Today's Message Index:
----------------------
1. 04:51 AM - Re: AeroElectric-List Digest: 7 Msgs - 04/12/07 (Mike Doyle)
2. 06:24 AM - Re: DIY Intercom System (Robert L. Nuckolls, III)
3. 06:54 AM - Re: 12V batteries in series - a few more followup questions (Robert L. Nuckolls, III)
4. 07:09 AM - Z-16 (Gaye and Vaughn)
5. 07:34 AM - Re: Z-16 (Gilles Thesee)
6. 08:20 AM - Re: Z-16 (Robert L. Nuckolls, III)
7. 08:23 AM - Re: Re: DIY Intercom System (Ken)
8. 09:44 AM - Re: Re: DIY Intercom System (Ernest Christley)
9. 10:04 AM - Z-11 (Gaye and Vaughn)
10. 11:45 AM - Re: Z-11 (Matt Prather)
11. 03:32 PM - Re: Z-11 (Robert L. Nuckolls, III)
12. 03:37 PM - Re: Z-11 (Robert L. Nuckolls, III)
13. 04:43 PM - Mag Grounds (Jim Piavis)
14. 11:37 PM - Relay and capacitor info needed ()
Message 1
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Subject: | Re: AeroElectric-List Digest: 7 Msgs - 04/12/07 |
I built one of these intercom kits at least 12 years ago, and have been
using it since then. Works great.
http://www.rst-engr.com/rst/catalog/intercom.html
Mike Doyle
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Subject: | Re: DIY Intercom System |
At 09:30 AM 4/12/2007 -0700, you wrote:
>
>Hello Listmembers,
>
>I would like to introduce myself. I'm a brand new builder of a Zenith
>Zodiac XL kit. I plan to do a lot of electronics mods myself (flunked
>polytechnic college in a previous life many moons ago).
>
>I have Bob's book and I think it's great. has anybody on the list ever
>attempted to build a two place intercom? I think the intercoms on the
>market are way overpriced. I found schematics for a David Clark intercom
>on their website and think about using that for inspiration.
The audio portion of an intercom is stone simple. The
tricky part is development of a background noise reduction
system that's effective, drift free and relatively immune
to variables in ambient noise.
Designs of yore used a simple rectifier of total signal
and a comparator to decide when signal levels were high
enough (because someone's voice was added to background
noise) to open the signal gate and allow everything (voice +
noise) to be heard in everyone's headphones.
There's a wealth of signal+noise to noise deduction philosophies
with the more modern techniques using rudimentary digital
signal processing software in a microcontroller to do
the threshold adjustments and make gating decisions in
real time. These intercoms don't have or need "squelch"
adjustment knobs.
The systems that do have manual adjustments can benefit
from a variety of active filter techniques that improves
the squelch system's ability to sort speech signals from
noise signals. What you pay for in an commercial-off-the-shelf
(COTS) intercom system is a whippy noise gating system and usually
with a warranty. If you don't like it, you can generally
get you money back with a minimum investment of $time$.
It's not my intent to discourage you from attempting
a satisfactory design on your own but be advised that
when all the solder joints have cooled and you have
a successful system running in your airplane, you will
have invested much more $time$ on the project than you would
have expended on a COTS product.
I've got some ideas for a software based noise gating
system I'd like to try and I've discussed it with my
software guru but this project is WAY back on the
burners. The development effort is significant and
the competition in this arena is competent and
in my never humble opinion, nicely priced. I'm doubtful
that it's worth my $time$ to step into that bull-fight.
Bob . . .
----------------------------------------
( IF one aspires to be "world class", )
( what ever you do must be exercised )
( EVERY day . . . )
( R. L. Nuckolls III )
----------------------------------------
Message 3
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Subject: | 12V batteries in series - a few more followup |
questions
>I might have missed it (I re-checked), but I never saw an answer/reply to
>the questions below. As always, I appreciate any thoughts you offer. I'm
>indebted to your efforts/experience.
>Rick
You done good. I sift through the e-mails and respond
from the bottom up. If I didn't, I'd be making replies
to stuff posted back in 2006.
So if someone's query doesn't make the cut for time and
inspiration several days in a row, it's not likely to
bubble to the top automatically and needs to be reposted.
>BobN,
>Thanks much (as usual)!!! I'm going to try the omega bend connector, it
>should be pretty simple with the thin material - probably better than the
>straight/flat connector, perhaps not as robust as the 4AWG cable - sort of a
>compromise in my mind.
Agreed.
>Follow-up question#1: Let's say sometime in the future, one of the battery
>terminals or the omega connector strap comes loose or breaks off in flight.
>How would I know (during the flight)? My ignorant guesses below.
>
>a) The ammeter (shunt on the battery lead) would move from perhaps a slight
>charging state to zero, but that might not be noticeable.
>
>b) I understand the alternator would not be happy without the battery. But,
>how would I know? Voltage fluctuations? Potential overvoltage (crowbar)
>scenario?
>
>c) Other???
I don't recommend battery ammeters and for the most part,
you wouldn't notice anything. Many a Bonanza pilot has landed
and during shutdown discovered that he mis-flipped a switch
somewhere along the way and the battery has been off line
for some time.
The risk for running sans battery with alternators is that
a high inrush current system (landing lights, hydraulic gear motors,
etc) will "stall" the alternator if the battery is not on line
to fill in for milliseconds of inrush time. For the most
part, voltage regulation sans battery is not seriously
affected except for highly dynamic situations and these
situations do not offer hazardous situations.
One of the studies I want to conduct after the drive stand
is running . . .
http://www.aeroelectric.com/Pictures/Alternator_Test_Stand/DSCN0961.JPG
http://www.aeroelectric.com/Pictures/Alternator_Test_Stand/DSCN0962.JPG
http://www.aeroelectric.com/Pictures/Alternator_Test_Stand/DSCN0963.JPG
. . . is to explore and quantify system operating conditions
sans battery along with an investigation of how well modern
alternators will self-excite. It's been a long standing assumption
based on 1960's alternator technologies that one should always
have a source of alternator excitation energy aboard to insure
availability of engine driven power. For the most part, the
battery fills this role but some worriers have gone to the
effort of providing little kick-starting systems that run
whether or not a battery is present. We stirred that stew
on the C-337 in the mid 60's.
Alternators on Bonanzas will self excite and run sans
battery. It's not real clear that we don't have a similar
situation with belt driven automotives which cruise at over
10,000 rpm on the front of a Lyc.
Another new idea coming over the hill calls for inclusion
of a super-capacitor (1 farad or more) across the main
bus. This device may have much better noise filtering
characteristics than any battery. We'll see . . .
>Follow-up question #2: What type of nut should I use on the threaded
>battery terminals? I'm assuming just a plain (AN345) nut (Cad plated,
>Stainless, other)? However, it would be nice to safety it somehow (perhaps
>overkill). Would it make sense to use two nuts (a jam nut)? Would it make
>sense to use a nylon lock nut as the 2nd jam nut? Would it make most sense
>to just use one all metal stop nut (AN363)
The thing that's going to put these joints at risk
for loosening is vibration of a mass that imparts
ROTATIONAL forces. The light and flexible welding
cable leads and your thin brass omega jumper do not
present great risks. Any of the schemes you've described
are probably overkill. Go the easiest route if at all.
>Follow-up question #3: Assuming a ground stud through the firewall, what
>should the stud be made of (steel) (zink plated) ((brass) (other)? What
>type of nut(s) should I use on it (same as the battery terminals)? What
>type of nut should I use on the engine side of the engine ground braid?
Please use brass hardware for this. 5/16" minimum and 3/8" preferred.
Ordinary brass nuts torqued to recommended values. After your
40 hour fly-off, consider disassembling the array of ground stud,
nuts and terminals. Do final cleaning. Re-assemble with Locktite
271 or similar on threads and torque to recommended values.
It's unlikely that this joint needs to be opened over the lifetime
of the airplane. Making it semi-permanent after you've completed
the development phase of construction is not an unreasonable thing
to consider.
Bob . . .
Message 4
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Good Morning Bob,
I have pasted my question to Lockwood and their answer. Unfortunately, I
can't seem to figure out if your drawing complies with the issues
delineated in their answer, even after attending your seminar. Please
excuse my confusion, but the sparks don't seem to be propagating
properly in my central processor.
Vaughn Teegarden
Europa XS, Rotax 914
THEIR ANSWER
This is an AC generator system, the regulator is separate.
The C is indeed a control circuit and must power the regulator at all
times when the engine is running. When the engine is shut off it too (C
terminal) must disconnect, or the battery will drain. The C lead must
be in contact at all times while running or the regulator would fail
internally.
----- Original Message -----
From: Gaye & Vaughn
To: info@lockwood-aviation.com
Sent: Wednesday, April 11, 2007 10:07 AM
Subject: Wiring of Ducati regulator
I am attaching the wiring diagram proposed by Bob Nukolls for the
Rotax engines. You will notice that he uses the "C" lead to control the
internal alternator. Does this risk burning up of the regulator or
damaging the alternator? A lot of builders are using this method of
wiring their aircraft. I would like to know from Rotax itself why this a
bad practice and I think that it would benefit Rotax to contact Bob at
AeroElectric and explain it to him so that he will quit suggesting his
wiring solution.
Thanks,
Vaughn Teegarden...purchasing within 3 months
Message 5
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Gaye and Vaughn a crit :
> Good Morning Bob,
>
> I have pasted my question to Lockwood and their answer. Unfortunately,
> I can't seem to figure out if your drawing complies with the
> issues delineated in their answer, even after attending your seminar.
>
Vaughn,
When wiring our 914 project, I made some study on the Rotax regulator.
After much research and bench testing, it appeared that wiring the C
wire to the the B terminal or the positive terminal of the capacitor
would ensure correct working of the system. So you don't sever the
connection of the control wire to a voltage reference.
But IF the regulator fails to regulate (a not so unlikely event, judging
from my buddies homebuilders mishaps), the capacitor will take the full
unregulated voltage of the alternator (up to 100V), and may well burst.
The latest version of Z16 seems to ensure a safe working : in case of OV
event, the alternator is isolated from the ships circuit. There is
nothing wrong with spinning the alternator on its own. I did it many
times on the bench.
On reconnecting, the regulator sees the battery reference voltage, and
starts regulating right away.
I must confess that after testing the Rotax regulator, I switched for a
Schicke GR4 regulator, with better regulation and thermal rejection.
Worked great for 120 flight hours.
I'm presently working on a Rotax 912S porject , and followed the latest Z16.
First flight expected within two months.
Best regards,
Gilles
http://contrails.free.fr
Message 6
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At 10:09 AM 4/13/2007 -0400, you wrote:
>Good Morning Bob,
>
>I have pasted my question to Lockwood and their answer. Unfortunately, I
>can't seem to figure out if your drawing complies with the issues
>delineated in their answer, even after attending your seminar. Please
>excuse my confusion, but the sparks don't seem to be propagating properly
>in my central processor.
>
>Vaughn Teegarden
>Europa XS, Rotax 914
>
>
>THEIR ANSWER
>This is an AC generator system, the regulator is separate.<?xml:namespace
>prefix = o ns = "urn:schemas-microsoft-com:office:office" />
>
>The C is indeed a control circuit and must power the regulator at all
>times when the engine is running. When the engine is shut off it too (C
>terminal) must disconnect, or the battery will drain. The C lead must be
>in contact at all times while running or the regulator would fail internally.
An analysis of the schematic for the Ducati regulator
supplied with Rotax engines . . .
http://www.aeroelectric.com/Pictures/Regulators/regul_912.jpg
. . . confirms that the C terminal supplies operating power
for the low level electronics along with a path for bus votlage
sensing. Opening this lead while the engine running simply shuts
the regulator down assuming that input voltages from the
dynamo do not soar to deleterious levels . . . doubtful but
I have no way to prove it.
Further, their admonition about disconnecting "C" when
powered down to avoid battery drain is valid for systems
that do not have battery contactors or switches (like
ultralights I suppose).
Their response is typical of many suppliers who are exceedingly
limited in their understanding of the product they sell and
variabilities in how their customers might properly use
those products. In a nutshell . . . wire per Figure Z-16
of . . .
http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf
. . . and do not concern yourself with any disagreement
you may perceive between the little information they have
to offer and well considered advice you might receive
elsewhere. It's unlikely that anyone on staff at your
supplier can discuss applications and options with
any logic. They're only parroting information fed to them
by others who are equally un-informed as to how you meet
your design goals.
Bob . . .
----------------------------------------
( IF one aspires to be "world class", )
( what ever you do must be exercised )
( EVERY day . . . )
( R. L. Nuckolls III )
----------------------------------------
Message 7
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Subject: | Re: DIY Intercom System |
Sorry I can't find your name but for the original person asking, while
any homemade intercom is likely better than no intercom you might also
be content with the intercom that is included as part of some VHF
radios such as the Iccom A200 although I don't think that particular one
has Voice activation.
Bob I agree that it is probably not good use of time for most folks to
try and improve on something like the Flighttech hot mic intercom that
has no background noise that I can notice, whether someone is talking or
not. I think it uses a chip developed for telephone use rather than
custom DSP technology but it works amazingly well for me and the price
is right.
I guess I've only used the cheaper VOX intercoms but even with matched
headsets and perfectly adjusted squelch, they seem to pick up a lot of
background noise when someone is talking. Maybe the high end units are
better but I'd never go back to a VOX unit.
Ken
Robert L. Nuckolls, III wrote:
> <nuckollsr@cox.net>
>
> At 09:30 AM 4/12/2007 -0700, you wrote:
>
>>
>> Hello Listmembers,
>>
>> I would like to introduce myself. I'm a brand new builder of a Zenith
>> Zodiac XL kit. I plan to do a lot of electronics mods myself (flunked
>> polytechnic college in a previous life many moons ago).
>>
>> I have Bob's book and I think it's great. has anybody on the list
>> ever attempted to build a two place intercom? I think the intercoms
>> on the market are way overpriced. I found schematics for a David
>> Clark intercom on their website and think about using that for
>> inspiration.
>
>
> The audio portion of an intercom is stone simple. The
> tricky part is development of a background noise reduction
> system that's effective, drift free and relatively immune
> to variables in ambient noise.
>
> Designs of yore used a simple rectifier of total signal
> and a comparator to decide when signal levels were high
> enough (because someone's voice was added to background
> noise) to open the signal gate and allow everything (voice +
> noise) to be heard in everyone's headphones.
>
> There's a wealth of signal+noise to noise deduction philosophies
> with the more modern techniques using rudimentary digital
> signal processing software in a microcontroller to do
> the threshold adjustments and make gating decisions in
> real time. These intercoms don't have or need "squelch"
> adjustment knobs.
>
> The systems that do have manual adjustments can benefit
> from a variety of active filter techniques that improves
> the squelch system's ability to sort speech signals from
> noise signals. What you pay for in an commercial-off-the-shelf
> (COTS) intercom system is a whippy noise gating system and usually
> with a warranty. If you don't like it, you can generally
> get you money back with a minimum investment of $time$.
>
> It's not my intent to discourage you from attempting
> a satisfactory design on your own but be advised that
> when all the solder joints have cooled and you have
> a successful system running in your airplane, you will
> have invested much more $time$ on the project than you would
> have expended on a COTS product.
>
> I've got some ideas for a software based noise gating
> system I'd like to try and I've discussed it with my
> software guru but this project is WAY back on the
> burners. The development effort is significant and
> the competition in this arena is competent and
> in my never humble opinion, nicely priced. I'm doubtful
> that it's worth my $time$ to step into that bull-fight.
>
> Bob . . .
Message 8
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Subject: | Re: DIY Intercom System |
Robert L. Nuckolls, III wrote:
>
> It's not my intent to discourage you from attempting
> a satisfactory design on your own but be advised that
> when all the solder joints have cooled and you have
> a successful system running in your airplane, you will
> have invested much more $time$ on the project than you would
> have expended on a COTS product.
Just as a single data point....
I built the RST panel mount kit. The parts all went together quickly
and easily with the connectors being the hardest part. I believe the
total cost was right at $130. I had about 20 hours total invested in
building it.
The pay back for me is being able to lay my hand on it and say, "EYE
built that," with my chest pushed out. Unless you're as egotistical as
I am, it may not pay you to go this route. OTOH, I'm actually saddened
that RST is no longer selling their DIY radio kits.
--
,|"|"|, Ernest Christley |
----===<{{(oQo)}}>===---- Dyke Delta Builder |
o| d |o http://ernest.isa-geek.org |
Message 9
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Dang!
I had not seen Rev 11 of the Z drawings. I will incorporate this into my
dual alternator schematic. The internal Rotax alternator will be used as
an auxillary, which means the electricity that it generates will be
absorbed by the 22mF capacitor unless the 40amp eternal regulator fails.
Am I right?
Vaughn Teegarden
Message 10
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Vaughn,
I don't think that's precisely right.. Whichever alternator has a
regulator with the highest setpoint voltage (it's unlikely the setpoints
will be exactly equal) will provide all of the system power up to 100% of
the current it's capable of at that voltage. The other alternator will
only deliver power to the system when the system voltage drops below that
alternator's setpoint voltage.
I gather the Rotax alternator is actually a permanent magnet dynamo..
Anytime the system voltage is above the regulator setpoint, the
regulator's connection between the dynamo output and the buss is opened
(gated off). The AC voltage seen on the output of the dynamo will rise to
some peak value and remain there (50V?). I don't think any capacitor is
involved.
Regards,
Matt-
> Dang!
>
> I had not seen Rev 11 of the Z drawings. I will incorporate this into my
> dual alternator schematic. The internal Rotax alternator will be used as
> an auxillary, which means the electricity that it generates will be
> absorbed by the 22mF capacitor unless the 40amp eternal regulator fails.
> Am I right?
>
> Vaughn Teegarden
Message 11
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At 01:04 PM 4/13/2007 -0400, you wrote:
>Dang!
>
>I had not seen Rev 11 of the Z drawings. I will incorporate this into my
>dual alternator schematic. The internal Rotax alternator will be used as
>an auxillary, which means the electricity that it generates will be
>absorbed by the 22mF capacitor unless the 40amp eternal regulator fails.
>Am I right?
>
>Vaughn Teegarden
Figure Z-11 is a single alternator system. If you want to combine
a robust belt driven alternator with a permanent magnet backup
(like the 18A machine on the Rotax) consider Z-13/8.
The latest revisions of all the Z-drawings is available from
the website at
http://aeroelectric.com/whatsnew.html
Bob . . .
----------------------------------------
( IF one aspires to be "world class", )
( what ever you do must be exercised )
( EVERY day . . . )
( R. L. Nuckolls III )
----------------------------------------
Message 12
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At 01:04 PM 4/13/2007 -0400, you wrote:
>Dang!
>
>I had not seen Rev 11 of the Z drawings. I will incorporate this into my
>dual alternator schematic. The internal Rotax alternator will be used as
>an auxillary, which means the electricity that it generates will be
>absorbed by the 22mF capacitor unless the 40amp eternal regulator fails.
>Am I right?
>
>Vaughn Teegarden
Ooops. I missed the earlier posting with power distribution
diagram. Ignore the earlier post on this thread.
Bob . . .
----------------------------------------
( IF one aspires to be "world class", )
( what ever you do must be exercised )
( EVERY day . . . )
( R. L. Nuckolls III )
----------------------------------------
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I'm sure this has been discussed but searching the archives didn't produce
a lot, so I wanted to request a clarification.
I'm wiring up two Slick mags with SPST switches. From the Z-13 diagram here
's how I understand the mag wiring:
1) Use 18AWG shielded wire
2) Connect the mag-side ground pigtail to the ground stud on the mag.
3) For switch side, connect the ground pigtail to the ground side of t
he switch, thus when the switch is closed, the mag grounds to the engine vi
a the mag, using the shielding for the ground path and negating a parallel
ground path.
Do I have this correct?
Thanks,
Jim
RV-7 Wiring
Message 14
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Subject: | Relay and capacitor info needed |
Have a few questions (4) about relays and capacitors to be used on my 914
Rotax powered Europa:
1) If I use a B+C S704-1 "Sealed" relay for OVP to open and close a yellow
output wire of the internal generator (mounted on engine side of
firewall), are the chances good it will not blow apart if I choose to wave
soar up to 35K with long wings? How about at 18K with intercooled motor
running hard and temp of relay gets up to 212F?
2) If I use a Bosh 75 amp "Vented" SPST relay #75251 from
www.waytekwire.com on the engine side of the firewall used in parallel
with the B+C for OVP to disconnect the 22K uF capacitor from my E-Bus.
Should the service life be reasonable on a vented relay on the engine side
of the firewall on an airplane stored for the most part in a unheated tin
hangar? It has a small slit to allow it to vent. (On my design, if
capacitor shorted it would draw down the E-Bus with no way to sever short
without 2nd relay. My design addresses failure of battery (opened or dead)
when attempting in flight restart after soaring)
3) When turning on and off the internal generator, the 75 amp Bosh relay
will be used to charge up the 22K uF capacitor. Can this relay most like
give good service charging up the capacitor at least once per flight?
Could the B+C S704-1 "Sealed" relay most like take the abuse of charging
up the capacitor at least once per flight and be used in place of the Bosh
75 amp? (Bosh weighs in at 3.1 oz and has dual contacts)
4) I want to use for pitch trim small "Sealed" Osram 12v 5a relays from
Digikey pn G6B 2214P US DC12, are the chances good it will not blow apart
if I choose to wave soar up to 35K with long wings? Will be mounted in
cockpit.
Thx.
Ron Parigoris
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