Today's Message Index:
----------------------
1. 08:11 AM - Re: Re: Polyfuses (Robert L. Nuckolls, III)
2. 10:19 AM - Re: Re: Polyfuses (B Tomm)
3. 10:56 AM - Polyfuses and Lightspeed Ignition (RV Builder (Michael Sausen))
4. 11:12 AM - Re: Re: Polyfuses (Richard Tasker)
5. 11:45 AM - Re: Polyfuses and Lightspeed Ignition (Robert L. Nuckolls, III)
6. 12:44 PM - Re: Polyfuses and Lightspeed Ignition (Matt Prather)
7. 01:37 PM - AEC9033 PITS project. New URL (Robert L. Nuckolls, III)
8. 02:05 PM - Re: Re: Polyfuses (Robert L. Nuckolls, III)
9. 02:26 PM - A unique "tug" for airplanes on skis . . . (Robert L. Nuckolls, III)
10. 08:11 PM - Looking for a KA-25 Install manual (BobsV35B@aol.com)
Message 1
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At 07:56 PM 3/12/2009, you wrote:
>Sausen)" <rvbuilder@sausen.net>
>
> The source of the information got it directly from Klaus so I
> think we can at least assume it's correct for this exercise. I
> agree on the switch at the panel. I probably won't have a key
> switch so my intention is to use a normal switch for power
> control. Thanks for looking into this, let us know if you come up
> with anything on the mounting.
>
>Michael
Okay. Can't do better than that. Let's explore the polyfuse thing
closer. Maybe we can find a "real" use for these puppies
after all . . .
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 2
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When "trying to think of a good situation to use polyfuses" I don't know for
sure but seem to recall that once tripped they will not reset until the
TOTAL load is removed (switched off) presumably to let the polyfuse cool
down. Can anyone confirm this? If this is true, it is important to
consider when designing an application. You don't want to automatically
lose another powered device because of a fault in another (same as with a
breaker supplying power to more than one device). Nor do you want another
non-switchable load, or another load which is not known, on the same
polyfuse. This would make it impossible to eliminate the complete load on
the polyfuse, preventing it from being reset. Am I wrong?
I have never used polyfuses but the above is based on what I have read here
and on other lists. I still prefer a single traditional breaker (requires
manual reset) or fuse (requires manual replacement) for EACH load on the
airplane. Considering also, that they are easy to integrate into an airframe
and maintain, what's wrong with traditional circuit protection?
Bevan
Message 3
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Subject: | Polyfuses and Lightspeed Ignition |
Nothing is wrong with traditional circuit protection and I would recommend it
normally. The current use case thread for Polyfuses that I started is to address
a unique situation that traditional wire protection cannot address without
some additional risks. Read through the recent threads and you will see what
I mean. I also changed the subject line to accurately reflect the thread going
forward.
As far as them resetting only when the total load is removed, I've heard conflicting
stories on that and I'm sure Bob can set that straight once he starts
looking more closely at them. For me I'll have a switch that will remove that
load so it's a moot point and I generally only do one wire per application.
Michael
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of B Tomm
Sent: Friday, March 13, 2009 1:14 PM
Subject: RE: AeroElectric-List: Re: Polyfuses
When "trying to think of a good situation to use polyfuses" I don't know for
sure but seem to recall that once tripped they will not reset until the
TOTAL load is removed (switched off) presumably to let the polyfuse cool
down. Can anyone confirm this? If this is true, it is important to
consider when designing an application. You don't want to automatically
lose another powered device because of a fault in another (same as with a
breaker supplying power to more than one device). Nor do you want another
non-switchable load, or another load which is not known, on the same
polyfuse. This would make it impossible to eliminate the complete load on
the polyfuse, preventing it from being reset. Am I wrong?
I have never used polyfuses but the above is based on what I have read here
and on other lists. I still prefer a single traditional breaker (requires
manual reset) or fuse (requires manual replacement) for EACH load on the
airplane. Considering also, that they are easy to integrate into an airframe
and maintain, what's wrong with traditional circuit protection?
Bevan
Message 4
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You are correct in your description. Nothing wrong with either fuses or
breakers, but the individual in question has a somewhat unique situation
for which a polyfuse would provide a possibly better solution. I
believe he plans to use a separate polyfuse for each load in question.
Dick
B Tomm wrote:
>
>
> When "trying to think of a good situation to use polyfuses" I don't know for
> sure but seem to recall that once tripped they will not reset until the
> TOTAL load is removed (switched off) presumably to let the polyfuse cool
> down. Can anyone confirm this? If this is true, it is important to
> consider when designing an application. You don't want to automatically
> lose another powered device because of a fault in another (same as with a
> breaker supplying power to more than one device). Nor do you want another
> non-switchable load, or another load which is not known, on the same
> polyfuse. This would make it impossible to eliminate the complete load on
> the polyfuse, preventing it from being reset. Am I wrong?
>
> I have never used polyfuses but the above is based on what I have read here
> and on other lists. I still prefer a single traditional breaker (requires
> manual reset) or fuse (requires manual replacement) for EACH load on the
> airplane. Considering also, that they are easy to integrate into an airframe
> and maintain, what's wrong with traditional circuit protection?
>
> Bevan
>
>
>
Message 5
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Subject: | Re: Polyfuses and Lightspeed Ignition |
At 12:52 PM 3/13/2009, you wrote:
>Sausen)" <rvbuilder@sausen.net>
>
> Nothing is wrong with traditional circuit protection and I would
> recommend it normally. The current use case thread for Polyfuses
> that I started is to address a unique situation that traditional
> wire protection cannot address without some additional risks. Read
> through the recent threads and you will see what I mean. I also
> changed the subject line to accurately reflect the thread going forward.
>
> As far as them resetting only when the total load is removed,
> I've heard conflicting stories on that and I'm sure Bob can set
> that straight once he starts looking more closely at them. For me
> I'll have a switch that will remove that load so it's a moot point
> and I generally only do one wire per application.
I believe we're thinking along the same lines.
Here's a first pass at a always hot bus feeder
protection module.
http://www.aeroelectric.com/Catalog/AEC/9033/AEC9033-700-1A_Feeder_Protection_(PRELIM).pdf
Design goals:
Accommodate the unique demands driven by polyfuse packaging
(ECB mount).
No latent failures that are not pre-flight detectable.
Minimum parts count, assembly labor, bill of materials costs.
Demonstrably acceptable performance over -40 to +70C
temperature range.
I've ordered a set of polyfuses that appear correct for
this task. I'll brass-board the circuit and get some
bench tests to look at reaction times and particularly,
variability over range of operating temperatures (haven't
played with the test chamber in months!).
Given that a stock, prefabricated enclosure exists then
the only unique fabrication item is an etched circuit
board . . . and that's not a big deal. Except for the
polyfuses (which ARE inexpensive) there are no components
that are not already purchased in volume for other activities.
Bob . . .
Message 6
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Subject: | Re: Polyfuses and Lightspeed Ignition |
Parens "(" in a file name (url, link) can be problematic...
http://www.aeroelectric.com/Catalog/AEC/9033AEC9033-700-1A_Feeder_Protection_(PRELIM).pdf
Matt-
> <nuckolls.bob@aeroelectric.com>
>
> At 12:52 PM 3/13/2009, you wrote:
>>Sausen)" <rvbuilder@sausen.net>
>>
>> Nothing is wrong with traditional circuit protection and I would
>> recommend it normally. The current use case thread for Polyfuses
>> that I started is to address a unique situation that traditional
>> wire protection cannot address without some additional risks. Read
>> through the recent threads and you will see what I mean. I also
>> changed the subject line to accurately reflect the thread going forward.
>>
>> As far as them resetting only when the total load is removed,
>> I've heard conflicting stories on that and I'm sure Bob can set
>> that straight once he starts looking more closely at them. For me
>> I'll have a switch that will remove that load so it's a moot point
>> and I generally only do one wire per application.
>
> I believe we're thinking along the same lines.
> Here's a first pass at a always hot bus feeder
> protection module.
>
> http://www.aeroelectric.com/Catalog/AEC/9033/AEC9033-700-1A_Feeder_Protection_(PRELIM).pdf
>
> Design goals:
>
> Accommodate the unique demands driven by polyfuse packaging
> (ECB mount).
>
> No latent failures that are not pre-flight detectable.
>
> Minimum parts count, assembly labor, bill of materials costs.
>
> Demonstrably acceptable performance over -40 to +70C
> temperature range.
>
> I've ordered a set of polyfuses that appear correct for
> this task. I'll brass-board the circuit and get some
> bench tests to look at reaction times and particularly,
> variability over range of operating temperatures (haven't
> played with the test chamber in months!).
>
> Given that a stock, prefabricated enclosure exists then
> the only unique fabrication item is an etched circuit
> board . . . and that's not a big deal. Except for the
> polyfuses (which ARE inexpensive) there are no components
> that are not already purchased in volume for other activities.
>
> Bob . . .
>
>
Message 7
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Subject: | AEC9033 PITS project. New URL |
At 02:41 PM 3/13/2009, you wrote:
>
>Parens "(" in a file name (url, link) can be problematic...
>
>http://www.aeroelectric.com/Catalog/AEC/9033AEC9033-700-1A_Feeder_Protection_(PRELIM).pdf
Thanks Matt, I knew that . . . once.
Better URL is
http://www.aeroelectric.com/Catalog/AEC/9033/AEC9033-700-1A_Feeder_Protection_PRELIM.pdf
For all interested parties, right now this is a "PITS" project.
Pie In The Sky. Parts are on order and we'll throw some
proof of concept mud balls against the shop wall and see
what sticks.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 8
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At 12:13 PM 3/13/2009, you wrote:
>
>
>When "trying to think of a good situation to use polyfuses" I don't know for
>sure but seem to recall that once tripped they will not reset until the
>TOTAL load is removed (switched off) presumably to let the polyfuse cool
>down. Can anyone confirm this?
Correct. The devices I've ordered for a first pass look will
go into a "tripped" state at about 150 mA of continuous current
or about 2 watts of internal heat being dissipated.
>If this is true, it is important to
>consider when designing an application. You don't want to automatically
>lose another powered device because of a fault in another (same as with a
>breaker supplying power to more than one device). Nor do you want another
>non-switchable load, or another load which is not known, on the same
>polyfuse. This would make it impossible to eliminate the complete load on
>the polyfuse, preventing it from being reset. Am I wrong?
You are correct. As shown in the proposed system integration drawings, one
and only one system tied to the protection module and it needs
some means by which the circuit can be broken (switch). Of course,
you would want a switch on any ignition system anyhow.
>I have never used polyfuses but the above is based on what I have read here
>and on other lists. I still prefer a single traditional breaker (requires
>manual reset) or fuse (requires manual replacement) for EACH load on the
>airplane. Considering also, that they are easy to integrate into an airframe
>and maintain, what's wrong with traditional circuit protection?
Nothing. In this case, we're interested in feeding from an
always-hot source (battery bus) to favor an electrically
dependent engine. Always-hot feeders like to be protected
as close the source as practical. Hence some manner of
remotely mounted circuit breaker is attractive - ESPECIALLY
if your battery is back in the tail. Here we discover a
unique set of design goals that look with more favor
upon the much misunderstood and oft misapplied polyfuse.
It's even more attractive given that I have some standard
product enclosures . . .
http://aeroelectric.com/Pictures/Products/A09_Package.jpg
. . . that reduce the cost of getting these little critters
boxed up and bolted to the airplane.
I'm getting private email from folks wanting to order
this thing which is gratifying but premature. Let's
make sure we have done a good thing first. After sifting
the sands of design for polyfuses for over 20 years,
it WOULD be pretty cool to find a place where they
smoothly fit into a cost effective and well considered
design aboard an aircraft.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 9
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Subject: | A unique "tug" for airplanes on skis . . . |
See video at:
http://tinyurl.com/cg4nut
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 10
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Subject: | Looking for a KA-25 Install manual |
Good Evening All,
I find myself in need of an install manual for a very ancient piece of King
Radio equipment. It is the KA-25 Audio Amplifier.
If anyone knows where I could get a download of the manual, I would sure
appreciate having that knowledge.
I do see that Essco has it available for sale. If I can't get it for free, I
could break down and pay for it, but if anyone knows where I could download
it, I would not only save money, but could have it right now when I want
it!<G>
Happy Skies
Old Bob
AKA
Bob Siegfried
Ancient Aviator
628 West 86th Street
Downers Grove, IL 60516
630 985-8502
Stearman N3977A
Brookeridge Air Park LL22
In a message dated 3/13/2009 4:28:46 P.M. Central Daylight Time,
nuckolls.bob@aeroelectric.com writes:
See video at:
_http://tinyurl.com/cg4nut_ (http://tinyurl.com/cg4nut)
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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