown.
Thanks for any help.
Wayne Berg
Message 7
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| Subject: | Re: Ideas on painting panel? |
--> AeroElectric-List message posted by: Jerzy Krasinski <krasinski@provalue.net>
Paul McAllister wrote:
>--> AeroElectric-List message posted by: "Paul McAllister" <paul.mcallister@qia.net>
>
>Ron,
>
>I painted mine with epoxy paint with a clear coat over the top. It seems to
>be holding up okay. I used gray with a satin finish.
>
>Paul
>
>
>
I made my panel top of carbon fiber and I left it with no painting,
happy with the good looking black color.
Recently, I discovered problems with operation of ELT. Checking the
panel mounted remote RLT indicator I found that the box made of cheap
plastic was badly deformed, sagging down, clearly showing that it was
overheated by the Oklahoma summer sun.
I will have to paint the cover with some white-ish color.
Stay away from dark panels.
Jerzy
Message 8
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
You are being somewhat unfair to Bob as I was the one that did the testing
and parts selection. Bob simply posted one reasonable part choice.
For more info please refer to my post yesterday.
As for your specific questions.
The purpose of the alternator load dump clamp is to protect the alternator
internal regulator NOT your aircraft electrical system. Thus the selection
of clamp voltage (in the internal regulator) is often as high as 30+ v.
There is an APPARENT issue with the rebuilt alternators Vans sells. I say
apparent as its not clear to many of us exactly what is causing the
alternator regulator to fail when the alternator is switched off line.
Remember auto alternators are designed for a system where its not possible
to remove the battery load when the engine is running except by wire
breakage or an uninformed mechanic. I have never heard of any internal
regulator that did not have load dump protection built in.
Most OVP protection circuits are set to trigger at around 16V. The minimum
clamp transorb V rating I could see being used, considering tolerance
buildup etc, was an 1.5K 18V unit. Also there is the matter of having a part
that is easy to find in reasonable quantity. Even at the 100 part level
there is only a few voltages stocked in the 5k size.
Most of the time to get specific parameters one must use the tabular data
and crunch the numbers.
I found that a 1.5k 18V transorb had a lower breakdown voltage than a 5K 18V
device. Not sure if that is due to different mfgrs or??
The part Bob specified or the part specified in my prior post are both well
suited to the defined task of alternator internal regulator protection and
both have been extensively tested in a real circuit.
Your questions seem to make me think you are also interested in keeping the
electrical system buss voltage as a reasonable level. This is a very
different case unless you are considering a no battery condition with the
alternator providing the power and perhaps a large cap as a load stabilizer.
This case is beyond the scope of the present issue.
Also I will be posting more in the days to come as I am still very much
under the weather and this is 50% of my total useful work per day right now.
Paul
----- Original Message -----
From: "Jerzy Krasinski" <krasinski@provalue.net>
Subject: Re: AeroElectric-List: Re: Load Dump mitigation
> --> AeroElectric-List message posted by: Jerzy Krasinski
<krasinski@provalue.net>
>
> Bob,
>
> I wonder why did you select 5KP18 which begins to sink current (5mA) at
> a voltage of approximately 21V? Is such a big voltage margin necessary?
>
> 5KP14 opens at a voltage of approximately 16V which seems to be
> sufficiently higher than the battery voltage, and hopefully it would
> clamp the output to a lower peak voltage.
>
> Did you manage to find voltage versus current curves for these diodes?
> How much voltage do we get accross the diode at the rated peak surge
> current of 400A?
>
> Jerzy
>
>
Message 9
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| Subject: | LM317 LED power supply |
--> AeroElectric-List message posted by: "Alan Erickson" <alaner_rv8@hotmail.com>
Howdy, Dennis! I'm assuming that you've hooked up the LEDs through
resistors, and I'll further assume that you've calculated it so that each
LED is taking 30ma as per the specs you gave. I also assume you're feeding
the 317 from a 12V rig.
Please, crosscheck all the math below before actually using it!! (better,
recalc from scratch)
The total current being drawn through the 317 is (5 * 0.030A) = 0.150A.
The voltage that the 317 is dropping is (14V - 3.5V) = 10.5V
P=IV, so the power being dissipated in the 317 is (0.150A * 10.5V) = 1.6W
Now, hit the LM317 specs:
http://www.national.com/ds/LM/LM117.pdf
You've probably got the TO-220 package which is listed on page 1 as the 'T'
package (the metal tab - careful to protect it, that tab is connected to
Vout, not ground! It also makes the whole chip wiggly on its pins). Go to
page 5, and look for the T package near the bottom, in the row marked
"thermal resistance, junction to ambient (no heat sink)". They're gonna tell
you here how fast the heat produced inside the chip gets transferred to an
air (or finger) temperature. For the T package, I read 50C/W. So in your
existing circuit you should expect a temperature rise of roughly
T = (1.6W)(50C/W) =80C
Now, going by Bob and Doug McKenzie's formula (double it and add 30), 80C is
about 190F. That's why it feels hot!
That was interesting and all, but the real question is what to do about it?
Well, if you don't want stuff getting that hot (I usually don't), you need
to change something in the equations above. There are a bunch of options,
but here's what I'd do:
Do you need to regulate the LED supply voltage? Probably not. Supply changes
of a few volts won't change the brightness much at all -- try calculating
the change in current through the LEDs for a change of 2V (remember the
resistors!), then look at your LED specs to see how much that changes the
light output -- and anyway what variation there is may be useful information
for the pilot. Your easiest option is to ditch the regulator, feed the LEDs
from the mains, and recalculate the resistors: R=V/I, where V is
(Vsupply-Vled). Vled is specified for the LED, and will be a coupla volts
(go to the LED specs) -- I'll assume Vled=2V:
R ~= (14V-2V)/0.030A = 400 ohms, close standard value = 390 ohms
Each resistor is now dissipating
P=IV=(0.030A)(14V-2V) = 0.36W, so use 0.5W resistors rather than 0.25W.
Another option: if you *do* want flicker-free LEDs, don't regulate down to
3.5V. It doesn't really matter what the voltage comes out as, as long as
it's regulated, right? Just recaclulate the LED resistors appropriately. If
you don't drop all those volts (14V-3.5V) in the regulator, then the power
dissipation *in the regulator* is much lower. Dissipate more power in each
LED's resistor to take the load off the regulator.
So: regulate to a voltage that is as high as possible, but which is
guaranteed to be lower than the electrical system. To throw a dart, try 10V
and recalculate the power dissipation and resistors:
Preg = IV = (14V-10V)(0.030A) = 0.120W , therefore
Treg = (0.120W)(50C/W) = 6C = 42F (no problems!)
Rled = V/I = (10V-2V)/0.030A = 270ohms
Presistor = (10V)(0.030A) = 0.3W (use 0.5W resistors)
Everything's fine now, and your LED supply is regulated if that's what you
want! Note that you don't even have to use an adjustable regulator if you
don't want the extra components: you could use an LM7808 for 8V output, for
example.
If you use a regulator, I would *highly* recommend using a 0.1uF ceramic
capacitor ('Shack is fine) on at least the output of the LM317 and LM78xx
series, or you risk bad behavior (oscillation). Also note their 'minimum
load current' on page 5, which means that you should connect an
appropriately-sized resistor from output to ground for when all the lights
are out - a frequent 'gotcha' on regulator circuit design!
Have fun!
Alan Erickson
Socorro, NM
8A, IO-360M1B6, 2xPlasma2+, invert, WW200RV
D-10a, 430, SL-30, ACS2002, AlTrak, Trio, ~Z-12
flight est. summer 05
|--> AeroElectric-List message posted by: "Glaeser, Dennis A"
|<dennis.glaeser@eds.com>
|
|I've been playing around with LEDs and decided to make a
|constant voltage power supply using a LM317 voltage regulator
..
|the LM317 got pretty hot
Message 10
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--> AeroElectric-List message posted by: Dwight Frye <dwight@openweave.org>
On Sun Jan 2 22:47:50 2005, BobsV35B@aol.com wrote :
>[ .. snip .. ]
>I do remember that route, but the current charts no longer show the
>appropriate beacons on either end nor do they show any airway other than the
ones
>based on the VORs.
>
>I have flown the New Orleans to Tampa route in my Bonanza many years ago,
>but I think it was after the GPS became available. I also flew it often in my
>previous life, but I usually had an INS available to back up the ADFs.
>
>I am still looking for a lower forty-eight LF route though!
Would the airway G13 over the outer banks of NC be what you are looking
for? I am not sure it is still commissioned (I thought they took down
some of the NDBs along that route a year or so ago) but a quick look
at my AOPA flight planner still shows it there.
The full airway is (or was, if it is gone now) from MQI->ZOLMN->HI->OUC so
runs from the NDB at Manteo to the NDB at Ocracoke Island. And even if the
airway is gone ... that is still a fun route to fly (as long as you keep a
sharp lookout for other sight-seers flying down the banks in the summer).
-- Dwight
do not archive
Message 11
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| Subject: | Re: LM317 LED power supply |
--> AeroElectric-List message posted by: Richard Tasker <retasker@optonline.net>
Possible reasons:
1. You didn't say what package the LM317 you are using is, but even with
the TO-3 (large metal case) the temperature rise will be about 32C per
watt of dissipation in the LM317. If we assume that you are starting
with 13.5V then the LM317 has 10V across it and is supplying 0.15A -
which gives 1.5W dissipation. That will give a 48C rise in case
temperature. If we assume a 25C ambient then the case is at 73C (163F)
which is too hot to touch. This is still well below the permissible
operating temperature. Any other package will be a worse case (hotter)
than the TO-3.
2. LEDs are current operated devices. That is, an LED should be driven
by a current source or a higher voltage source with a resistor in series
(simulating a current source). If you are providing a regulated 3.5V to
the LEDs the current drawn by any one LED could be (probably is) totally
different from what you are concluding from the data sheets. Have you
actually measured the current through your circuit? Obviously, if the
current is higher than you have stated, the power dissipated in the
LM317 will be higher.
As for your other questions: If you want the light output to be
constant with varying input voltages (when turning on heavy loads or if
the alternator fails and the voltage drops) you could use the LM317 to
regulate to a higher voltage (say 8 volts) and then use a resistor in
series with each LED (value chosen for desired brightness).
On the other hand, if you don't mind slight changes in brightness with
varying loads on your electrical system, there is no advantage in using
the LM317 over just using resistors.
The DigiKey part will work just the same as the RadShack part.
Dick Tasker
Glaeser, Dennis A wrote:
>--> AeroElectric-List message posted by: "Glaeser, Dennis A" <dennis.glaeser@eds.com>
>
>I've been playing around with LEDs and decided to make a constant voltage
>power supply using a LM317 voltage regulator. I bought one at Radio Shack
>along with some resistors and wired it up to get a 3.5V output required for
>the LEDs. Works great. But when I put 5 LEDs in parallel on it, the LM317
>got pretty hot (no temp data, but way to hot to touch). The tech data said
>it may need a heat sink, so this wasn't a total surprise, but I didn't
>expect only 5 LEDs to cause it to heat up so much.
>
>>From their spec sheet (http://www.superbrightleds.com/specs/w5_specs.htm
><http://www.superbrightleds.com/specs/w5_specs.htm> ): the LEDs draw .03a at
>3.5V which is .105W. The spec sheet also says the power dissipation for the
>LEDs is .08W - I don't understand what that is vs. the calculated value.
>
>Using the calculated value, all 5 LEDs draw .525W. The package says max
>power for the LM317 is 15W, so that is why I am surprised it got so hot.
>Dropping down to 3 LEDs, it still gets pretty warm - but touchable.
>
>So my questions are:
>Do these devices typically get that hot even when (what appears to be)
>lightly loaded?
>Are my calculations wrong somewhere?
>What is the Power Dissipation value from the spec sheet vs. the calculated
>power?
>Is the Radio Shack device just a low quality unit - would I get different
>results from something bought from DigiKey?
>
>My application is for indicator lights, where potentially multiple LEDs can
>share the same power source, if activated by grounding. Typically the only
>time multiple lights would be on is prior to startup (i.e. LV, Fuel
>pressure) - or if I get in real trouble on some dark and stormy night. Some
>lights will be activated by applying power (i.e. Pitot Heat, not sure about
>- ECM, EIS, OV) so no sharing there.
>
>Is there any real advantage to using an LM317 circuit instead of just
>resistors to drop the voltage to LEDs? The one I know is: the voltage to
>the LED is constant despite fluctuating input voltage (no dimming when you
>turn on a big load like the landing light or pitot heat). I was thinking
>the LM317 was more efficient than just heating up a resistor, but now I'm
>not so sure.
>
>Thanks,
>
>Dennis Glaeser
>
>
>
>
Message 12
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| Subject: | List: wire selection |
--> AeroElectric-List message posted by: "Glen Matejcek" <aerobubba@earthlink.net>
Hi Larry-
...The wire shown at http://www.skycraftsurplus.com/ is not aviation grade
wire it appears to me....
Indiana Larry, RV7 TipUp "SunSeeker"
I'm curious as to why you say that. Some of the wire / cable I've
purchased there has an MS number printed on it, some doesn't. It's all
fine stranded, tinned wire in Teflon or tefzel insulation. My
multi-conductor shielded cable does not have the MS number on the outside,
but it does have the numbered paper strip through the center with the
conductors. While not all of it is labelled "Mil Spec", I do believe it is
aircraft quality.
Regards,
gm
Message 13
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| Subject: | Re: LM317 LED power supply |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: "Glaeser, Dennis A"
<dennis.glaeser@eds.com>
>The spec sheet also says the power dissipation for the LEDs is .08W - I
don't understand what that is vs. the calculated value.
You are looking at the wrong end of the horse. Ignore it for your
application.
>Using the calculated value, all 5 LEDs draw .525W. The package says max
>power for the LM317 is 15W, so that is why I am surprised it got so hot.
>Dropping down to 3 LEDs, it still gets pretty warm - but touchable.
See below.
>Do these devices typically get that hot even when (what appears to be)
lightly loaded?
>Are my calculations wrong somewhere?
>What is the Power Dissipation value from the spec sheet vs. the calculated
>power?
See below
>Is the Radio Shack device just a low quality unit - would I get different
results from something bought from DigiKey?
When I go to Radio Shack, I always buy a pizza next door so as not to waste
the trip. But here the part is okay.
>Is there any real advantage to using an LM317....
Any application where you don't want to adjust the brightness individually
needs only a resistor.
Dennis,
It would be nice to not have the penalty of a hot part when reducing the
voltage, but linear regulators like the LM317 just dissipate power in
exactly the same way as a series resistor. But the advantages the LM317
yields are many, dimmability, ouput regulation, noise filtering (often
overlooked!), built-in over-current protection, etc.
Looking at the voltage drops gives us a clue to what happens. The voltage
drop from the power input of the 317 to its output must yield a voltage that
demanded by the input of the LEDs (or series chain of LEDs). For example
the 317 input is 14Vbatt and the output is 2V. Then we must have a voltage
drop of 12V. The power dissipation of the LM317 is the voltage drop X the
current (ignoring a small amount for the adjustment current), so the power
dissipation would be W=12V X 0.030=0.36 Watts.
If you add LEDs in parallel you dissipate 0.36W for each one. For 5 LEDs you
dissipate over 1.8 W. For the TO-220 Package this leads to a package
temperature of 20 degC+1.8 X 50 degC/W or 110 degC (as you say...way too hot
to touch).
So what's going on here? Well, you could run the LEDs in series, then the
current would still be 0.030A but the voltage needed would be 5 X 2V or 10
volts, and the voltage drop would be only 14V-10V=4V. Thus the power
dissipation would be 4V X 0.030=0.12W. and the temperature would be 20
degC+0.12 X 50 degC/W or 32 degC (or just slightly warm to the touch).
Suggestions: String up as many LEDs in series as you can get away with, then
add parallel strings AND a heatsink. Always use a resistor in parallel
strings to help prevent cascade failures and in series strings to limit the
current. (I know some LED guys don't use them....but HAH!)
Other suggestion: Buy mine. Four for $99 dollars. Guaranteed 1 ampere
output.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
"I tried being reasonable--I didn't like it!"
--Clint Eastwood
Message 14
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|
| Subject: | Re: overvoltage protection clamav-milter |
version 0.80j on juliet.albedo.net
clamav-milter version 0.80j
on juliet.albedo.net
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
Nope they are apparently backordered there but I'll keep an eye on mouser.
Ken
Robert McCallum wrote:
>--> AeroElectric-List message posted by: Robert McCallum <robert.mccallum2@sympatico.ca>
>
>They appear to be available from mouser in quantities of 1 for $1.34 each
>http://www.mouser.com/index.cfm?&handler=data.listcategory&D=576-5KP18&terms=576-5KP18&Ntt=*5765KP18*&N=0&crc=true
>Bob McC
>
>Ken wrote:
>
>
>
>>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>>
>>Neat!
>>Anybody find a source for small quantities of the 5KP18 yet?
>>Ken
>>
>>
>>
Message 15
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| Subject: | Re: List: wire selection |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
Tefzel is fine and Teflon is NOT suitable for any aircraft etc. Cold flow.
Been discussed here last summer. Some businesses seem to ignore how
important insulation is and promote Teflon insulation.
Beware it can short out after months or years depending on the stress on the
wire in the bundle etc Really bad when using connectors with wire grips.
MS numbers in and of themselves do not mean its aircraft wire. Hundreds of
MS numbered wire types with most not suitable for aircraft.
Teflon insulated wire has been banned from aircraft and aerospace in general
for over 25 years.
Paul
----- Original Message -----
From: "Glen Matejcek" <aerobubba@earthlink.net>
Subject: AeroElectric-List: List: wire selection
> --> AeroElectric-List message posted by: "Glen Matejcek"
<aerobubba@earthlink.net>
>
> Hi Larry-
>
> ...The wire shown at http://www.skycraftsurplus.com/ is not aviation grade
> wire it appears to me....
>
> Indiana Larry, RV7 TipUp "SunSeeker"
>
> I'm curious as to why you say that. Some of the wire / cable I've
> purchased there has an MS number printed on it, some doesn't. It's all
> fine stranded, tinned wire in Teflon or tefzel insulation. My
> multi-conductor shielded cable does not have the MS number on the outside,
> but it does have the numbered paper strip through the center with the
> conductors. While not all of it is labelled "Mil Spec", I do believe it
is
> aircraft quality.
>
> Regards,
>
> gm
>
>
Message 16
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--> AeroElectric-List message posted by: BobsV35B@aol.com
In a message dated 1/4/2005 1:14:06 P.M. Central Standard Time,
dwight@openweave.org writes:
Would the airway G13 over the outer banks of NC be what you are looking
for? I am not sure it is still commissioned (I thought they took down
some of the NDBs along that route a year or so ago) but a quick look
at my AOPA flight planner still shows it there.
Good Evening Dwight,
A quick look at my Jeppesen charts does not reveal that airway to me, but it
could be I don't know where to look!
I agree that route is fun to fly. I like to go a half mile off shore at
about two hundred feet MSL
Last time I was down there was for the Wright Flyer extravaganza in 2003.
That was a ball, flight or no flight.
Happy Skies,
Old Bob
AKA
Bob Siegfried
Ancient Aviator
Stearman N3977A
Brookeridge Airpark LL22
Downers Grove, IL 60516
630 985-8502
Message 17
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 11:44 AM 1/4/2005 -0600, you wrote:
>--> AeroElectric-List message posted by: Jerzy Krasinski
><krasinski@provalue.net>
>
>Bob,
>
>I wonder why did you select 5KP18 which begins to sink current (5mA) at
>a voltage of approximately 21V? Is such a big voltage margin necessary?
>
>5KP14 opens at a voltage of approximately 16V which seems to be
>sufficiently higher than the battery voltage, and hopefully it would
>clamp the output to a lower peak voltage.
Why would one wish to select a lower voltage?
>Did you manage to find voltage versus current curves for these diodes?
>How much voltage do we get accross the diode at the rated peak surge
>current of 400A?
Only the point data charts that are offered by the manufacturers.
You're never going to see 400A . . . the MOST you can ever
see is the alternator's maximum capability.
During a REAL ov condition, you want enough headroom between
onset of load-dump mitigation and the reaction time of an
OV protection system so that you don't pop the Transorb. I
selected the 5KP18 as likely to stay out of the OV protection
loop while meeting the need to limit load-dump transients
to levels well inside DO-160 recommendations.
Keep in mind also that we're probably only concerned with
alternators having after-market regulators in them. I cannot
imagine that a modern alternator manufacturer will not account
for the load dump transient in design and selection of components
in their regulators. It would be interesting to see the pedigree
on regulators that failed when the alternator was unloaded in
a Figure Z-24 configuration.
The important data point from Paul's experiments is that
load dump energies are quite low. I suspected this given the
relative sizes of components offered specifically for the
purpose of standing off alternator load-dump events. I'm negotiating
for a used alternator test stand and should be able to refine
the data base next spring (my garage shop isn't heated). In
the mean time, I'm reasonably certain that adding the 5KP18
will mitigate the problems cited by Van's builders.
Others may have different criteria for selecting lower targets
for peak voltage but I'm comfortable with DO-160 recommendations.
I've not found it difficult to work within those bounds for 35
years or so. A part recommended for 14V load dump mitigation
was discussed on this list some months ago. It's the ST-MicroElectronics
LDP24A which has a threshold voltage of 24 volts and clamps
a 30A dump at about 40 volts. The 5KP18 will clamp a 100A
dump to some value less than 30 volts . . . quite comfortably
inside the limits of DO-160 and plenty of headroom for
OV protection to do its job independently from the
load-dump protection.
Bob . . .
Message 18
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| Subject: | Re: wire selection |
--> AeroElectric-List message posted by: Tim Olson <Tim@MyRV10.com>
Sorry to have to keep this thread going, but I have a note to add...
John, you said the same amount of 22759/16 wire from wiremasters.net
was $.05/ft.
I just went online and pulled up their 22 ga. wires....all 22ga
basically (except white) was listed as: $79.000/MFT, which if I'm
thinking right is $.079/ft. White was $.066/ft.
Where did you see the $.05/ft?? Is the pricing better than that
if you call them via phone?
Tim
John Schroeder wrote:
> --> AeroElectric-List message posted by: "John Schroeder" <jschroeder@perigee.net>
>
> On Mon, 3 Jan 2005 21:17:08 -0600, LarryRobertHelming
> <lhelming@sigecom.net> wrote:
>
>
>>Try Steinair.com (www.steinair.com) for aviation wire priced at or near
>>lowest prices. You will need awg22 wire. Try to get a hundred ft. each
>>of red, black, blue, green, yellow, and what ever other color he carries
>>awg22 in. That will be your most needed wire size. You will need some
>>heavier
>>wires also, but you are on your own in making those estimations. BandC
>>is a good source for quality stuff also.
>
>
> Larry-
>
> If you buy 100 ft. of each of the 7 colors of 22 AWG listed on Steinair,
> it is 700' x $0.13 or $91.
> The same amount of wire (22759/16) in the same gage and same colors is 700
> x $.05 or $35 at Wiremasters.com. Even with their $50 minimum, you save
> $41. I certainly would put together an order of the 22 AWG (I totally
> agree that color coding is the way to go), 150' of 20 AWG (Red & Black)
> and at least 150 ft of red and black 18 AWG. Call Deb Sullivan at
> Wiremasters and have her price it.
>
> The value of Steinair is considerable because you can get short lengths of
> most any wire and a wide range of other electrical-related goodies.
> However, I believe that the figures above make a tight case for buying the
> initial load of wire at Wiremasters.
>
> Cheers,
>
> John
>
> PS: I have no financial interest in Wiremasters. I just have a warm
> feeling of great service at very good prices.
>
Message 19
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| Subject: | Re: LM317 LED power supply |
--> AeroElectric-List message posted by: "glaesers" <glaesers@wideopenwest.com>
Alan, Dick, and Eric,
Thanks for the explanations! I guess the first thing I need to do is read
the whole spec document (not just stop at the formula for Vout ...). But
then I had the power dissipation wrong, so I would have still had the
question. Eric nailed my problem - looking at the wrong end.
Just to fill in the blanks: Alan gets points for correct assumptions (except
for the resistors). I did get the TO-220 package. I'm currently just using
a couple of 6V lantern batteries in series for my sandbox. That also allowed
me to switch between 6V and 12V and see that the output stayed at 3.5V. I
just connected the LEDs in parallel across Vout - no series resistors -
that's what I was looking to eliminate (before you guys pointed out the
error of my ways). I had this misguided notion that resistors aren't
'elegant'.
I just measured the current for 3 LEDs - started out at over 180ma and
climbed to the 190s in a few seconds - my simple multi-meter is only good
for 200ma (has a .315a fuse) so I disconnected and don't know where it would
have stopped, so score one for Dick. I guess no resistors means not much
current limiting going on!
Sounds like just plain old resistors are the best way to go (simple is
elegent too). The lights in question are fault lights, so they aren't on
much, and when they are, I don't think flickering will be my immediate
concern...
I will be using LEDs to backlight my panel legends, and I don't want those
to flicker, so Eric's "EGPAVR" is on my parts list - as well as some
resistors.
Thanks again for limiting my trip into the weeds...
Dennis
Message 20
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| Subject: | Re: Potter&Brumfield |
--> AeroElectric-List message posted by: Dj Merrill <deej@thayer.dartmouth.edu>
Speedy11@aol.com wrote:
> --> AeroElectric-List message posted by: Speedy11@aol.com
>
> I got some P&B W31 series circuit breakers (they are the ones with switches)
> from Steinair and the toggle switch in the breaker is loose in all of them.
> It will surely vibrate in an aircraft. Does anyone know if it is normal for
> the toggle switch in this breaker to be loose? To clarify, imagine holding a
> normal bat switch in your fingers and it moves around in the housing.
> Stan Sutterfield
> Tampa
> www.rv-8a.net
Hi Stan,
I have about a dozen of these in my Glasair.
The switch handle does feel a bit loose in the housing,
but I have not had any trouble with them. The plane was built in
1984 and there is a good chance that most of them
are the original installation.
-Dj
Message 21
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
Bob,
With the battery off line, I have repeatedly been able to destroy 5KP18 devices
with load dumps from 40 amp alternators on 14 volt systems.
In my experience, nothing short of a very active and robust OV clamp circuit,
with lots of capacitance also on line, is sufficient to prevent the destruction
of the 5KP18 devices - - - in which case those devices become unnecessary.
Regards, George
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III
Subject: Re: AeroElectric-List: Re: Load Dump mitigation
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 11:44 AM 1/4/2005 -0600, you wrote:
>--> AeroElectric-List message posted by: Jerzy Krasinski
><krasinski@provalue.net>
>
>Bob,
>
>I wonder why did you select 5KP18 which begins to sink current (5mA) at
>a voltage of approximately 21V? Is such a big voltage margin necessary?
>
>5KP14 opens at a voltage of approximately 16V which seems to be
>sufficiently higher than the battery voltage, and hopefully it would
>clamp the output to a lower peak voltage.
Why would one wish to select a lower voltage?
>Did you manage to find voltage versus current curves for these diodes?
>How much voltage do we get accross the diode at the rated peak surge
>current of 400A?
Only the point data charts that are offered by the manufacturers.
You're never going to see 400A . . . the MOST you can ever
see is the alternator's maximum capability.
During a REAL ov condition, you want enough headroom between
onset of load-dump mitigation and the reaction time of an
OV protection system so that you don't pop the Transorb. I
selected the 5KP18 as likely to stay out of the OV protection
loop while meeting the need to limit load-dump transients
to levels well inside DO-160 recommendations.
Keep in mind also that we're probably only concerned with
alternators having after-market regulators in them. I cannot
imagine that a modern alternator manufacturer will not account
for the load dump transient in design and selection of components
in their regulators. It would be interesting to see the pedigree
on regulators that failed when the alternator was unloaded in
a Figure Z-24 configuration.
The important data point from Paul's experiments is that
load dump energies are quite low. I suspected this given the
relative sizes of components offered specifically for the
purpose of standing off alternator load-dump events. I'm negotiating
for a used alternator test stand and should be able to refine
the data base next spring (my garage shop isn't heated). In
the mean time, I'm reasonably certain that adding the 5KP18
will mitigate the problems cited by Van's builders.
Others may have different criteria for selecting lower targets
for peak voltage but I'm comfortable with DO-160 recommendations.
I've not found it difficult to work within those bounds for 35
years or so. A part recommended for 14V load dump mitigation
was discussed on this list some months ago. It's the ST-MicroElectronics
LDP24A which has a threshold voltage of 24 volts and clamps
a 30A dump at about 40 volts. The 5KP18 will clamp a 100A
dump to some value less than 30 volts . . . quite comfortably
inside the limits of DO-160 and plenty of headroom for
OV protection to do its job independently from the
load-dump protection.
Bob . . .
---
---
Message 22
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 11:09 PM 1/3/2005 +0000, you wrote:
>--> AeroElectric-List message posted by: "Steve Sampson"
><steve@lbho.freeserve.co.uk>
>
>Bob - sorry if I am being obtuse. I have Z13A and the diagram is I think as
>before with one added component. I see the 5KP18 connected between the B -
>lead (power) and what?
Case of the alternator. Many alternators have ground studs.
If so, use that. Otherwise, a cooling shroud screw or
other hardware on alternator case might suffice. If this
is impractical, install Transorb on the starter contactor.
Run from fat-wire output terminal to mounting base (assuming
metal firewall).
>(I dont see note XX) There are only three wires (from
>memory) coming off the VANS unit and they are spoken for. Presumably its to
>ground? What is a 5KP18 and how does this function.
See:
http://www.littelfuse.com/data/en/Data_Sheets/5kp_revised.pdf
http://www.powerdesigners.com/InfoWeb/design_center/Appnotes_Archive/AN9312.pdf
Bob . . .
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