Today's Message Index:
----------------------
1. 06:09 AM - Re: Catch diode location (Eric M. Jones)
2. 07:19 AM - Re: Re: Catch diode location (Robert L. Nuckolls, III)
3. 07:31 AM - Re: Re: Strobe Noise Low Voltage? (Robert L. Nuckolls, III)
4. 07:41 AM - Re: Re: Trim Tab Indicator (Robert L. Nuckolls, III)
5. 08:14 AM - Re: Catch diode location (jonlaury)
6. 08:42 AM - Re: Catch diode location (Eric M. Jones)
7. 09:56 AM - Re: Re: Catch diode location (Robert L. Nuckolls, III)
8. 05:54 PM - Laptop supply for your car/airplane (Robert L. Nuckolls, III)
9. 06:24 PM - Re: Laptop supply for your car/airplane (Bill Boyd)
10. 07:52 PM - Re: Laptop supply for your car/airplane (Joe Dubner)
11. 08:25 PM - Re: Laptop supply for your car/airplane (Bill Boyd)
Message 1
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Subject: | Re: Catch diode location |
Modern relay and contactor manufacturers recommend using bidirectional Zeners for
coil suppression, NOT diodes.
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 voltage1000V to 1500V
typicallyis induced in the coil. This current goes the same direction the
original current didso it slows the contact openingallowing arcing, chatter, bouncing,
contact welding and even re-closure.
http://www.periheliondesign.com/suppressors/SnapJack.pdf
Or buy your own, I recommend P6KE18CA for general purposes. Another advantage is
you can't put them in the wrong direction. They are symmetrical.
--------
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=315939#315939
Message 2
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Subject: | Re: Catch diode location |
At 08:04 AM 10/16/2010, you wrote:
>
>Modern relay and contactor manufacturers recommend using
>bidirectional Zeners for coil suppression, NOT diodes.
. . . an assertion that appears to be based
upon a paper published by Tyco authors that
in-expertly speak to issues not relevant
to the manner in which we use diodes on
our relays and contactors. Furhter, they
made mis-interpreted the significance of
their own data.
This was examined at length some years
ago Eric and you offered no evidence
or analysis contrary to the explanations
I demonstrated and published. If you have
some personally developed rationale for
contradicting what I wrote, please bring
it forward.
Bob . . .
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Subject: | Re: Strobe Noise Low Voltage? |
At 02:07 PM 10/15/2010, you wrote:
><michaelherder@beckgroup.com>
>
>I'm not intentionally testing it that low, it's just that I'm not
>flying and I'm only running the engine every couple of weeks. I've
>spent hours upon hours trying to find my strobe noise issue. In the
>mean time, I'm realizing that I haven't charged the battery and all
>the while my strobes are draining battery.
>
>Last night it just occured to me that my problem might just be
>related to that. And, I dont care if there is strobe noise at 10V
>as long as that is the issue and not a poor ground or something similar.
This thread brings up several thoughts from
the depths of past experiences . . .
The noise levels you may be hearing while parked
in the hangar just may be too small to be significant
with the engine running . . . or with the aircraft
in flight.
I recall being summoned to the King Air line many
moons ago to help with some blower motor noise that
was reported audible in the cockpit intercom system.
When I got there, I discovered that the volume controls
were all maxed out and yes, you could hear some motor
noise that went away when the blower breaker was
pulled. After repositioning the controls to levels
typical of normal flight conditions, I asked if
they thought the noise might be objectionable or
even perceptible over normal cockpit noises.
They checked a few more airplanes and then talked
to some pilots and decided that it was a non-problem.
This scenario has repeated many times. No system is
totally free of extraneous noises. The benchmark
for usefulness is quantified by Signal to Noise Ratio.
Make sure your observations are not being made under
extraordinary measurement conditions.
It's also possible that a power supply becomes extra-
noisy under low voltage conditions. Suggest you
invest in a nice 13.8v, switchmode power supply
to power up systems on the ground. There's a boat
load of nice supplies on Ebay right now.
http://tinyurl.com/2fgxrrz
Bob . . .
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Subject: | Re: RE: Trim Tab Indicator |
At 03:21 PM 10/15/2010, you wrote:
Bob:
A couple of questions on your miniature meter movements;
How does one change the scale?
I lay out a new scale plate in AutoCAD.
For b/w plates, I print the new scale on
full-sheet Avery label material (sticky
back w/peel-off cover) and a laser printer.
For color I use matt photo paper and color
printer. New scales are attached to the back
side of the existing scale plate.
Is it difficult to get the face plate off?
I don't take off the old one, just put the
new one over the old one or on the back side
of the existing plate.
Would just a piece of paper with the scale you
want printed on it be sufficient for the scale or
would you have to use a special paper? I presume
the meter is a 0 to full scale operation. Is
there any easy way to make it a center zero
meter such that you could use it for a 30 0 30 ammeter?
It depends on the pointer's zero-springs.
SOMETIMES . . . the rear spring has enough
adjustment travel to allow moving the zero-
current pointer position to the center of
the movement's travel. I've not tried it
with these devices that I can recall.
Also, I was unable to find the product listing
for the price of the miniature meter on your webpage. How much is the meter?
The instruments I hypothesized in the posting
do not exist. I would have to do some 'real'
scale stickers and modify some new instruments.
I have a load-meter that is already in stock.
https://matronics.com/aeroelectric/Catalog/AEC/9007/9007.html
The instrument with a shunt is $70. To do a
one-of-a-kind would be a bit more.
Bob . . .
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Subject: | Re: Catch diode location |
Eric and Bob McC,
Thank you both for spelling it all out for me. I like the bi-di- zener solution
because it's idiot proof and perfect for people like me that have just enough
electronic knowledge to be dangerous.
Eric, your schematics of all the different scenarios are priceless. With all the
other sorts of subjective decisions involved in building my plane, it's REALLY
a luxury to have an experienced person say "Here, do it this way".
Contributions, like yours, to this forum, really make it sing.
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=315953#315953
Message 6
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Subject: | Re: Catch diode location |
The application of relay coil suppression with DC relays
www.ciitechnologies.com/appnotes/app_pdfs/13c3311.pdf
Coil Suppression Can Reduce Relay Life
relays.tycoelectronics.com/appnotes/app_pdfs/13c3264.pdf
Coil Suppression
www.leachintl2.com/english/english2/vol6/properties/how7.htm
Coil Suppression Techniques:
www.newark.com/pdfs/techarticles/crydom/May2010_SolidStatements.pdf
You want more?
Using diodes for coil suppression is Soooooooooooo 1900's Bob. Come on board to
the next century.
--------
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=315957#315957
Message 7
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Subject: | Re: Catch diode location |
At 10:39 AM 10/16/2010, you wrote:
>
>
>Using diodes for coil suppression is Soooooooooooo 1900's Bob. Come
>on board to the next century.
Eric. Those papers were crafted for exploring
the tradeoffs for relays designed to operate
under rated loads for tens to hundreds of
thousands of cycles. And yes, SOME of the
studies show a benefit for not clamping the
recoil spike at near zero volts with a diode and
instead allowing it to rise to some level determined
by a zener.
THIS forum of discussion is not about crafting
electrical systems for military or space-grade
vehicles. On average, the GA light aircraft
flies 50 hours a year. OBAM aircraft as a class
are probably higher. So let us say after 20
years, the airplane MIGHT have 3000 hours on
it. How many THOUSANDS of operations might
any given relay or contactor see on such a
vehicle? Certainly not hundreds of thousands
nor even tens of thousands. How many of our
relays are loaded such that they switch rated
loads for every cycle?
Adding super-suppression to a relay might
produce a 10-20% improvement in laboratory
life tests running at rated loads . . . probably
NO improvement for lightly loaded or dry-circuit
switching.
The point is my friend that there is no value
to be secured for NOT buying coil suppression
devices at Radio Shack as opposed to the
"ideal" device ordered in from remote sources
for more money and time.
You have taken a few facts and morphed them
into a level of significance that is simply
not applicable to the customers you and I
serve for the airplanes they are building.
The next century? Hammers have been around for
thousands of years . . . but that does not mean that
the task of driving a nail is not well served
by keeping a few hammers in my toolbox.
The point of my writing for this audience is
to tailor a suggestion for adequate performance
at the least cost and time . . . i.e. the
elegant solution. The solutions may or may not
comport with findings produced in a laboratory
that will never study what we do on the OBAM
GA aircraft.
Bob . . .
Message 8
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Subject: | Laptop supply for your car/airplane |
I just ran across this item on Ebay:
http://tinyurl.com/2cyx7c7
With an input from your 14v bus, it can be set up
to provide the typical 18-20 volts needed by many
laptops.
Bob . . .
Message 9
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Subject: | Re: Laptop supply for your car/airplane |
Sounds like it may be useful for powering portable HF gear (the common 10
watt rice boxes) from Li-poly or Li-metal cells that don't readily supply
12.6-13.8v ganged as batteries. 85% efficiency is not stellar, but might
still be better efficiency than a dropping regulator on a 16v pack...
-Bill Boyd
On Sat, Oct 16, 2010 at 8:51 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> I just ran across this item on Ebay:
>
> * http://tinyurl.com/2cyx7c7*
>
> With an input from your 14v bus, it can be set up
> to provide the typical 18-20 volts needed by many
> laptops.
>
>
> Bob . . .
>
> *
>
> *
>
>
Message 10
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Subject: | Re: Laptop supply for your car/airplane |
Sounds like it might even /be/ HF gear :-)
That single-sided PCB with minimal filtering (judging only by the
pictures -- see http://tinyurl.com/2943gjk) probably radiates switching
transient energy through VHF and beyond.
Of course if used with a laptop PC as per Bob's original suggestion,
this point may be mute because the laptop has it's own issues. But I'd
be leery about using it around receiving equipment in an aircraft (or
elsewhere).
My $.02 -- YMMV.
--
Joe
Independence, OR
http://www.mail2600.com/position
http://www.mail2600.com/cgi-bin/webcam.cgi
Bill Boyd wrote:
> Sounds like it may be useful for powering portable HF gear (the common 10
> watt rice boxes) from Li-poly or Li-metal cells that don't readily supply
> 12.6-13.8v ganged as batteries. 85% efficiency is not stellar, but might
> still be better efficiency than a dropping regulator on a 16v pack...
>
> -Bill Boyd
>
> On Sat, Oct 16, 2010 at 8:51 PM, Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com> wrote:
>
>> I just ran across this item on Ebay:
>>
>> * http://tinyurl.com/2cyx7c7*
>>
>> With an input from your 14v bus, it can be set up
>> to provide the typical 18-20 volts needed by many
>> laptops.
>>
>>
>> Bob . . .
>>
>> *
>>
>> *
>>
>>
>
Message 11
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Subject: | Re: Laptop supply for your car/airplane |
Looks to be in a metal enclosure, though.
On Sat, Oct 16, 2010 at 10:49 PM, Joe Dubner <jdubner@yahoo.com> wrote:
>
> Sounds like it might even /be/ HF gear :-)
>
> That single-sided PCB with minimal filtering (judging only by the pictures
> -- see http://tinyurl.com/2943gjk) probably radiates switching transient
> energy through VHF and beyond.
>
> Of course if used with a laptop PC as per Bob's original suggestion, this
> point may be mute because the laptop has it's own issues. But I'd be leery
> about using it around receiving equipment in an aircraft (or elsewhere).
>
> My $.02 -- YMMV.
>
> --
> Joe
> Independence, OR
> http://www.mail2600.com/position
> http://www.mail2600.com/cgi-bin/webcam.cgi
>
>
> Bill Boyd wrote:
>
>> Sounds like it may be useful for powering portable HF gear (the common 10
>> watt rice boxes) from Li-poly or Li-metal cells that don't readily supply
>> 12.6-13.8v ganged as batteries. 85% efficiency is not stellar, but might
>> still be better efficiency than a dropping regulator on a 16v pack...
>>
>> -Bill Boyd
>>
>> On Sat, Oct 16, 2010 at 8:51 PM, Robert L. Nuckolls, III <
>> nuckolls.bob@aeroelectric.com> wrote:
>>
>> I just ran across this item on Ebay:
>>>
>>> * http://tinyurl.com/2cyx7c7*
>>>
>>> With an input from your 14v bus, it can be set up
>>> to provide the typical 18-20 volts needed by many
>>> laptops.
>>>
>>>
>>> Bob . . .
>>>
>>> *
>>>
>>> *
>>>
>>>
>>>
>>
>
>
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