Today's Message Index:
----------------------
1. 03:35 AM - Spike catcher diode ()
2. 04:05 AM - Switch bezel nuts (rer51)
3. 04:35 AM - Re: Switch bezel nuts (Neal George)
4. 05:23 AM - Re: Switch bezel nuts (John Ciolino)
5. 11:50 AM - Re: Re: Spike catcher diode (Robert L. Nuckolls, III)
6. 12:35 PM - Re: Spike catcher diode (Robert L. Nuckolls, III)
7. 12:51 PM - Re: Grounding question (Robert L. Nuckolls, III)
8. 02:00 PM - Contactor question (Bob Leffler)
9. 06:12 PM - Using Mono Headset in Sterio Jack (John)
10. 07:40 PM - Re: Using Mono Headset in Sterio Jack (Charlie England)
11. 07:52 PM - BMA Quitting ()
12. 08:07 PM - Re: Contactor question (Robert L. Nuckolls, III)
13. 09:24 PM - Re: Using Mono Headset in Sterio Jack (The Kuffels)
Message 1
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| Subject: | Spike catcher diode |
7/10/2009
Hello Glenn, You wrote: "I haven't decided if I'm going to use zeeners,
diodes or just replace the solenoid on some scheduled basis. I've yet to see
anything from anyone which shows how much longer (days, weeks or years) a
solenoid lasts by adding these gadgets. The problem is real, but actual life
expectancy needs to be measured to satisfy my interest."
I think that the primary purpose of a spike catcher device is to protect the
points in the switch controlling the current through the solonoid coil. The
switch points are much more fragile and susceptible to failure than the
solonoid contact points.
We frequently see reports of switch point failures, particularly in the
keyed ignition switches.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
==========================================
Time: 09:18:10 AM PST US
Subject: RE: AeroElectric-List: Spike catcher diode
From: <longg@pjm.com>
Wade,
Which approach (Zeners, Diodes or nothing) you choose is up to you. On
my website link below you can see where I employed Van's "blue" starter
diode (I have an extra contactor 'cause it's IR) which uses the same
approach. As Bob indicated I snaked the other end around the contactor
to the mounting bolt. Van's little direction sheet is quite clear -
don't deviate from it. In my case the solenoids are mounted on carbon
fiber so I use a ground back to the FG. I haven't decided if I'm going
to use zeeners, diodes or just replace the solenoid on some scheduled
basis. I've yet to see anything from anyone which shows how much longer
(days, weeks or years) a solenoid lasts by adding these gadgets. The
problem is real, but actual life expectancy needs to be measured to
satisfy my interest. If you are the typical pilot which flies 35 hours /
year it will fail from sitting around before it fails from arching.
http://2.bp.blogspot.com/_hkAHk0Xu6wo/SdymLdP-KbI/AAAAAAAAA1A/rF4p8Xvi2U
U/s1600-h/IMG_1312.JPG
Glenn
Message 2
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| Subject: | Switch bezel nuts |
I am looking for a source for the switch bezel rings. I currently have a
mix of different one and would like to standardize them. So far every
supplier say that I must buy "new" complete switches to get the rings.
Help would be appreciated. Randy R. RV9A "gittin' close"
Message 3
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| Subject: | Switch bezel nuts |
Randy - I've bought loose switch nuts from both Stein and B&C.
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of rer51
Sent: Friday, July 10, 2009 6:02 AM
Subject: AeroElectric-List: Switch bezel nuts
I am looking for a source for the switch bezel rings. I currently have a mix
of different one and would like to standardize them. So far every supplier
say that I must buy "new" complete switches to get the rings. Help would be
appreciated. Randy R. RV9A "gittin' close"
Message 4
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| Subject: | Switch bezel nuts |
Both Mouser(sp?) and Digikey sell individual bezel nuts
John Ciolino
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of rer51
Sent: Friday, July 10, 2009 7:02 AM
Subject: AeroElectric-List: Switch bezel nuts
I am looking for a source for the switch bezel rings. I currently have a mix
of different one and would like to standardize them. So far every supplier
say that I must buy "new" complete switches to get the rings. Help would be
appreciated. Randy R. RV9A "gittin' close"
Message 5
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| Subject: | Re: Spike catcher diode |
At 09:13 AM 7/8/2009, you wrote:
<emjones@charter.net>
>
>This issue has been argued here for years, so spare me your flames Bob.
Please cite any posting I've made that could be
reasonably (or even unreasonably) described as a
"flame". They're all in the archives . . . cut and
paste a direct quotation please.
>Today, no electronic engineer recommends diodes
>for contactor coil suppression. They are not the
>best, nor the second, nor the third, nor even fourth best way to do the
job.
"The job" is not a constant . . . The means
by which "the job" is accomplished is also not
a constant. Many papers have been written on
replay performance and system integration issues.
Some were done by very competent designers who
were marginal writers/teachers. For example: In
the paper at:
http://www.aeroelectric.com/Reference_Docs/Tyco/Tyco-Paper_on_Coil_Suppressi
on.pdf
The paper opens with a concern for damage to
normally open contacts that are switching high-
inrush currents and attributes this to selection
of coil suppression technique. In fact, the damage
being cited is mostly a matter of contact bounce
during a stressful portion of the operating cycle
where contacts close, open and re-close
perhaps a dozen times (at the worst possible moment)
when the switched currents are many times higher than the
steady state ratings of the contacts.
Further, coil suppression has nothing to do with
contactor performance on energizing the coil, only
upon the de-energizing event.
Keep in mind too that these guys write about
RELAYS rated to advertised service life in tens of
thousands if not hundreds of thousands of cycles.
We're discussing battery and starter contactors
that will probably fail due to corrosion before they
die from service life stresses.
Finally, I did real studies of changes to contact
spreading velocity at de-energization for the
two most aggressive devices in the airplane . . .
battery and starter contactors. I thought I might
have obvserved a 2 or 3% increase in arcing time
for diode versus NO coil suppression. How does this
drive a decision to put the hex on the lowly diode
coil suppressor?
>Mechanical relays and contactors depend upon
>magnetism generated by an electric current
>running through a wire coil. When the current
>stops, the magnetic field collapses. But the
>relay does not know the difference between a
>wire coil moving in a magnetic field (as in a
>generator) or a magnetic field moving in a wire
>coil (as in a collapsing magnetic field). Thus a
>large voltage=941000V to 1500V typically=94is
>induced in the coil. This current goes the same
>direction the original current did=94so it slows
>the contact opening=94allowing arcing, chatter,
>bouncing, contact welding and even
>re-closure! Perihelion Design sells 18V 600W
>Bi-Directional Zener Transient Voltage
>Suppressors P6KE18CA (for 14.5V systems) that
>provide the most modern technical solution to relay coil suppression.
>
>See my website or buy your own. The Gigavac GX11
>contactor already has bidirectional zeners for
>coil suppression. Gee, I wonder why!?\
I can suggest a good reason why: Simple diodes are
polarity sensitive . . . I.e. if you build the diode
into the contactor, options for coil connection are
bounded by polarity of the diode. In starter
contactors where diodes are commonly built in, the
base of the contactor is always (-) so the built in
diode offers low risk for miswiring. Bi-directional
Transorbs are goof-proof.
The bi-directional zener offers a form of coil energy
suppression that is not polarity sensitive and dissipates
stored inductive energy in a combination of coil resistance
and I*E product of the zener. Further current tending
to keep the contactor closed after deenergizing has
a lower on-set value . . . hence the faster drop-out
response.
>This issue has been argued here for years, so ignore me Bob.
So why bring it up again? I've measured, demonstrated and
explained the value/function of the various coil transient
suppression methods on the devices we're talking about . . .
CONTACTORS.
http://tinyurl.com/mcgg87
On your website at:
http://www.periheliondesign.com/suppressors.htm
you say . . .
"Thus a large voltage=AD1000V to 1500V typically=ADis induced
in the coil. This current goes the same direction the original
current did=ADso it slows the contact opening=ADallowing arcing,
chatter, bouncing, contact welding and even re-closure!"
The first statement is correct, the voltage is high . . . but
fails to say where it goes or what devices are placed at risk.
A diode delays contact opening after the coil power is removed. But
differences in contact spreading velocity are so small (if they
exist at all) as to be difficult to measure. I challenge you to
go to the workbench and show me a setup that produces bounce,
chatter, increased arcing, tendencies to weld N.O. contacts
upon de-energization, and/or evidence of re-closure as a
consequence of simple diode coil suppression.
If not demonstrable, how about a hypothesis as to how
contacts that are moving away from each other are subject
to a force that accelerates the contact mass in the opposite
direction and effects re-closure? May I suggest this notion is
absurd the the extreme?
Your hypothesized 60v transient generated by simply turning
off a large load is also in error. This event happens during
the automotive definition of load dump that includes a
BATTERY DISCONNECT. Alternators that go through MPA's
rebuild facilities are tested for it's effect on the
alternator . . . believe me it can be a whole lot worse
than 60V. But this is rare in airplanes. What's the likelihood
that dropping a max rated load is exactly coincident with
opening the battery contactor? In your functional description
at:
http://www.periheliondesign.com/suppressors/Whackjack%20Manual.pdf
There's no mention of battery disconnect . . . hence the
60v number is hyperbolic persuasion. Your citation of
FAR 25.581 is equally hyperbolic. If you're going to evoke
lightning qualification issues to an RV, then believe me,
the task is about 100x more complex than adding a "WhackJack"
to the system.
I've managed numerous investigations into relay and switch
contact failures in 40+ years of hammering on airplanes.
It was not uncommon to discover things about some products
than the "engineers" and "manufacturer's reps" assigned to
support those products did not know. Quite often,
those individuals were tasked with supporting a legacy
product they didn't design and never integrated into
a system.
There's an archive of Tyco publications on the subject
at:
http://www.aeroelectric.com/Reference_Docs/Tyco/
These are largely factual and the ideas presented are useful
to consider where applicable . . . but they don't apply
to what we've been talking about.
If you choose to play in this sandbox, bring the right
shovel, bucket and support them with a willingness to explain
and teach. I'm sure that your products perform as they
are intended to by their designers. But their prophylactic
application to ward off the gremlins described on your
website is not consistent with what we have known about electrical
systems (and their component parts) in airplane for over 100 years.
Bob . . .
Message 6
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| Subject: | Spike catcher diode |
>I haven't decided if I'm going to use zeeners, diodes or just
>replace the solenoid on some scheduled basis. I've yet to see
>anything from anyone which shows how much longer (days, weeks or
>years) a solenoid lasts by adding these gadgets.
The inclusion of coil suppression is for the benefit of the
controlling device (switch or push-button). From the time
that batteries and starters went into light airplanes (1945?)
until the rectifier diodes came to Cessna's attention (1963?)
there was no coil suppression on battery or starter contactors.
We had a devil of a time converting a leaded electronic component
into an airplane part. We COULD have attached the diodes like
this . . .
http://www.aeroelectric.com/Pictures/Contactors/s701-1.jpg
But somebody decided to mount the diodes on little strips
of phenolic sheet with eyelets at the ends to accept
screws and wires with terminals crimped on them. Added a
whole lot of labor and fragility to an otherwise inexpensive,
robust device. I note that the Cessna Service parts lists
still show a lot of "diode assemblies" for $15 to $50. So
I guess they're still sticking diodes on some form of
built-up assembly.
Even today, plain-vanilla diodes are used across contactors
in production aircraft.
> The problem is real, but actual life expectancy needs to be
> measured to satisfy my interest.
Excellent question. I don't recall that we were ever aware
of a service life "problem" with either contactors or their
controlling switches in the years before diodes. But I
recall Gordon Wood (our PhD physicist) putting a H-P peak-
reading voltmeter across a contactor coil, seeing a 500+ volt
reading and saying, "Hot damn . . . we need to do something
about that!" And we did.
Given that we were unaware of service life issues attributable
to LACK of DIODES, we were destined to be equally ignorant of
service life benefits after diodes were ADDED. But we sure took
care of that 500v spike! I don't think Gordo ever put a 'scope
on the system to see where the spike goes. I suspect he would
have seen this:
http://www.aeroelectric.com/articles/Spike_Catching/CH_Opening_No_Suppression.gif
Noise conducted to the bus is very low energy, low amplitude
compared to what the controlling switch sees.
If you are the typical pilot which flies 35 hours / year it will
fail from sitting around before it fails from arching.
Exactly! There's a ton of papers written to the task of
wringing the last few hours of service life from various products
rated in gazillions of cycles.
But if there was ever a low duty-cycle application for any
electro-whizzy, it's the personally owned light airplane,
snow-mobile, or bass boat.
Your perception of effects of age and environment being
more profound than effects of service life is quite
accurate!
Bob . . .
Message 7
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| Subject: | Re: Grounding question |
At 11:17 AM 7/8/2009, you wrote:
>
>Hi Bob and all,
>
>A buddy asked for help in adapting the wiring of his factory built
>Rotax 912 S aircraft.
>He wishes something more similar to fig Z16
>
>His battery, contactor, regulator and capacitor are under the seats,
>whereas the ground bus is on the firewall.
>The factory originally grounded the regulator and battery contactor
>direct at the minus post of the battery.
>Is it advisable to retain this configuration, or would it be better
>to ground those at the ground bus on the firewall, and retain only
>one fat ground wire running from the fwl to the minus pole of the battery.
>
>Thanks in advance for your help,
You will note that none of the Z-figures attaches
more than single, fat-wire to a battery terminal. I know
some manufacturers of electro-whizzies are fond
of asking builders to "hook my product right to the
battery terminals".
In the world of TC aircraft, we're sensitive to the
effects of wrench-monkies who routinely replace certain
articles over the lifetime of the airplane. Batteries
certainly get replaced about as often as tires. It's
not considered good practice to inject more variability
than necessary into the reliable opening/closing of
a fastener. Hence, batteries never get more than one
wire on their terminals. In some cases, we even eliminated
human-induced variability by designing batteries with
connectors on them!
Emacs!
The short answer is, I recommend you stay with the architecture
described in Z-16.
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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| Subject: | Contactor question |
I'm currently planning a VP-200 Config 4 implementation in my RV-10 (similar
in concept to Z-14).
I'm at the stage where I need to install any required conduit, so I started
some high level physical power wire planning.
If I keep the battery and x-tie contactors in the rear with the batteries,
it appears that I have to run 13 wires from the firewall back to the
batteries, whereas if I locate the battery and x-tie contactors up front,
only 5 wires will need to be run to the batteries.
This appears to be a no-brainer decision to minimize the amount of wire to
be installed. Are there any issues with not having these contactors
co-located with the batteries (assuming appropriate wire gauges are used)?
I would be interested in talking with any RV-10 builders that are
considering a Config 4 implementation, as well as those that initially
thought about a Config 4 then switched to another config.
thanks,
bob
Message 9
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| Subject: | Using Mono Headset in Sterio Jack |
Hi Bob
Are there any issues to be concerned about if I was to use a mono
headset in jacks that are wired for stereo?
Thanks
John
Message 10
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| Subject: | Re: Using Mono Headset in Sterio Jack |
John wrote:
> Hi Bob
>
> Are there any issues to be concerned about if I was to use a mono
> headset in jacks that are wired for stereo?
>
> Thanks
>
> John
>
If you plug a mono plug in a stereo jack, the 2nd channel will be tied
to the ground 'sleeve' of the plug. It probably won't hurt the intercom
(it probably has series resistors in its outputs to protect against just
this issue) but it sure ain't gonna help.
There are several possible 'workarounds'. The simplest (which will lose
the right channel from the intercom) is to wire a stereo plug (tip &
sleeve only) to a mono inline jack. Leave the ring terminal of the
stereo plug unconnected. Use this adapter between the headset plug &
your intercom jack.
Charlie
Message 11
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7/10/2009
Below copied for your info from the BMA web site.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
===============================================
"Well, it's been fun. We developed a whole new class of machine, started an
industry, dominated it, and are now leaving it. BMA will be ceasing
production and spinning down. The best way to contact us is via email:
support@bluemountainavionics.com. Please don't call, since the office is
not staffed on a scheduled basis. We'll still be around to service, support
and assist as time permits, homebuilders helping other homebuilders, but BMA
is essentially closed. This website is paid up and will be around for a few
years at least, and there is some hope (and a fond desire) that we may
return to full production when the economy recovers. Database updates are
still be available on this site, and service, maintenance and repairs are
still available for all BMA products. We are actively seeking someone to
buy the code and continue development. If your interested, please email."
Message 12
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| Subject: | Re: Contactor question |
At 04:01 PM 7/10/2009, you wrote:
>I'm currently planning a VP-200 Config 4 implementation in my RV-10
>(similar in concept to Z-14).
>
>I'm at the stage where I need to install any required conduit, so I
>started some high level physical power wire planning.
>
>If I keep the battery and x-tie contactors in the rear with the
>batteries, it appears that I have to run 13 wires from the firewall
>back to the batteries, whereas if I locate the battery and x-tie
>contactors up front, only 5 wires will need to be run to the batteries.
For Z-14 with rear mounted batteries consider
mounting the contactors aft and the crossfeed
contactor on the forward side of the firewall.
This provides a good power distribution location
for fat wires forward of the firewall.
If batteries are aft, then you have two fat wires
coming forward. Batteries are grounded locally.
http://aeroelectric.com/Pictures/Batteries/Battery_Install_OBrien_1.jpg
http://aeroelectric.com/Pictures/Batteries/Battery_Install_OBrien_2.jpg
http://aeroelectric.com/Pictures/Batteries/Battery_Install_OBrien_3.jpg
This leaves two contactor wires plus what ever
wires come forward off the battery busses.
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: | Re: Using Mono Headset in Sterio Jack |
<< Are there any issues to be concerned about if I was to use a mono
headset in jacks that are wired for stereo? .. John >>
<< There are several possible 'workarounds'. The simplest (which will lose
the right channel from the intercom) is to wire a stereo plug (tip & sleeve
only) to a mono inline jack. .. Charlie >>
There is an even simpler, but not foolproof, workaround. Insert the mono
plug only to the first detent, not all the way in. It will stick out about
3/16 inch. This connects both sides of the mono headset to one stereo
channel. Be careful to not accidentally push the plug in all the way.
Tom Kuffel
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