Today's Message Index:
----------------------
1. 01:17 AM - Rochester dual indicator (bouguy)
2. 03:19 AM - S700 Switches (ianwilson2)
3. 05:36 AM - Re: S700 Switches (Robert L. Nuckolls, III)
4. 05:40 AM - Re: Rochester dual indicator (Robert L. Nuckolls, III)
5. 06:05 AM - Trim noise in Audio speaker ()
6. 06:21 AM - Re: Bridge diodes VS Schottky ()
7. 06:35 AM - Re: S700 Switches (John Ciolino)
8. 07:19 AM - Re: S700 Switches (Bret Smith)
9. 07:40 AM - Z13/8 questions (Jim McBurney)
10. 08:06 AM - Re: Trim noise in Audio speaker (Robert L. Nuckolls, III)
11. 08:14 AM - Re: Bridge diodes VS Schottky (Robert L. Nuckolls, III)
12. 08:43 AM - Re: Z13/8 questions (Robert L. Nuckolls, III)
13. 12:49 PM - Sleep well tonight, our government is AWAKE! (Robert L. Nuckolls, III)
14. 02:09 PM - Re: Sleep well tonight, our government is AWAKE! (Michael W Stewart)
15. 05:05 PM - Re: Cabbages and kings . . . (Eric M. Jones)
Message 1
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Subject: | Rochester dual indicator |
hi ,
i have a Rochester dual indicator , Oil temp and Oil Press ,
Cessna Part N S3279-1 coming from a 28volts Skyhawk .
i would like to use it but as i have no Parts catalog , am not
able to determine probe and sender references .
is somebody able to help me ?
thanks a lot ,
Guy , Barracuda builder .
:(
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=192612#192612
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Hi All,
I've searched the B&C site as well as Bob's AeroElectric site to try and find some
schematics that will show me the pin numbers of the S700 series of fast-on
switches, but without any luck. Can someone please point me in the right direction,
or can I rely on Figure 11-11 of Bob's 'Switch Ratings, What's it all
Mean?' article for my 1-3 and 2-10 switches?
Many thanks.
Ian
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=192614#192614
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Subject: | Re: S700 Switches |
At 03:13 AM 7/14/2008 -0700, you wrote:
>
>Hi All,
>
>I've searched the B&C site as well as Bob's AeroElectric site to try and
>find some schematics that will show me the pin numbers of the S700 series
>of fast-on switches, but without any luck. Can someone please point me in
>the right direction, or can I rely on Figure 11-11 of Bob's 'Switch
>Ratings, What's it all Mean?' article for my 1-3 and 2-10 switches?
>
>Many thanks.
Yes.
Bob . . .
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Subject: | Re: Rochester dual indicator |
At 01:13 AM 7/14/2008 -0700, you wrote:
>
>hi ,
>
>i have a Rochester dual indicator , Oil temp and Oil Press ,
>Cessna Part N S3279-1 coming from a 28volts Skyhawk .
>
>i would like to use it but as i have no Parts catalog , am not
>able to determine probe and sender references .
>
>is somebody able to help me ?
>
>thanks a lot ,
>
>Guy , Barracuda builder .
Man! That goes back a few years. I'll see if any of
my old friends at Cessna can pull the S-sheet for me
on the gage cluster. I think it calls out the
companion parts and their Cessna standard number.
Those documents will at least speak to performance
of the senders. I think the OilT is a custom thermistor
and OilP is a carbon pile pressure to resistance
transducer. They all had common Rochester source
numbers from the automotive industry. The BIG question
will be whether or not they're still made as automotive
spares.
I'll see what I can find out for you.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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Subject: | Trim noise in Audio speaker |
All,
I have a cabin mounted speaker setup which is fed off of a Garmin 340.
When I'm listening to the radio and run any of the trim motors (Ray
Allen), I get feedback noise through the audio system. Is there any way
to filter this or otherwise eliminate it?
Thanks
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Subject: | Bridge diodes VS Schottky |
I have never understood all this squabble about the lowly bridge diode
except to provide more free advertising for the Schottky. I constantly
run 15-20 amps through my bridge diode and except for initial loading,
the temp on the diode isn't enough to warm the legs on a fly. Use the
heat sink and good 10 gauge wire for the short jumpers between the
buses. Since the max limit is 25 Amps (momentary), one may easily
control the load served. I have found not value in spending the big
bucks on the Schottky.
On the other hand my fancy Garmin stack puts out enough heat such to
warrant adding a fan and a plenum to one side with a scat tube to warm
the cabin on fall days.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L. Nuckolls, III
Sent: Sunday, July 06, 2008 12:21 PM
Subject: Re: AeroElectric-List: Bridge diodes VS Schottky
--> <nuckolls.bob@cox.net>
At 08:03 PM 7/5/2008 -0700, you wrote:
>
>WOW Bob, Its my turn to point out you have misunderstood my points in a
>few cases
>
>For example
>sniped to shorten the post
>
>> . . . you've mis-interpreted the discussions. Nobody from
>> this side of the list-server has ever shouted at anyone . . .
>
>Not you, but others have suggested there is no point to Eric's
>recommendation, Shout is my opinion perhaps not yours. Shouting down is
>in my opinion a series of comments indicating that Eric's suggestion
>was not needed along with suggested Bridge diode Vf well below worst
>case values which may not be repeatable by other builders. Its
>important to go much farther in parts selection, even suggestions years
>old. Bridge diodes were useful back in the days of single battery and e
>bus loads of 2-3 amps. Its important to update and or put real limits
>on the use of Bridge diodes. Most thought the Bridge diode was a 25 amp
>diode until Eric pointed out it was really a 12.5 amp diode. Further
>showing two in parallel is understood to non electrical engineers as
>splitting the current which is better? right :-)
'Better' needs to be quantified under the design goals. My
studies to be published soon show that the lowly bridge is
just fine as an e-bus feeder up to and including Z-13/8 with
an 8A continuous e-bus load and is not at risk of failure
for transient loads of 2x that amount.
>> Exactly! The superior performance of the Schottky diode is
>> not and never has been in question. What WAS in question was
>> the offering of an alternative to the lowly silicon rectifier
>> with equal dearth of data to support the promotion of a part
>> that was more expensive, had to be acquired from a source perhaps
>> less convenient than Radio Shack and was no easier to install.
>
>> Further, this had nothing to do with me, B&C or even Radio Shack
>> making a buck on the occasional sale of a bridge rectifier. When
>> the "new and improved" product came to the market, the lack of
>> data left many folks who already had bridge rectifiers installed
>> wondering if they'd done a bad thing . . . "Gee, should I rip it
>> out and put in the really good part?"
>
>The Schottky diode has decades of industry wide documentation in
>support of its superior performance and the diode bridge is simply not
>used in any recent design application for DC circuit controlling as we
>use it in your excellent application suggestions. Further I never
>suggested or implied anyone was making a buck on any part ever! Where
>did that comment come from???
Forgive me. There seemed to be a question about the 'narrowness
of suggested parts' when only AEC/B&C catalog numbers were cited
in the documentation and writings on the website.
> As for should I rip it out? Without more information such as heat
>loss, battery charging etc the answer is maybe it depends. PS the new
>and improved product existed in the 1980's Also my local RS store does
>not carry these parts.
>
>Today's circuits include battery charging as several posters have
>mentioned, another had stated his bus load was 8 amps and the bridge
>recommended attached to a simple bracket is not a good solution at
>higher currents. As many have clearly interpreted the recommended
>bridge it will not meet these design goals.
The data will tell . . .
<snip>
>> One COULD quibble over what the design goals for achieving "full
charge".
>> Clearly, if you have say 24 hours to wait, 13.8 volts will top off
a room
>> temperature lead-acid battery of any pedigree . . . but as a
practical
>> matter, we'd like to get our ship's battery topped off in the first
few
>> minutes of flight and under variety of temperatures. So we force
the
>> battery to suffer acceptable indignities by boosting the bus
voltage
>> under a perfectly rational idea that the goal is to store energy to
>> meet design goals . . . not squeeze a few extra flights of service
>> life out of a battery that is difficult to qualify. But yes, if one
>> chooses to go the diode isolator route for batteries, the Schottky
>> device offers a demonstrable advantage over silicon junction
>> rectifiers. I'll point out further that your design goals for
>> incorporation of a diode were decidedly different than for normal
>> feed path steering of the e-bus power.
>
>True but as above many current list builders use the diode to charge
>the battery. Setting the alternator to 14.3V will not, in a reasonable
>time, charge a backup battery as the bridge Vf can reach nearly 1 volt
>leaving the battery terminal voltage around 13.3 V which is below a
>reasonable voltage for charging. Further if the battery is really
>discharged the charging current is likely to exceed the allowable
>bridge maximum current. I recall the delta V to charge a battery is
>0.2V per cell at room temp. This amounts to 1.2V for a 12V battery.
>Thus 13.3V charging V will eventually charge the battery to 12.1V
>hardly adequate!
No argument. This is why I've never recommended diodes for
battery isolation in favor of the lowly relay or switch
that eliminates this design issue.
<snip>
>> As a designer with decades of experience of working with
>> those breakers (knowing about their demonstrated capabilities
>> outside the guaranteed performance), I was able to
>> exploit their capabilities in ways that got some folks
>> really excited . . . for no good reason based on the physics.
>
>I understand the widespread of use of parts outside their design
>because one can usually get away with it. This is a poor excuse for
>proper design and again simply not allowed in aerospace where it must
>work with any part from any approved mfgr. In the above example there
>is no need to extrapolate as the addition of a simple series resistor
>will limit the current to specification values and not detract with the
>designs purpose or function.
No, I was "getting away" with nothing. I pointed out that
the parts in question were specified and tested to military
qualification standards that included test point that
lay far outside the bounds of the envelopes published in
the catalog data. Adding the resistor was only not
necessary, it degraded performance of the design in allowing
the ov condition to achieve higher magnitude for longer
periods of time. This WAS cleared by the manufacturers
of said devices and qualified under the watchful eyes of
my DERs and has been flying successfully on thousands of
TC and OBAM aircraft for over 20 years
<snip>
>> Exactly. And that works out to a heatsink with about 8.5C/Watt
>> thermal resistance which is NOT a very big heatsink.
>
>Not sure I agree and clearly at least a couple of bridge mfgrs disagree
>as they specify (to me) a large heatsink as noted elsewhere. However
>each case of mounting location etc is different and one needs to make a
>worst case heat sink or do the design specific analysis. Thermal
>resistance is different mounted behind the engine vs. mounted behind
>the panel vs. mounted behind the baggage. Also today some aircr4qaft
>fly well above 20,000 where convection transfer is much lower.
Don't know of many OBAM aircraft that fly at these heights . . . and
those folks are not interested in Z-13/8. As my Shop Notes will
show, there is plenty of headroom for cooling for 1/4 of the
common bridge rectifier by simply mounting it to an existing
surface of the airplane's structure. Certainly not a "small
bracket".
>> Hmmmm . . . don't know about "small bracket" . . . . I've
>> suggested any flat surface of aircraft sheet metal which is
>> generally a firewall, shelf or perhaps skin.
>
>Most firewalls are or should be SS and that is a very poor heatsink The
>skin is better but no mention of the need for heat sink grease used on
>the bracket to bridge and bracket to skin etc. Many skins are also very
>thin relative to normal heat sinks leading to high thermal resistance.
True. We'll down to the simple ideas and how they fit
together shortly.
<snip>
>> Absolutely. I've seen several battery powered systems
>> fall short of design goals because the folks forgot that
>> a battery intended to supply perhaps 5-10 amps in use
>> can DRAW several times that current while being recharged.
>
>Yes but posts stating the use of the bridge as a trickle charger were
>not challenged as not safe with the bridge diode.
Don't know about "trickle charging" . . . that's a exceedingly
vaporous term. Battery isolation for the purpose of preventing
reverse flow of battery energy into the charging source is
not a "trickle charge" and as you've noted, requires further
attention to details.
>>>Why worst case analysis? Because its not possible to know the actual
>>>parameters of the parts used by the various builders. Manufacturers
do
>>>produce worst case parts and are often sold to resellers like RS with
>>>the higher quality parts are distributed to the industry market.
>>
>> Do you have some reference to support this? In years gone
>> by there have been countless suppliers of parts to the
>> hobby electronics market that indeed offered "floor sweepings"
>> in bags. I discovered the photo-sensitivity of junction
>> transistors when devices I'd purchased as "2N3904" transistors
>> had a terrible amount of hum that disappeared when the florescent
>> light over the bench was shut off. The plastic was not quite
>> as opaque as one might wish for a "real" 2N3904.
>
>I am not talking about out of spec parts. Worst case but meeting
>specification. Today parts are generally automatically tested and
>binned based on performance and selected and sold at a higher price to
>manufacturers.
???? Okay. So when I purchased a device from Radio Shack with
Fairchild's brand and part number on it, what concerns needed
to be assuaged?
>> However, the real cost of good parts has become so small
>> compared to all the other costs of distributing and marketing
>> that there is little value in spending labor to create a
>> separate product stream for sub-standard parts. Further, the
>> idea that sub-standard parts is even exist is suspect. Modern
>> semiconductor houses have so many process checks in place along
>> the assembly line that sub-standard parts are going to be
>> pitched long before they're put into final packages and marked
>> with the manufacturer's brand and part-number.
>
>I never stated sub standard parts I did say parts that were worst case
>which in this discussion had the max Vf for example. See comment just
>above your reply There is no special labor today, its 99% automated
>today. A given production run generally has a very tight distribution.
>Thus one run may produce 99% parts that are within 1% of max and
>another run may produce most parts that are 25% better than max. The
>better parts are often selected for higher performance requirements.
But once branded, date coded and identified as to part number,
of what value is any discussion on production line yields?
>There is a HUGE problem with remarked and parts made with different Die
>current plaguing the industry. Its bit even major manufacturers. This
>is a wide spread discussion in industry pubs this year and its
>apparently getting to be a larger issue as more and more parts are sub
>standard or not even the correct die inside.
But you can buy a bogus part from anybody, why pick on Radio Shack?
<snip>
>>>Availability? Its strange to me that the availability of the bridge
>>>at
>>>RS is promoted but many of the recommended switches are only
available
>>>thru B&C.
>>
>> I "promote" selection of parts adequate to the task
>> with some notion of $time$ expended to acquire those
>> parts. A $1.50 switch from the store is no bargain
>> if you hop in the car and drive 7 miles to buy it . . .
>> while saving your $5.00 switch in the drawer for a
>> "more demanding" task.
>
>My point is there are special contact/switching configurations not
>normally available anywhere to the normal builder other than you then,
>and now B&C. I would suggest you consider electrical redesign and
>restrict the switches to the commonly available contact configurations.
>Not all builders want to use large bat handle toggles but other style
>switches are not available in the special contact configurations..
Whoa! I am not in the business of specifying any parts
to anybody. This is the OBAM aircraft community we're
writing for here. Our mission as teachers and mentors
is to GUIDE the neophyte builder in crafting a failure
tolerant system with the lowest cost of ownership. If
we do our jobs well, it matters not if the switches
are Honeywell or O'Rilley autoparts.
<snip>
>My point was specific towards some of you specified switches that
>simply are not stocked or made in other mechanical configurations. I
>know as I have looked for myself and others who wanted to use that
>specification switching function but not the large bat handle actuator.
Cite examples. I believe all the parts called out on my drawings
and in my writings are offered by B&C in Carling toggles at
attractive
prices. It is beyond the scope of my mission to throw a wide net
into the switch marketplace with some idea that I'll cover the
design goals of all builders.
<snip>
>> This discussion has never been about cost of parts.
>> It has always been about selection of parts adequate
>> to the design goals with the minimum total expenditure
>> of $time$ to select, acquire, install, and maintain
>> those parts.
>
>I only pointed out there is no significant cost difference in the big
>picture and there is significant performance improvements to many
>builders. Today the cost of part acquation using the internet is lower
>cost that a auto trip to RS. Mouser is a good source for example and
>they will special order if the mfgr makes it. Shipping now is lower
>cost than auto gas and in many cases the internet delivers a no sales
>tax order.
No argument. And if you have specific recommendations to
make to any builder with respect to the selection and
procurement of any part, this List-Server is the place
to make that knowledge known. But please be specific
and support it with your deductions based on the simple-
ideas (physics, style, cost-of-ownership, preferences,
etc.) But to get out a broad brush and painting this
Shottkey vs. Silcon discussion with yet another color
is not productive.
>> In situations where the design goals were changed
>> (like battery isolation, and boss-hog e-bus loads)
>> then some re-evaluation of suggested parts is in
>> order. I've take data in the chamber on a variety
>> of diodes, done the stress tests to ascertain thermal
>> resistance of the parts and done all the photographs.
>> Measured the practical thermal resistance of small
>> sheets of aluminum.
>
>The problem with testing parts is the testing does not prove equivalent
>parts will perform the same way. Testing in the aerospace industry is
>only done as a proof of concept and only after a detailed design. Then
>the design analysis NOT the test results are used for production.
>Repeatable testing is only a valid statement using the exact same parts
>over and over.
>
>The design requirements have changed and its been several years since I
>noticed battery charging and higher e bus currents on your group or in
>the "book". It would have been helpful had there been some original
>limits defined in the "Book" regarding the use of bridge diodes as one
>example
You're making this MUCH more complicated than it needs
to be. This "worst case" canard has been tossed into
the List discussions many times over the years. I object
to and will vigorously resist the notion that we should
take cues from Boeing or NASA in the studies surrounding
the selection and application of parts.
We are not building revenue generating machines or spacecraft.
FAILURE TOLERANCE is the design goal. Our demands on
part reliability is in a totally different world from
the "big guys". We can and should ASSUME that every
part we install is going to fail at some point in time.
For folks who are following this thread, I'll refer them
to a series of 7 articles on the website that pop up under
a search for "failure tolerance". We can write volumes
of esoteric discussion on worst case, fault trees,
and 10 to the minus bizillion failure rates. This is
the mind-set that has driven the cost of a C-172 totally
out of reach for most folks who would like to own
an airplane . . . In the OBAM aircraft community
we can toss all that bilge in favor of building
systems that are not unsafe in spite of failures.
Failures that are easy to upgrade as needed so
that they don't repeat.
<snip>
>> Just need some time to put it all together into a
>> set of Shop Notes that speaks to the BIG PICTURE
>> when it comes to making any heat generating part
>> perform to design goals. Just understand that the
>> simple-ideas that support these discussions have
>> almost nothing to do with the additional cost
>> of a Schottky versus silicon-junction rectifiers.
>
>I agree and that is why I never have considered bridge diodes since
>years ago far better Schottky diodes were available. In my example I
>illustrated the best currently available schottky, much lower cost
>schottky diodes are also available if one only wants double the
>performance. Today and 15 years power Schottky diodes were available
>that were insulated bolt down.
. . . that was your well considered choice. I believe we've
done the best we know how to do in framing the discussion
so that it benefits our readers more than it confuses them.
>You are doing an incredible job helping the masses, but you seem to
>over react to comments that intend to improve and or update the design.
>There are many of us with knowledge of more modern parts that in our
>opinion a large improvement to your evolving designs
Thank you.
I don't think I over react . . . I'm always for value-added
"updates" and "improvements" but sometimes the best way
to drive a nail is with a hammer. Now, if you need to make
a living by the using thousands of nails per day,
a nail-gun or even an automatic machine is called for
as a means by which $time$ is better utilized. All
of our OBAM aircraft brothers have hammers.
My shop walls are covered in drawers and bins and
drawers . . .
http://aeroelectric.com/Pictures/Misc/Shop.jpg
http://aeroelectric.com/Pictures/Misc/Shop_1.jpg
http://aeroelectric.com/Pictures/Misc/Shop_2.jpg
in those drawers you'll find parts I've had for 40
years . . . and micro-processors and non-contact
magnetic rotary position sensors that are the latest that
the industry has to offer.
Any of those parts may find their way into a recipe for
success if found adequate to the task. Things are
not updated for the sake of being the "most improved"
especially if failure tolerant design makes the
investment of $time$ to improve problematic and
arbitrarily shuts out some economical sources of
supply.
Thank you for your $time$ and insight participating
in this discussion. It has been useful for me and
no doubt for some of our readers.
Bob . . .
Message 7
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Subject: | Re: S700 Switches |
Ian,
Try this:
http://www.aeroelectric.com/articles/Carling_Micro/Carling_Micro.pdf
John Ciolino
RV-8
----- Original Message -----
From: "ianwilson2" <ianwilson2@hotmail.com>
Sent: Monday, July 14, 2008 6:13 AM
Subject: AeroElectric-List: S700 Switches
> <ianwilson2@hotmail.com>
>
> Hi All,
>
> I've searched the B&C site as well as Bob's AeroElectric site to try and
> find some schematics that will show me the pin numbers of the S700 series
> of fast-on switches, but without any luck. Can someone please point me in
> the right direction, or can I rely on Figure 11-11 of Bob's 'Switch
> Ratings, What's it all Mean?' article for my 1-3 and 2-10 switches?
>
> Many thanks.
>
> Ian
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=192614#192614
>
>
>
Message 8
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Subject: | Re: S700 Switches |
Attention! The Carling switch terminal numbering is (in the below document)
is different than the Figure 11-11 in "Switch Ratings, What's it all Mean"
document....
Bret Smith
RV-9A "Canopy"
Blue Ridge, GA
www.FlightInnovations.com
----- Original Message -----
From: "John Ciolino" <johnciolino@comcast.net>
Sent: Monday, July 14, 2008 9:29 AM
Subject: Re: AeroElectric-List: S700 Switches
> <johnciolino@comcast.net>
>
> Ian,
>
> Try this:
>
> http://www.aeroelectric.com/articles/Carling_Micro/Carling_Micro.pdf
>
> John Ciolino
> RV-8
>
>
> ----- Original Message -----
> From: "ianwilson2" <ianwilson2@hotmail.com>
> To: <aeroelectric-list@matronics.com>
> Sent: Monday, July 14, 2008 6:13 AM
> Subject: AeroElectric-List: S700 Switches
>
>
>> <ianwilson2@hotmail.com>
>>
>> Hi All,
>>
>> I've searched the B&C site as well as Bob's AeroElectric site to try and
>> find some schematics that will show me the pin numbers of the S700 series
>> of fast-on switches, but without any luck. Can someone please point me
>> in the right direction, or can I rely on Figure 11-11 of Bob's 'Switch
>> Ratings, What's it all Mean?' article for my 1-3 and 2-10 switches?
>>
>> Many thanks.
>>
>> Ian
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=192614#192614
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
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Bob,
I'm designing the electrical system for my Zenith CH801 based on Z13/8. Two
questions:
1. Would it be an advantage to use the B&C LR3 regulator (a.l.a. Z13/20)
rather than the "generic Ford", and why or why not?
2. In rev. P you have interposed a relay in the E-bus alternate feed line.
What's your reason for this? It seems to be another single point of failure
in a simple circuit.
I'm attaching my modified drawing. Comment on it if you wish. Thanks.
Blue skies and tailwinds
Jim
CH-801
DeltaHawk diesel
Augusta GA
90% done, 90% left
Message 10
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Subject: | Re: Trim noise in Audio speaker |
At 09:02 AM 7/14/2008 -0400, you wrote:
>
>All,
>I have a cabin mounted speaker setup which is fed off of a Garmin 340.
>When I'm listening to the radio and run any of the trim motors (Ray
>Allen), I get feedback noise through the audio system. Is there any way
>to filter this or otherwise eliminate it?
Sure. Start off with a capacitor wired directly across the
motor leads (I presume they're still both white). Refer
to schematic at:
http://www.aeroelectric.com/PPS/Flight/Trim/PitchTrim.pdf
It's not common to have noise issues with these actuators.
Let's assume the noise is radiated first. Try the .22 uF
capacitor first 272-1070. Try the pair of 272-1436 if
the first doesn't work. These need to be tied into the harness
as close as practical . . . 2-3 inches outside actuator
housing.
Please let us know the results of your experiments.
If the caps don't get it by themselves, we'll ratchet
up a notch.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 11
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Subject: | Bridge diodes VS Schottky |
At 09:18 AM 7/14/2008 -0400, you wrote:
>
>I have never understood all this squabble about the lowly bridge diode
>except to provide more free advertising for the Schottky. I constantly
>run 15-20 amps through my bridge diode and except for initial loading,
>the temp on the diode isn't enough to warm the legs on a fly. Use the
>heat sink and good 10 gauge wire for the short jumpers between the
>buses. Since the max limit is 25 Amps (momentary), one may easily
>control the load served. I have found not value in spending the big
>bucks on the Schottky.
>
>On the other hand my fancy Garmin stack puts out enough heat such to
>warrant adding a fan and a plenum to one side with a scat tube to warm
>the cabin on fall days.
It's a subtle thing that touches on two issues. One is
voltage drop that goes to performance of downstream appliances.
The other is heat generated from the current voltage drop
product that must be considered with respect to ratings
of the diode in question. I'm working on a comic book that
speaks to the whole thermal management issue and heat sinks
in the electronics business.
For my own purposes, it wasn't an issue of dollars. I
was attracted to the PACKAGES for bridge rectifiers
that made it EASY for the neophyte builder to mount,
wire and heat-sink the device. There's a constellation
of diode products that would do the job electrically
assuming ratings limits are observed in each case.
I welcome any discussion that adds to the collective
knowledge of our readers . . . but object vigorously
when specific products are touted based on poor
to non-existent examination of the details.
I've got nothing against or for Schottky vs. Silicon
Junction devices. I stock and use both. But marketing
hype that exploits the ignorance/fears of potential
customers will continue to be identified for what it
is.
By the way, it's a really good idea to trim the previous
postings from your reply unless you're referencing
specific portions in your response. Helps keep the
archives from being stuffed with repeat data.
Bob . . .
Message 12
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Subject: | Re: Z13/8 questions |
At 10:35 AM 7/14/2008 -0400, you wrote:
>Bob,
>
>I'm designing the electrical system for my Zenith CH801 based on Z13/8. Two
>questions:
>
>1. Would it be an advantage to use the B&C LR3 regulator (a.l.a. Z13/20)
>rather than the "generic Ford", and why or why not?
These are ARCHITECTURE drawings . . . you can consider ANY alternative
components suited to your task. Yes, the LR3 is a very capable, all-in-one
alternator controller that includes adjustable remote sensing regulation,
lv warning, ov protection in a single package. If you don't object to
the price, it's an entirely acceptable alternative.
>2. In rev. P you have interposed a relay in the E-bus alternate feed line.
>What's your reason for this? It seems to be another single point of failure
>in a simple circuit.
When we added the 8A alternator, the e-bus continuous
load capability went up to 8A, a bit high for an always
hot lead from the battery bus (tradition says 5A max
but a FUSED lead is much less likely to start a fire
than a BREAKERED lead). If you'd like to stay with the
previous architecture and fuse the alternate feed at
10A, I wouldn't have any heartburn over it. You presently
show a 15A fuse which I presume is intended to support
peak loads, I think I'd put the relay in.
>I'm attaching my modified drawing. Comment on it if you wish. Thanks.
>Blue skies and tailwinds
You need to add the resistor across the SD-8 filter capacitor
as part of the self-excitation feature.
Fusible link in the main bus feeder is not necessary.
It's unfortunate that you can't find a 12v starter
to fit your engine but the second battery arrangement
will probably work for you.
I've .pdf'ed your drawing and attached to this response
so that others on the list can see what we're talking about.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 13
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Subject: | Sleep well tonight, our government is AWAKE! |
Over the past several years I've referred to my participation
in an investigation into the failure of a couple of switch-breakers
on a Beech Baron. The part is almost exactly the same device you
can buy at Aircraft Spruce and looks like this:
http://aeroelectric.com/Pictures/Breakers/W31_1.jpg
It seems that about 80,000 switch breakers were supplied to
Beech after a production change at Potter Brumfield that
eliminated the functional equivalent of the little piece
of insulation you see upper left inside corner of the
bracket was left out. No big deal . . . sorta.
As long as the bundle of fine wires maintains continuity
between the lower arm of the switch and the frame, everything
is right with the world.
The switch has passed many mechanical and electrical life
cycle tests in the lab over the past 20+ years. Everything
was cool.
Now comes the unexpected event that all those little copper
wires no longer maintain their intended electrical continuity . . .
in switches that are seldom operated in the airplane. Deice.
Hmmmm . . . how can this be? It seems that laboratory tests
for vibration did not reveal the effects of 10-20 years
of service that with effects of corrosion, low level but
persistent vibration, and UNRELIEVED stress risers right
at the points where the braids were spot-welded to their
respective locations on the switch arm and the frame.
For all the fuss-n-bother we went to in crafting
two-crimp terminals for wires where stress risers in
the wire grip are relieved by support at the insulation
grip . . . here we have the internal components of a switch-
breaker that do not enjoy the same level of fuss-n-bother
for equally vulnerable features.
Okay, so the wires break, now what? Since current can
no longer flow between the switch arm and frame on a nice
fat copper conductor, it flows instead through the spring. If
the breaker is lightly loaded . . . like the 5 and 10 amp
applications, no big deal. However, on airplanes fitted
with electric De-Ice heaters, it's another deal altogether.
So, as you can see in the picture, P-B is now installing
an insulator between frame and spring that prevents the
spring from becoming a toaster-element in high current
situations where the braid string is broken.
Beech has been using these breaker-switches from Skippers
to Barons for a very long time. The implications of a
fleet wide AD were, shall we say, $significant$? There was
a great deal of testing and analysis to deduce
justification for a blanket AD . . . or a testing
procedure (my little 4-wire ohmmeters at:
http://aeroelectric.com/articles/grnding.pdf
and
http://www.aeroelectric.com/articles/LowOhmsAdapter_3.pdf
will easily detect a failed or nearly failed
braid jumper).
We spent considerable time justifying an opinion that the
smaller breakers (the vast majority) did not represent
a hazard. Even the large breakers, while they squirted
smoke out the panel from around the toggle handle) the
represented a very low risk of propagating into a fire.
Folks at numerous user groups including the Bonanza Society
agreed.
But today I became aware of this jewel from our ever vigilant
benefactors/protectors in Washington . . .
http://www.aeroelectric.com/Reference_Docs/FAA/2008-13-17.pdf
It's obvious that the folks who were in the position of
deciding whether or not the FAA agreed or disagreed with
lowly commoners do not have a clue as to the physics of
the matter over which they have command and control. The
problem was not an "internal short" but an open that happens
only after a lot of time in service. Other verbiage in the
FAA document suggests that the writers have no knowledge
of the physics and an excellent knowledge of the rules
upon which one bases a you-can't-be-too-safe decision.
I'll call your attention to the compliance costs analysis
on page 5 of the document. The cost to an owner-operator
to replace this $25 breaker is about $185 each on airplanes
that range from the lowly Skipper (no De-Ice installed)
to the Barons with as many as 15 such switches (I think 3 of
the 15 were high-current applications).
This little mini-seminar has important lessons for us
in the OBAM aviation community. Its a demonstration
of risk for improperly connected wires of any size even
if INSIDE a product were you're not able to inspect them.
It's a demonstration of the value of lower parts count,
simpler construction in terms of reliability. The fuse-block/
fuse/switch combination suggested in my writing could not
get much simpler, less expensive to install, or less
expensive to maintain.
Finally, it's a small insight into a growing lack of
expertise on the part of individuals who WE pay to protect
us from ourselves. Once the TC pistons have become too
expensive to own/operate, the ever growing numbers of
protectors with too little to do will be looking for
new venues to ply their skills . . . or lack thereof.
Guess where THAT's going to be?
Bob . . .
Message 14
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Subject: | Re: Sleep well tonight, our government is AWAKE! |
Even after 10+ years of watching every email on this list, I still get
educated for free everyday.
This list is one of lifes great pleasures.
The free classroom, the discussions, and yes even the banter is
entertaining.
Thanks Bob yet again for spending the time to tell your story. Great re
ad.
Best,
Mike,
do not archive.
"Robert L.
Nuckolls, III"
<nuckolls.bob@cox
To
.net> aeroelectric-list@matronics.com
Sent by:
cc
owner-aeroelectri
c-list-server@mat Subj
ect
ronics.com AeroElectric-List: Sleep well
tonight, our government is AWAKE
!
07/14/2008 03:43
PM
Please respond to
aeroelectric-list
@matronics.com
<nuckolls.bob@cox.net>
Over the past several years I've referred to my participation
in an investigation into the failure of a couple of switch-breakers
on a Beech Baron. The part is almost exactly the same device you
can buy at Aircraft Spruce and looks like this:
http://aeroelectric.com/Pictures/Breakers/W31_1.jpg
It seems that about 80,000 switch breakers were supplied to
Beech after a production change at Potter Brumfield that
eliminated the functional equivalent of the little piece
of insulation you see upper left inside corner of the
bracket was left out. No big deal . . . sorta.
As long as the bundle of fine wires maintains continuity
between the lower arm of the switch and the frame, everything
is right with the world.
The switch has passed many mechanical and electrical life
cycle tests in the lab over the past 20+ years. Everything
was cool.
Now comes the unexpected event that all those little copper
wires no longer maintain their intended electrical continuity . . .
in switches that are seldom operated in the airplane. Deice.
Hmmmm . . . how can this be? It seems that laboratory tests
for vibration did not reveal the effects of 10-20 years
of service that with effects of corrosion, low level but
persistent vibration, and UNRELIEVED stress risers right
at the points where the braids were spot-welded to their
respective locations on the switch arm and the frame.
For all the fuss-n-bother we went to in crafting
two-crimp terminals for wires where stress risers in
the wire grip are relieved by support at the insulation
grip . . . here we have the internal components of a switch-
breaker that do not enjoy the same level of fuss-n-bother
for equally vulnerable features.
Okay, so the wires break, now what? Since current can
no longer flow between the switch arm and frame on a nice
fat copper conductor, it flows instead through the spring. If
the breaker is lightly loaded . . . like the 5 and 10 amp
applications, no big deal. However, on airplanes fitted
with electric De-Ice heaters, it's another deal altogether.
So, as you can see in the picture, P-B is now installing
an insulator between frame and spring that prevents the
spring from becoming a toaster-element in high current
situations where the braid string is broken.
Beech has been using these breaker-switches from Skippers
to Barons for a very long time. The implications of a
fleet wide AD were, shall we say, $significant$? There was
a great deal of testing and analysis to deduce
justification for a blanket AD . . . or a testing
procedure (my little 4-wire ohmmeters at:
http://aeroelectric.com/articles/grnding.pdf
and
http://www.aeroelectric.com/articles/LowOhmsAdapter_3.pdf
will easily detect a failed or nearly failed
braid jumper).
We spent considerable time justifying an opinion that the
smaller breakers (the vast majority) did not represent
a hazard. Even the large breakers, while they squirted
smoke out the panel from around the toggle handle) the
represented a very low risk of propagating into a fire.
Folks at numerous user groups including the Bonanza Society
agreed.
But today I became aware of this jewel from our ever vigilant
benefactors/protectors in Washington . . .
http://www.aeroelectric.com/Reference_Docs/FAA/2008-13-17.pdf
It's obvious that the folks who were in the position of
deciding whether or not the FAA agreed or disagreed with
lowly commoners do not have a clue as to the physics of
the matter over which they have command and control. The
problem was not an "internal short" but an open that happens
only after a lot of time in service. Other verbiage in the
FAA document suggests that the writers have no knowledge
of the physics and an excellent knowledge of the rules
upon which one bases a you-can't-be-too-safe decision.
I'll call your attention to the compliance costs analysis
on page 5 of the document. The cost to an owner-operator
to replace this $25 breaker is about $185 each on airplanes
that range from the lowly Skipper (no De-Ice installed)
to the Barons with as many as 15 such switches (I think 3 of
the 15 were high-current applications).
This little mini-seminar has important lessons for us
in the OBAM aviation community. Its a demonstration
of risk for improperly connected wires of any size even
if INSIDE a product were you're not able to inspect them.
It's a demonstration of the value of lower parts count,
simpler construction in terms of reliability. The fuse-block/
fuse/switch combination suggested in my writing could not
get much simpler, less expensive to install, or less
expensive to maintain.
Finally, it's a small insight into a growing lack of
expertise on the part of individuals who WE pay to protect
us from ourselves. Once the TC pistons have become too
expensive to own/operate, the ever growing numbers of
protectors with too little to do will be looking for
new venues to ply their skills . . . or lack thereof.
Guess where THAT's going to be?
Bob . . .
========================
============
========================
============
========================
============
========================
============
Message 15
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Subject: | Re: Cabbages and kings . . . |
So, do I have to get in here and solve EVERYONE'S problems....Cheeeze.
My friend Paul calls me and tells me deep technical details of things of our common
interest along with his complaints about disagreements with Bob....which
I am sometimes vaguely aware of...yawn...because I read very little of Bob's tirades
because they give me the Gollywoggles. (Cripes...where DOES he get the
energy?)
Seriously--Bob is absolutely right about thousands of things, and a great help
to all who are engaged in building flying machines. He is only stone-cold-crazy-wrong
about a dozen or so...so what's the percentage here? Pretty good I'd say.
I'd recommend him.
As for me, I figured this out some time ago: I just sell my own creations to thousands
of Bob's customers who, while appreciating Bob's great skill and wisdom,
can't bear walking into a Radio Shack to buy and cripple an FWB. I have sold
many many many hundreds of International Rectifier PowerSchottkys. Nobody ever
comes back and says, "Gee, I was looking for a lower-power device with higher
losses and questionable pedigree....you know, the way they did it way back
in 1935."
My suggestion is to encourage more independent invention and really clever products
for the EA community. I don't ever intend to compete with Bob or JetPilot
or Paul M., but I value all their opinions and contributions. You bet I do.
See the attachment if you want to peek at schematic Z100 (in process). I mention
this because I am barely interested in having anybody tell me I should do it
Bob's or Paul's of JetPilot's or somebody else's way. Some will want to use parts
of Z100 in their design, and some will choose the rather dated but well tested
design Bob has spent years working on (Watch out for those dozen crazy things!).
I accept and encourage people pointing out my errors (and I do make some), but
as for personal philosophy...Hell, we all should be flying Cessnas, bubela.
When the Oakies left Oklahoma and moved to California,
it raised the I.Q. of both states."
--Will Rogers
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=192742#192742
Attachments:
http://forums.matronics.com//files/power_protector_revb_161.pdf
http://forums.matronics.com//files/leos_tale_967.pdf
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