Today's Message Index:
----------------------
1. 04:50 AM - Re: headset level to mic level for recording (Ron Brown)
2. 05:28 AM - Re: Crowbar OV Protection (Mike Lehman)
3. 07:44 AM - 2 mutch (Fergus Kyle)
4. 08:23 AM - Re: Points for discussion OVP//more (Paul Messinger)
5. 09:30 AM - GPS Annunciator ()
6. 11:59 AM - Re: headset level to mic level for recording (David Carter)
7. 05:21 PM - (Dan O'Brien)
8. 06:48 PM - Re: Points for discussion OVP//more (Dan O'Brien)
9. 07:09 PM - Re: gps annunciator 300xl (CardinalNSB@aol.com)
10. 09:29 PM - Re: Points for discussion OVP//more (John Swartout)
Message 1
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| Subject: | headset level to mic level for recording |
--> AeroElectric-List message posted by: "Ron Brown" <romott@adelphia.net>
>I'm not even sure if it's called a "pad" but I think it is... Here's the
>deal. I bought a digital voice recorder thing from Radio Smack with the
>intention of recording intercom & radio activity in the plane. The recorder
>has an 1/8" mic jack, and it has two "sensitivity" settings, hi and lo. I
>connected the passenger headset jack to the mic jack on the recorder, and
>not surprisingly the recorder is slightly overloaded level-wise.
I have the same set up and use an in-line volume control like this one also at
the shack. Works great!!!
http://www.radioshack.com/product.asp?catalog%5FnameCTLG&product%5Fid42-2559
Message 2
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| Subject: | Re: Crowbar OV Protection |
--> AeroElectric-List message posted by: "Mike Lehman" <lehmans@sympatico.ca>
My question refers to the VR-166 Ford type voltage regulator with an
alternator B+ to regulator terminal 'A' connection supplying alternator
field current. When the crowbar protection reduces VR terminal 'S' to under
2 volts, is the field current supply via terminal 'A' always interrupted? I
presume that the answer depends on the failure mode of the VR-166 that
caused the crowbar to 'fire' in the first place.
In other words, with the old mechanical VR-166, I have confidence that the
crowbar protection is adequate. Substituting an electronic VR-166 (with the
B+ to terminal 'A' wire, not with terminal 'A' and 'S' jumpered per Bob's
diagrams) seems to create the equivalent of an alternator with an internal
voltage regulator.
Hopefully, alternator field current via VR termimal 'A', with terminal 'S'
de-energized, is a low probability VR-166 failure mode? Anyone really know
???
Mike
Message 3
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--> AeroElectric-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
"Nice attempt at humor but you "digress" to much."
Methinks thou dost complain two much.
Ferg
Message 4
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| Subject: | Re: Points for discussion OVP//more |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
----- Original Message -----
From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Points for discussion OVP//more
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <b.nuckolls@cox.net>
>
> At 08:31 AM 3/15/2005 -0500, you wrote:
>
>>--> AeroElectric-List message posted by: Matt Jurotich
>><mjurotich@hst.nasa.gov>
. . . but assuming your system
> IS capable of producing a 250A trip current, is there
> any analysis to support the notion that this is "bad"
> for other systems in the aircraft?
>
> Bob . . .
Seems to me you have it backwards (you need to prove its compatible with
today's electronics). With today's avionics that may contain sensitive
magnetometers as well as truly electric dependent engines where dropping
below 11V at the battery can cause the engine computer to reset. Remember
all the discussion regarding electronic mags and the need for a special
battery during starting to keep the voltage high with the high starting
current typical with Lyc's etc??
Then there is the increasing use of Hall effect devices for current sensing.
One manufacturer of such devices states that a 100% over current will cause
a calibration shift. So much for accurate current measurements. The list of
potential concerns seems endless to me.
Given that I am working on a 21st century aircraft engine that is derived
from an auto engine; I have measured the starting current, including peak
currents. The current path does not go close to the instrument panel as the
crowbar CB that is mounted there does. A modern geared starter need not have
high currents like the stock Lyc starters do. Also with a smaller
displacement engine that is geared down, the power to turn it over is much
smaller. My need for measuring worst case starting current is an important
design requirement when designing solid state contactors. (The design is for
300 amps max starting while cranking and an inrush peak of more than 500
amps).
The peak starting current (with the engine I am working with) is under 200
amps (at least as measured with a 500 amp current shunt and a 400 MHz scope
system). After a peak of under 200 amps the starting current varies from 110
to 130 amps depending on compression stroke vs. power stroke in the engine.
The battery terminal voltage never drops under 11V (but the batteries are
not as you suggest but batteries designed for starting etc. ( See a 'to be
posted' discussion)
The use of old technology (Crowbars) with modern equipment can be a problem
and considering that the only supporter of a crowbar (anywhere in general
aviation aircraft?) seems to be from you so that puts the burden of proof
(that its still a good idea and safe to use) on you. A developer of a new
avionics system who only looks at certificated aircraft will not notice your
design, nor will those who also inquire with major experimental aircraft
manufacturers like Vans. I agree that protection is needed but the old
approach of using a crowbar in this way never was the best way and today is
no longer a potentially safe approach.
A realistic wiring setup (as used in a real aircraft) with a really good
battery plus a nominal CB (see CB data sheet) can produce far higher trip
currents and much longer trip times that your sample of one test shows).
More than enough to cause a reset of the engine computer depending on the
variables an individual aircraft might have. Even 250 amps is several times
the MIG or TIG welding current needed for a steel tube structure in an
aircraft. Surely you would not suggest that the avionics be installed when
doing welding in the cockpit area, but in effect, that is what the crowbar
does.
What bothers me is your the comments about how simple and low parts count it
has and has been working for 30 years. Neither has anything to do with our
concerns that my testing (and investigations) have demonstrated to me are
valid.
Also adding just one part to your crowbar could reduce the current surge to
a reasonable level and still provide the function of opening the CB. Add
another part or two and you can open the "B" lead contactor power (and open
the contactor) without resorting to the high current presently used to pop
the CB. So 3-4 parts added and no need to pop the CB and no hi current
surge. In my opinion this should have been part of the original design.
The approach Eric sells has been extensivitely tested by both of us and not
only has no current surge but has 100% of the time protection against OV
conditions (which your approach does not do; see another upcoming post on
this). Also it eliminates the heavy "B" lead contactor (In one of Eric's
approaches ).
The only down side I see to any of the above is its a change from your
traditional approach.
It may be of interest that Denso has a belt connected (not gear connected)
starter and alternator "all in one" for the modern auto where the engine is
stopped every time the auto is stopped. The web pictured device appears to
be a simple alternator but actually contains a starter also. Designed 4
years ago!
Paul
Message 5
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--> AeroElectric-List message posted by: <bakerocb@cox.net>
AeroElectric-List message previously posted by: "Vern W." <vernw@ev1.net>
<<I hope someone can steer me in a better direction with this one because
I've searched
the archives, and while there's a reference or two, I don't find any
definitive
answers: To satisfy IFR requirements using both a Garmin 300XL GPS/Comm and
SL-30 Nav/Comm,
I need to have an annunciator. No problem so far, but what I don't get
is that the MD41-1454 annunciator made for the 300XL costs almost $1600! I'd
like to think one of the inventive type in this group has come up with a way
to
do this without spending almost half the cost of the 300XL itself.
Has anyone yet come up with a schematic to do the same thing? Vern>>
AeroElectric-List message previously posted by: "Vern W." <vernw@ev1.net>
<<Jim, An annunciator may not be needed if the 300XL is the only Nav
attached
to a Nav head, but in my case, I'm going to be using the 300XL along with
the SL-30 and run them both to the GRT EFIS for Nav and HSI indication.
In this case, I'm going to have to know what signal is driving the HSI
at all times so I really do have to come up with a good annunciator.
I'm not sure, but I think Paul's installation is simpler than what I'm
doing. Vern>>
3/19/2005
Hello Vern, You are struggling with a problem that many of us have
confronted so it is worth exploring more in depth. Some comments to assist
in this exploration:
1) This is not simply an annunciator problem. When you feed the GRT EFIS (or
any CDI) from either the 300XL or the SL-30 you need an interface device
(many relays) to transfer all of the appropriate information signal inputs
from the sending devices to the receiving device (navigation indicator).
2) And you need a switch or button of some kind to activate that interface
device to tell it which source to use to drive the navigation indicator
(receiving device).
3) So the fundamental questions are: What are you using as an interface
device (a box with many relays inside) and how are you controlling that
interface device?
4) Once the interface device is chosen then you have at least three ways to
tell which source is feeding the navigation indicator:
4A) A simple two position switch - one position is labeled SL-30 and the
other is labeled 300XL. Depending upon which position the switch is in then
the interface box relays are connected to feed that source to the navigation
indicator.
4B) A push button, split illuminated switch with one half labeled SL-30 and
one half labeled 300XL that cycles the interface box between the two
sources. Which ever light is lit tells you which source is feeding the
interface box.
4C) A plain push botton switch that cycles the interface box between the two
sources and two lights on the panel, one labled SL-30 the other labled
300XL, that are fed from relays within the interface box. The appropriate
light is lit depending upon which relays are in contact.
5) Some sources for interface boxes with many relays are Perihelion Design
(thanks Eric) and Northern Airborne Technologies.
6) This subject of feeding one navigation indicator from two sources has
been discussed previously on the list if you want to go back into the
archives.
Please come back with some additional questions and thoughts on how you want
to do this.
OC
PS: The term "satisfy IFR requirements" raises the questions: Whose IFR
requirements are you referring to and where are they documented? Let's not
get wrapped around the axle of FAA / FAR requirements for installations in
standard type certificated airplanes.
Message 6
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| Subject: | Re: headset level to mic level for recording |
--> AeroElectric-List message posted by: "David Carter" <dcarter@datarecall.net>
The simplest, non-cut and solder approach is to buy 3 parts from Radio
Shack:
1) Radio Shack Y adapter: Male 1/4" plug end goes into your aircraft's
larger headset jack. Y adapter has 2 1/4" holes/jacks in top, one for your
headset's 1//4" jack and the other for
2) your new Radio Shack 1/8 to 1/4" adapter - plug big end into 2nd hole
of Y adapter;
3) Radio Shack 42-2152, 6.5' Attenuating Dubbing Cord, $3.99, which has
tiny 1/8" male/jack on each end - plug one into your video recorder's "audio
in" (or your digital recorder) and the other into the1/8 to 1/4 adapter [ 2)
above ]
It cuts the amplitude of the aircraft audo system so my video recorder audio
isn't over-driven. It works for me in the Cessna I fly wih a video
recorder.
David Carter
----- Original Message -----
From: "Ron Brown" <romott@adelphia.net>
Subject: RE: AeroElectric-List: headset level to mic level for recording
> --> AeroElectric-List message posted by: "Ron Brown" <romott@adelphia.net>
>
>
> >I'm not even sure if it's called a "pad" but I think it is... Here's the
> >deal. I bought a digital voice recorder thing from Radio Smack with the
> >intention of recording intercom & radio activity in the plane. The
recorder
> >has an 1/8" mic jack, and it has two "sensitivity" settings, hi and lo.
I
> >connected the passenger headset jack to the mic jack on the recorder, and
> >not surprisingly the recorder is slightly overloaded level-wise.
>
>
> I have the same set up and use an in-line volume control like this one
also at the shack. Works great!!!
>
>
http://www.radioshack.com/product.asp?catalog%5FnameCTLG&product%5Fid42-2559
>
Message 7
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1.16 MISSING_SUBJECT Missing Subject: header
--> AeroElectric-List message posted by: "Dan O'Brien" <limadelta@gmail.com>
>Paul wrote:
>A developer of a new avionics system who only looks at certificated
> aircraft will not notice your design, nor will those who also inquire
>with major experimental aircraft manufacturers like Vans.
Hmm... the top composite experimental (Lancair) says in its IVP
manual, its ES manual, and its recently updated Legacy manual (see
http://www.lancair-kits.com/manual_revisions/Legacy_manual_rev-0105.pdf,
p. 27-4):
"Robert Nuckolls is also an excellent reference for wiring. He
publishes a newsletter,
The AeroElectric Connection, and also contracts his services to
individual builders to design custom electrical schematics. He can be
reached at:
Medicine River Press
6936 Bainbridge Road
Wichita, Kansas 67226-1008
(316) 685-8617"
While specifics of this may be slightly off or dated (is there a
"newsletter" we don't know about beyond the website?), this is
clearly an endorsement from a pretty big player in the experimental
category. Yeah, Lancair is "small" compared to Vans, but I think it's
number one among the more "modern" composite players. FWIW.
Message 8
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| Subject: | Re: Points for discussion OVP//more |
--> AeroElectric-List message posted by: "Dan O'Brien" <limadelta@gmail.com>
>Paul wrote:
>A developer of a new avionics system who only looks at certificated
> aircraft will not notice your design, nor will those who also inquire
>with major experimental aircraft manufacturers like Vans.
Hmm... the top composite experimental (Lancair) says in its IVP
manual, its ES manual, and its recently updated Legacy manual (see
http://www.lancair-kits.com/manual_revisions/Legacy_manual_rev-0105.pdf,
p. 27-4):
"Robert Nuckolls is also an excellent reference for wiring. He
publishes a newsletter,
The AeroElectric Connection, and also contracts his services to
individual builders to design custom electrical schematics. He can be
reached at:
Medicine River Press
6936 Bainbridge Road
Wichita, Kansas 67226-1008
(316) 685-8617"
While specifics of this may be slightly off or dated (is there a
"newsletter" we don't know about beyond the website?), this is
clearly an endorsement from a pretty big player in the experimental
category. Yeah, Lancair is "small" compared to Vans, but I think it's
number one among the more "modern" composite players. FWIW.
Message 9
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| Subject: | Re: gps annunciator 300xl |
--> AeroElectric-List message posted by: CardinalNSB@aol.com
Vern:
Before I started a new business and had a head-on accident last year I was
thinking I was going to make my own annunciator panel for my Garmin 300xl.
Still thinking...
Good used 300xl can be had at very reasonable prices, I wasn't about to pay
half again just for some lights. I had a good deal of discussions on other
boards, here is what I think I know about installing it in my Cesnna Cardinal,
a certified aircraft. I emphasize that this is based only on my reading and
discussions, that I haven't found any "professionals" that agree with me on
my interpretation of the law as being a minor alteration.
I appreciate any corrections or affirmations or filling in any gaps:
1. IFR installation of gps is a "minor" mod, only log book entry required
unless it is interfaced with something "unusual", based on the AC 20-138, page
11. However, the annunciators and cdi are required in order to be in
compliance with Garmin's initial STC.
2. The cost of the "store bought" annunciator panels exceeds a good used
King ki202 or collins, I decided to directly drive the cdi and not use a relay.
I understand some ARC units will work. You need a resolver in the cdi.
3. The Garmin installation manual shows the needed 6 annunciator lights and
2 switches.
Lights 1, 2, 3, and 4 are driven by the output from the gps, through the
bulb, then to ground.
The gps controls whether the light 1, 2, 3 or 4 is energized.
Message and Arrival lights are independent of all other annunciators.
Approach Resolution Hi or Low is alternatively selected by a momentary
switch to ground a pin, but the switch is not tied to the lights.
Lights 5 and 6
Now here is what I find to be odd. The .gps is in "sequence" mode unless
the sequence pin is grounded. Not a momentary "flip flop" like the Approach
Resolution Mode, rather if its grounded its in Hold Mode and if its not
grounded its in Sequence Mode. BUT there is no driver from the gps for the lights
in either mode. Instead, the installation drawing shows a dpdt switch-in the
up position, the first pole connects power (from the bus, not the gps) to the
Sequence light then to ground and the second pole is unconnected. In the
down position, power flows to the Hold light through the first pole then to
ground and the second pole simply grounds the sequence hold pin, putting the gps
in the Hold mode.
Seems odd to me that they didn't simply output 6 annunciator lights directly
from the gps and control the 2 mode styles with appropriate switching.
4. If you use a relay to switch the cdi between gps/nav, you need another
light to indicate the source driving the cdi. I haven't researched much but
NAT advertises a relay for this. I see this on ebay often.
5. I didn't see anywhere where it listed the output voltage from the gps
for the annunciators, or that the annunciator output level varied with the
unit's own dimming function, so I assume the output is a constant 12v when
activated.
HELP PLEASE. Assuming I got the basic annunciator scheme right, how can I
easily make a multiple LED dimmer? So far, I have the face plate off of an
old annunciator which I intend to put leds behind so I can use the same white
led for each function, so the output of each annunciator will be the same with
no need to vary the voltage between the bulbs (I sure do love those blue
leds though). The problem I see is that out of the 6 lights, 2 will always be
on, sometimes 3, sometimes 4, so if I simply put a rheostat before the (common
bulb leg)ground and it is dimmed for 2 lights, and then 4 become activated,
there might not be enough voltage to light the leds. Bad if a RAIM message
is missed.
Would a circuit based on a LM 3914 be appropriate (between the gps and the
led), or can someone point me to a source for dimming multiple leds from a
common knob. Its a good thing this is a hobby... thank you Skip Simpson
but a
Light 1 is Message, driven by the Garmin 300xl, grounding the light .
Light 2 is activated by an internal relay to ground.
Light 3 is activated by an internal relay to ground.
Light 4 is activated by an internal relay to ground.
Light 5 and 6 are controlled by a dpdt switch.
Voltage goes into the dpst switch. In the up position, Light
In position up, light is on
. 4 lights are activated by
.
Message 10
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| Subject: | Points for discussion OVP//more |
--> AeroElectric-List message posted by: "John Swartout" <jgswartout@earthlink.net>
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Paul
Messinger
Subject: Re: AeroElectric-List: Points for discussion OVP//more
>There is more to life than this list :-)
Really? What's her name? ;]
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