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nuckolls.bob(at)aeroelect
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 Posted: Sun Nov 01, 2009 4:42 pm Post subject: Relays etc |
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Second, as a short cut to some thinking, I made a habit of checking
with how the auto industry wired things - you know if they had a device too
rich in current to switch alone, they used relays and the same principle
applies. I have never (well once) had to change a car relay since 1948 (and
it was corroded) so I guess my aircraft device (homebuilt) could stand it.
Bosch relays seem very reliable.
Just an idea,
An astute and accurate observation my friend. As a rule,
relays are considered to be some of the least reliable
devices in terms of failures per flight hour. Indeed
compared to transistors, capacitors and such, they are
way down on the totem pole.
So when you're working on a 200 ton ATC aircraft with
miles of wiring and tons of electro-whizzies that
get exercised 15 hrs a day for weeks at a time, one
minimizes the numbers of relays and picks them carefully.
Down-time on these aircraft is measured in thousands of
dollars per day.
In the automotive world, the cost of ownership and
magnitude of risk due to failure is much lower than
for complex aircraft. Light airplanes are certainly
higher risk but failure tolerant design can buffer
that risk.
Hence, relays need not be avoided where they make
sense. One doesn't want to put an ugly-beefy toggle
switch in right next to an ordinary 7 - 10A device
just to accommodate some heavier load. Relay buffering
is a good thing to consider . . . solid state relays
even better.
Fortunately for us, only things like pitot heat
(30A inrush), large landing lights (30-50A inrush)
and perhaps hydraulic pump motors (100A inrush)
are devices that give pause for extra attention.
Relays like this . . .
http://tinyurl.com/yhrqnkz
are designed and tested to survive under the hood
of an automobile. There are other examples in the same
family of products. They're made on totally automated
machines and are reasonably priced. Once
the system demands push much above 7A or offer
extra-ordinary inrush loads, a relay may be
an ingredient that fits your recipe for success
quite well.
Having said that, let's talk about any particular
situation where you think the relay is a potential
solution to a design goal. I about dropped my teeth
when I saw this picture the first time:
http://aeroelectric.com/Pictures/Relays/TooManyRelays.jpg
. . . and these were part of an electrically dependent
engine's ignition, fuel and controls system!
"One is good" does not morph into "21 is better."
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
[quote][b]
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N20DG
Joined: 02 Jan 2008
Posts: 61
Location: lancaster, texas
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| Posted: Sun Nov 01, 2009 7:16 pm Post subject: Relays etc |
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Try this site for a better price ie $2.49 ea
https://www.surpluscenter.com/item.asp?UID=2009110121075049&catname=&qty=1&item=11-2275
They have lots of other goodies also
Dick
In a message dated 11/1/2009 4:44:00 P.M. Pacific Standard Time, nuckolls.bob(at)aeroelectric.com writes:
| Quote: |
Second, as a short cut to some thinking, I made a habit of checking
with how the auto industry wired things - you know if they had a device too
rich in current to switch alone, they used relays and the same principle
applies. I have never (well once) had to change a car relay since 1948 (and
it was corroded) so I guess my aircraft device (homebuilt) could stand it.
Bosch relays seem very reliable.
Just an idea,
An astute and accurate observation my friend. As a rule,
relays are considered to be some of the least reliable
devices in terms of failures per flight hour. Indeed
compared to transistors, capacitors and such, they are
way down on the totem pole.
So when you're working on a 200 ton ATC aircraft with
miles of wiring and tons of electro-whizzies that
get exercised 15 hrs a day for weeks at a time, one
minimizes the numbers of relays and picks them carefully.
Down-time on these aircraft is measured in thousands of
dollars per day.
In the automotive world, the cost of ownership and
magnitude of risk due to failure is much lower than
for complex aircraft. Light airplanes are certainly
higher risk but failure tolerant design can buffer
that risk.
Hence, relays need not be avoided where they make
sense. One doesn't want to put an ugly-beefy toggle
switch in right next to an ordinary 7 - 10A device
just to accommodate some heavier load. Relay buffering
is a good thing to consider . . . solid state relays
even better.
Fortunately for us, only things like pitot heat
(30A inrush), large landing lights (30-50A inrush)
and perhaps hydraulic pump motors (100A inrush)
are devices that give pause for extra attention.
Relays like this . . .
http://tinyurl.com/yhrqnkz
are designed and tested to survive under the hood
of an automobile. There are other examples in the same
family of products. They're made on totally automated
machines and are reasonably priced. Once
the system demands push much above 7A or offer
extra-ordinary inrush loads, a relay may be
an ingredient that fits your recipe for success
quite well.
Having said that, let's talk about any particular
situation where you think the relay is a potential
solution to a design goal. I about dropped my teeth
when I saw this picture the first time:
http://aeroelectric.com/Pictures/Relays/TooManyRelays.jpg
. . . and these were part of an electrically dependent
engine's ignition, fuel and controls system!
"One is good" does not morph into "21 is better."
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
|
[quote][b]
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skywagon
Joined: 11 Feb 2006
Posts: 184
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| Posted: Sun Nov 01, 2009 9:37 pm Post subject: Relays etc |
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Dick,
Thanks for the web link.....
David
[quote] ---
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N20DG
Joined: 02 Jan 2008
Posts: 61
Location: lancaster, texas
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| Posted: Mon Nov 02, 2009 8:12 am Post subject: Relays etc |
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David
No Problem that's what we're here for
Dick
In a message dated 11/1/2009 9:38:32 P.M. Pacific Standard Time, skywagon(at)charter.net writes:
[quote] Dick,
Thanks for the web link.....
David
[quote] ---
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gordonrsmith921@yahoo.com
Joined: 06 Oct 2009
Posts: 24
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| Posted: Tue Nov 03, 2009 5:12 am Post subject: Re: Relays etc |
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Att'n: 'Lectric Bob:
You mentioned ". . . solid state relays even better."
I recall some time ago that you mentioned that you might design, build, market solid state relays. Is that still a possibility for the future?
Gordon smith
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nuckolls.bob(at)aeroelect
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| Posted: Tue Nov 03, 2009 8:25 am Post subject: Relays etc |
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At 07:12 AM 11/3/2009, you wrote:
| Quote: |
<gordonrsmith921(at)yahoo.com>
Att'n: 'Lectric Bob:
You mentioned ". . . solid state relays even better."
I recall some time ago that you mentioned that you might design,
build, market solid state relays. Is that still a possibility for the future?
Gordon smith
|
Absolutely. That design is done and tooled. At
the moment, I don't have a production facility
free. We're still knee deep in house remodeling
and shuffling of furniture between four locations.
The goal now is to have the kids in my Wichita
house over the Thanksgiving week. Give them a
few weeks to get "settled in" and I'll be training
them to take over the AeroElectric Connection
production and order fulfillment.
That will let me spend 100% of my time on development
of about a dozen new products. Here's the preliminary
data on a solid state relay.
http://www.aeroelectric.com/Catalog/AEC/9030/
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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gordonrsmith921@yahoo.com
Joined: 06 Oct 2009
Posts: 24
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| Posted: Thu Nov 05, 2009 6:08 am Post subject: Re: Relays etc |
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Bob wrote
"That will let me spend 100% of my time on development
of about a dozen new products. Here's the preliminary
data on a solid state relay."
Might one of these products be the small, light, low cost, wing leveler discussed as part of "The Right Stuff" and "The Weak Link" in July 2009?
Gordon smith
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Thu Nov 05, 2009 7:29 am Post subject: Relays etc |
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At 08:08 AM 11/5/2009, you wrote:
| Quote: |
<gordonrsmith921(at)yahoo.com>
Bob wrote
"That will let me spend 100% of my time on development
of about a dozen new products. Here's the preliminary
data on a solid state relay."
Might one of these products be the small, light, low cost, wing
leveler discussed as part of "The Right Stuff" and "The Weak Link"
in July 2009?
|
That's on the list but necessarily rather far down.
The up-front development $time$ is significant. The
manufacture calls for a significant quantity of out-
sourced materials. Further, there ARE already
very capable suppliers of similar products on the
market. A noteworthy supplier is "Mr. Autopilot"
in the person of Jim Younkin. I could not pick a
more worthy competitor.
I'll need access to a flight test airframe too.
I've considered buying or leasing something with
a prop and wings on it for that purpose. In any
case, I still think it's a righteous project with
a lot of potential. I need to make sure that any
investment WE make (my kids are being groomed to
take over AEC business interests) has a high
probability for return on investment.
In the mean time . . .
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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