Today's Message Index:
----------------------
1. 06:22 AM - Re: Modifying 12V LED Strip Lighting to work in 24/28V Aircraf (Eric M. Jones)
2. 06:29 AM - Re: Re: Unapproved ELT antenna? (Ken)
3. 08:37 AM - Using LEDs in Series (Eric M. Jones)
4. 09:35 AM - Re: Using LEDs in Series (Christopher Cee Stone)
5. 11:08 AM - Re: Using LEDs in Series (Eric M. Jones)
6. 11:46 AM - HUD for GA aircraft (Jerome Sipple)
7. 01:01 PM - Re: Re: Using LEDs in Series (Henador Titzoff)
8. 01:25 PM - book (Gordon Parker)
9. 01:43 PM - Re: Using LEDs in Series (Eric M. Jones)
10. 02:10 PM - Re: HUD for GA aircraft (Peter Pengilly)
11. 04:10 PM - Re: book (Robert L. Nuckolls, III)
12. 07:08 PM - Re: Latching Relay Redux (user9253)
13. 07:58 PM - Re: Re: Using LEDs in Series (Henador Titzoff)
Message 1
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| Subject: | Re: Modifying 12V LED Strip Lighting to work in 24/28V |
Aircraf
Wrong polarity...Rookie mistake see attached correction....
--------
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=379571#379571
Attachments:
http://forums.matronics.com//files/modify_led_strip_lighting_for_24_28_volts_reva_199.pdf
Message 2
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| Subject: | Re: Unapproved ELT antenna? |
Exactly but there still seems to be misunderstanding...
When I follow the manufacturer's instructions and do the 3 month self
test, I was surprised to learn that my ACK E-04 unit immediately
transmits a short live 406 test burst. I know this because I then get an
email from the Canadian Search and Rescue center confirming receipt of
my "test signal". Unlike other pilots I've spoken to, I will continue to
follow the manufacturer instructions. It would seem that RCC has no
problem recognizing these as "test bursts" and there is no need for any
coordination with any authority when doing the self test. They obviously
know whose ELT it is. The GPS position does not go out on the test burst
of this unit because the self test is supposed to be done WITHOUT
aircraft power or GPS info being fed to the unit.
On my unit the self test means pressing the black "test/reset" button
NOT the red Emergency button. But the labelling is applied by the
installer and can be reversed. In fact the rev 1.6 installation manual
actually has the photo on Page 1 reversed. However the text says
"Caution: The ON position marking on the placard must be aligned with
the red switch, the TEST/RESET marking must be over the black switch
(Fig. 5)". Perhaps some are installed backwards and that has caused
some problems leading to folks now avoiding the self tests??
BTW ACK no longer recommends using the Ameriking RCPI (panel indicator)
with the ACK E-04. There is a wiring reversal required if you do attempt
to do that but mine did not function even with the reversed wiring
connector.
Ken
On 25/07/2012 10:15 AM, Richard Girard wrote:
> Stu, The following are excerpts from AIM section 6-2-5, Emergency
> Locator Transmitter (ELT), dealing with testing, false alarms, and
> reporting.
> Testing
>
> 1. ELTs should be tested in accordance with the manufacturer's
> instructions. This should be done, preferably, in a shielded or screened
> room or specially designed test container to prevent the broadcast of
> signals, which could trigger a false alert.
>
> 2. When this cannot be done, aircraft operational testing is authorized
> as follows:
>
> (a) _Analog 121.5/243 MHz ELTs should only be tested during the first
> five minutes_ after any hour. If operational tests must be made outside
> of this period, they should be coordinated with the nearest FAA Control
> Tower or Flight Ser-vice Station. Tests should be no longer than three
> audible weeps. If the antenna is removable, a dummy load should be
> substituted during test procedures.
>
> (b) _Digital 406 MHz ELTs should only be tested in accordance with the
> unit's manufacturer's instructions._
>
> (c) Airborne tests are not authorized.
>
> Rick
>
>
> On Wed, Jul 25, 2012 at 4:39 AM, Stuart Hutchison
> <stuart@stuarthutchison.com.au <mailto:stuart@stuarthutchison.com.au>>
> wrote:
>
> __
> Hi Rick,
> I appreciate that 121.5 radiation is a measure of success, but not
> sure if you guys are talking about a 406 beacon.
> You're best not to transmit live without approval ... otherwise, in
> no time at all (one 406 data burst) you will have triggered a
> DISTRESS phase at the RCC.
>
> Kind regards, Stu______
>
>
> ------------------------------------------------------------------------
> *From:* owner-aeroelectric-list-server@matronics.com
> <mailto:owner-aeroelectric-list-server@matronics.com>
> [mailto:owner-aeroelectric-list-server@matronics.com
> <mailto:owner-aeroelectric-list-server@matronics.com>] *On Behalf Of
> *Richard Girard
> *Sent:* Wednesday, July 25, 2012 7:21 AM
> *To:* aeroelectric-list@matronics.com
> <mailto:aeroelectric-list@matronics.com>
> *Subject:* Re: AeroElectric-List: Re: Unapproved ELT antenna?
>
> David, The antenna has definitely been hacked off. I have an
> identical Ameri-King ELT on my personal airplane and it is about 7
> to 8 inches longer and has a ball end, no saw marks of ragged shrink
> tubing.
> I called the Wichita FSDO and got the answer. I can replace the
> antenna for the owner with an unaltered correct one, or I can get a
> ferry permit to fly it home to him and he can deal with it.
> On the sufficient signal strength, the rule is basically there to
> require a check to see that the antenna is indeed radiating, i.e.
> connected properly to the radio. Get your hand held, tune to 121.5,
> activate the ELT, see that you get a signal on the hand held, and
> your done.
> The inspector was kind enough to suggest a local shop that might
> have an antenna, Bevan Rabell, and the good folks there are trying
> to help.
>
> Thanks Guys,
> Rick Girard
> do not archive
>
> On Tue, Jul 24, 2012 at 11:33 AM, Kelly McMullen
> <kellym@aviating.com <mailto:kellym@aviating.com>> wrote:
>
> <kellym@aviating.com <mailto:kellym@aviating.com>>
>
> The requirements are in the TSO. The FARs require compliance
> with the TSO. TSO approval is on the transmitter with antenna,
> which prevents substitution with anything but identical antenna
> or one the manufacturer has determined to perform identically.
>
>
> On 7/24/2012 8:14 AM, D L Josephson wrote:
>
> Sorry, there should have been more detail. The point is that
> the FAR's don't specify how to measure radiated output.
> Maybe it's in the manufacturer's instructions, maybe not, in
> which case you're on your own... different shops use
> different methods like using a portable radio with no
> antenna or a remote receiver to see whether there is
> "sufficient signal radiated from its antenna."
> But check with Ameri-King, the shortened antenna may be
> factory length.
>
> David
>
>
Message 3
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| Subject: | Using LEDs in Series |
> This raises a good question: is it okay to light a strip of LEDs by just wiring
them in series in a quantity such that each LED sees the appropriate voltage
drop? This would seem to eliminate the (admittedly small) energy loss from heating
up resistors. On the other hand, failure of one LED would darken the whole
string. Thoughts?Dan
Great questionand one that needs a proper answer.
LEDs have a characteristic called Forward Voltage (or Vf). This means that the
LED will not light until the voltage across it exceeds the Vf. This voltage is
usually small , perhaps 2Vf and depends on the diodes materials of construction.
The diode itself follows Ohms Law V=IR (or E=IR) when the voltage is above
the Vf.
Lets see how this works:
Put a common LED across a 12V source, and the current will be extremely large,
since 12V/~0 Ohms=Huge current. Now we have to understand that the battery or
source of power and the wires, etc. have some small resistance, so the current
is not quite infinite, but some very large value. (Ka-blam.) But the LED lowers
the voltage by its forward voltage (here 2 Vf). Even so 12V-2 Vf =10V and 10V/~0
Ohms is still huge.
So we have the bright idea that we can simply use 6 x 2 Vf LEDs, we can get:
12V-2Vf -2Vf -2 Vf -2Vf -2 Vf -2Vf = 0 volts/~0=hmmmmm. The LEDs in this case are
each at the voltage where they can almost light. But this is no good for anybody.
If we use 5 x 2V LEDs, then 12V-2V-2V-2V-2V-2V= 2V/~0=Current (probably
excessive) that is dependent only upon the residual resistance and true source
voltage of the circuit. Furthermore it depends on the LEDs Vf being exact and
independent of all outside influenceswhich it is most certainly not. Additionally
if you build a circuit where the LEDs are on the hairy edge of lighting,
dimming them is problematic.
What to do, what to do? Add a resistor to the string of LEDs If we use 5 x 2Vf,
and want a current of 30 mA, then 12V-2Vf -2Vf -2Vf -2Vf-2Vf =2V/.030A=67 Ohms.
This 67 Ohm resistor swamps any likely source resistance (which is usually
just a few Ohms), and doesnt allow for much slump in the voltage source (10V and
these LEDs are off) The resistor needs to be a wattage of at least I^2 X R=0.030A
X 0.030A X 67 Ohms=0.06 Wattsvery small in this case but the wattage calculation
of LED current-limiting resistors is important and frequently neglected.
Additional note: The voltage source can be as large as one likeseven kilovoltsbut
the resistor must be suitable for the voltage.
Additional note: Vf is not a parallel-is-lower type of characteristic. Vf values
sum in series, but do not sum in parallel, exactly like batteries! This makes
putting banks of LEDs in series and parallel together a practical approach.
Conclusion: When using LEDs in a string, the current limiting resistor must have
a high enough value to make ignoring the source resistance reasonable, and allow
for dimming capability headroom as desired.
Eric M. Jones, Perihelion Design, 07/30/12
--------
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=379593#379593
Message 4
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| Subject: | Re: Using LEDs in Series |
>
> LEDs in series is not as potentially problematic as incandescents in
> series. Incandescent bulbs are relatively delicate and short lived as they
> are a heater that emits light. The life of an LED that is driven at it's
> rated current (not over driven) and properly heat sinked (in the case of
> high brightness LEDs >1W) is tens of thousands of hours. In the developing
> industry of SSL (solid state lighting) it is common practice to series
> connect LEDs. In most cases this is preferred as the current is held
> constant and the voltage is varied depending on the number of LEDs in the
> string (as Eric has described). If you are driving high output devices >1W
> you will need to use a constant current driver. You will find that as you
> limit current on these higher output devices a limiting resistor will
> dissipate considerable power, much more than the LED.
>
Chris Stone
RV-8
Newberg, OR
>
> > This raises a good question: is it okay to light a strip of LEDs by just
> wiring them in series in a quantity such that each LED sees the appropriate
> voltage drop? This would seem to eliminate the (admittedly small) energy
> loss from heating up resistors. On the other hand, failure of one LED would
> darken the whole string. Thoughts?Dan
>
> <snip>
>
Message 5
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| Subject: | Re: Using LEDs in Series |
One last thing:
In many cases a simple current-regulated power supply is all you need to drive
series/parallel LEDs. This also has the advantage of being essentially noise free.
I sell an LED tail light where I used a tiny switching power supply but never
could stop the noise (Bob N. has a solution to this...but it is a little
complicated) The problem was particularly bad because the LED is in the tail...and
frequently so are the antennas. So I changed to a simple current-regulated
supply that is a little inefficient, but stone-silent.
I have no doubt that there are switching supplies that are very quiet, too.
--------
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=379610#379610
Message 6
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| Subject: | HUD for GA aircraft |
Just a fyi about an interesting blurb I saw in a gizmag email today
about a new heads up display for GA aircraft. I have no connection with
them, just passing along the info.
PAT Avionics shows G-HULP heads-up-display system for recreational aircraft
http://www.gizmag.com/pat-avionics-hud-recreational-aircraft/23477/?utm_source=Gizmag+Subscribers&utm_campaign=a4a140692e-UA-2235360-4&utm_medium=email
Jerry Sipple
Cozy MkIV project
Message 7
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| Subject: | Re: Using LEDs in Series |
Eric, a "simple current regulated power supply is nothing more than an acti
ve circuit providing variable resistance to keep the current constant while
the applied voltage fluctuates. -This means that power is dissipated in
its "variable resistance circuit, usually a transistor in its active state.
A switched current regulator, on the other hand, keeps the switching transi
stors in their on-off states with power dissipated mostly during the switch
ing time when they're in the active state. -This has the disadvantage of
generating transients and harmonics which may bleed into the wrong places.
Do you have a magical circuit that somehow doesn't generate RF interference
and also doesn't dissipate very much power?
Thanks.
Henador Titzoff
--- On Mon, 7/30/12, Eric M. Jones <emjones@charter.net> wrote:
From: Eric M. Jones <emjones@charter.net>
Subject: AeroElectric-List: Re: Using LEDs in Series
et>
One last thing:
In many cases a simple current-regulated power supply is all you need to dr
ive series/parallel LEDs. This also has the advantage of being essentially
noise free. I sell an LED tail light where I used a tiny switching power su
pply but never could stop the noise (Bob N. has a solution to this...but it
is a little complicated) The problem was particularly bad because the LED
is in the tail...and frequently so are the antennas. So I changed to a simp
le current-regulated supply that is a little inefficient, but stone-silent.
I have no doubt that there are switching supplies that are very quiet, too.
--------
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=379610#379610
le, List Admin.
Message 8
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Bob: Thanks for all the good info that comes thru. I would like to
purchase your book but cannot locate how to do it. Could you help thanks.
Gordon
Message 9
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| Subject: | Re: Using LEDs in Series |
> Do you have a magical circuit that somehow doesn't generate RF interference and
also doesn't dissipate very much power? Thanks. Henador Titzoff
If I did, I wouldn't be posting here. I'd have my jet parked on my private Caribbean
Island. But I'd invite everybody over for a Margarita.
Seriously, there are two kinds of power supplies...Digital and Analog. ALL the
digital stuff makes noise, ALL the analog stuff dissipates power. Is there some
magical in-between*? Probably not, but the digital stuff can be made arbitrarily
close to noise-free with really good design. This usually involves knowing
what frequency spectrum you can use for switching...something that won't interfere.
(*Filters are almost all analog...but here I mean the active regulation element)
--------
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=379626#379626
Message 10
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| Subject: | Re: HUD for GA aircraft |
The big deal about HUDs is that they are focused at infinity with some
fancy (heavy) optics. That way you look out the window and everything is
in focus, data/target/bad guys laid on top of the scenery. This looks
like a see through LCD (or similar), focussed on the plate. I'm not sure
that would of huge benefit as you would be continually be re-focussing
between the plate and the scenery. So $5000 for something that is only
of real use when attacking those pesky ground targets, and then
requiring a lot of focus shifting. It would be interesting to know what
kind of lag there is between the world moving and the depiction on the
glass responding - if it is more that 100ms (that is 0.1 seconds) then
it is too slow to be of much use and will only be a hindrance.
Thanks for posting.
Peter
On 30/07/2012 19:45, Jerome Sipple wrote:
> Just a fyi about an interesting blurb I saw in a gizmag email today
> about a new heads up display for GA aircraft. I have no connection
> with them, just passing along the info.
>
> PAT Avionics shows G-HULP heads-up-display system for recreational
> aircraft
>
> http://www.gizmag.com/pat-avionics-hud-recreational-aircraft/23477/?utm_source=Gizmag+Subscribers&utm_campaign=a4a140692e-UA-2235360-4&utm_medium=email
>
> Jerry Sipple
> Cozy MkIV project
>
>
> *
>
>
> *
Message 11
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At 03:24 PM 7/30/2012, you wrote:
>Bob: Thanks for all the good info that comes thru. I would like to
>purchase your book but cannot locate how to do it. Could you
>help thanks. Gordon
My website at
http://tinyurl.com/89kaepk
. . . has an expanded information set that
augments the book. There's also an catalog/
order page at:
http://tinyurl.com/36e7ddd
where you can enter an order for the book.
Thanks for asking.
Bob . . .
Message 12
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| Subject: | Re: Latching Relay Redux |
I received this email today from Chuck (quoted below) in reference to my circuit
"Contactor PWM.pdf " to reduce contactor holding current.
http://forums.matronics.com/download.php?id=32370
> Hello Joe
> I built the circuit with one change. I replaced R1 with an adjustable 0-25k ohm
pot. Works great, just dial in the PWM for the right duty cycle with R1 for
the particular contactor being used.
> Thanks Chuck
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=379655#379655
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| Subject: | Re: Using LEDs in Series |
Therein lies another problem, Eric. For a switching regulator (digital) tha
t is "noise free with really good design," you say that it involves knowing
what frequency spectrum you can use for switching ... something that won't
interfere. -As diverse as our airplanes are, with several systems and wi
th ubiquitous installation techniques and paths, how does one design a nois
e free switching regulator? -The only way I can think of is to design it
with passive filtering and packaging methods such that radiated and conduct
ed EMI is reduced to something extremely low. This would also involve exten
sive testing to verify the low EMI. That kind of design and testing would c
ost a pretty peso.
Seems to me the safest way to go is an active linear regulator with a suffi
cient back plate to dissipate the heat.
Henador Titzoff
--- On Mon, 7/30/12, Eric M. Jones <emjones@charter.net> wrote:
From: Eric M. Jones <emjones@charter.net>
Subject: AeroElectric-List: Re: Using LEDs in Series
et>
> Do you have a magical circuit that somehow doesn't generate RF interferen
ce and also doesn't dissipate very much power? Thanks. Henador Titzoff
If I did, I wouldn't be posting here. I'd have my jet parked on my private
Caribbean Island. But I'd invite everybody over for a Margarita.
Seriously, there are two kinds of power supplies...Digital and Analog. ALL
the digital stuff makes noise, ALL the analog stuff dissipates power. Is th
ere some magical in-between*? Probably not, but the digital stuff can be ma
de arbitrarily close to noise-free with really good design. This usually in
volves knowing what frequency spectrum you can use for switching...somethin
g that won't interfere.
(*Filters are almost all analog...but here I mean the active regulation ele
ment)
--------
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=379626#379626
le, List Admin.
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