magnetic field

[Jerry G.]

As long as the motor can be properly cooled in a vacuum, there is no
reason that it should have a problem. I would guess that a large type of
heatsink would be the way to go. Normally the air surrounding the motor,
and also having some air turbulence generated by the armature all
contribute to cooling it down in some way.

The other problem is that if lubricants are required, in a high vacuum
many of them would boil down and become thickened, unless they are of a
special type for operation in a vacuum environment. Thickened lubricant
would cause greater resistance for movement.

I know that the motors used in the aerospace industry are extremely
expensive. But, these are made to also be very reliable under very
stressful conditions.

--

Jerry G.
======

"Scorsi" <scorsi@earthlink.net> wrote in message
news:ea7e8dbc.0410111252.5d648332@posting.google.com...
I got into a debate recently regarding motors and the need for air
cooling,
can somebody confirm wether or not a normal motor can run in a vacuum
without overheating and if overheating is a problem, if there is any
type of motor that can run in a vacuum?

thanks Steve

 

[Ken Smith]

In article <NuZad.1429$y04.1329@newsfe5-win.ntli.net>,
Kryten <kryten_droid_obfusticator@ntlworld.com> wrote:
[...]

IIRC no cells like being drained as flat

IIRC the Silver Chloride (or something like that) battery loved being
discharged. You had to discharge it for storage. You could charge it up,
use it for a day and then run it flat. Discharged it would last for
years.

The down sides were: Charged it went bad in a month and they cost a *LOT*
to replace. The only Silver Chloride batteries still in use that I know
of are the ones for testing blasting caps.

--
--
kensmith@rahul.net forging knowledge

 

[Kryten]

"Dr. Slick" <radio913@aol.com> wrote in message
news:1d15af91.0410130040.591db8bc@posting.google.com...

NiCD cells DO like to be drained completely flat.

Otherwise you get the old memory effect

I must charge up my brain before discharging my mouth.

Battery University had some interesting text about memory effects.

If your NiCd battery likes an occasional deep discharge (don't we all?) then
perhaps your controller ought to apply one.
In normal operation it would trickle charge in the day ready for night duty,
but occasionally it might leave the lights on until sunrise. At which point
it starts a full charge again.

IIRC, lead cells do not mind being kept topped up all the time, as they can
become 'sulphated' if left discharged for a long time. They don't mind a
deep discharge either.

NiCd cells are rated to about 500 or 1000 cycles, hence the garden lamp
yearly cell replacement.

Lead cells can last for ages, as you can see from the many old jalopies
driving around.

I'm sure the British Antarctic Survey did the comparisons for their
monitoring stations, and chose lead acid cells as being the least
maintenance and longest lasting. They are simple and adequate.

Other cells strive for higher energy to mass ratios, but you pay for that in
fussier management. Lithium-ion cells have very high energy density, and
very fussy management. A tenth of a volt overcharge can ruin them. I have
some ordinary rechargeable lithium cells that I bought to replace
non-rechargeable ones in a LED torch. I accidentally discharged them fully
(pulling the LED off an LM3909 flasher does not reduce current to zero). To
see if this was okay, I checked the data sheets and found that although they
last for many shallow discharge cycles, they are only rated to about ten (!)
full discharges.

So rough rule of thumb is that the more recent the cell technology, the more
care they need to be managed.

I'm guessing you don't need the mass savings, higher price, or extra
management requirements.

Besides, I can go into my local electronics store (Maplins), buy a cheap 12V
lead-acid gel cell, and a solar panel specifically for keeping car
batteries topped up, and a PIR motion detector. That's half the job done.
The PIR thing runs off a 9V battery, so maybe buy an LM7809 regulator too.
Get the PIR to trigger a 555, which then drives a power tranny or relay to
switch on the lights. Oh and use an ORP12 photocell so it can tell night
from day.

Was the A of E text I emailed you any help?

K.

 

[Ken Taylor]

"Angga" <angga_rf@yahoo.com> wrote in message
news:a94b1df2.0410130631.635a30e8@posting.google.com...

I currently have a Liebert PSA700-230 UPS System, and for some reason
I do need to change its output frequency.

1. Are there any possibilities to change the cycle frequency of my UPS
from 60Hz to 50Hz? I'm in Australia and the mains' frequency is 50Hz.

2. The UPS utilize a microcontroller from MicroChip, PIC16C72A-20. Is
it possible to re-program the PIC? I cannot do the programming bit,
but will certainly be able to just flash it, anyway.

Thank you in advance, folks!
Angga RF

Check out their web-site:
http://www.liebert.com/dynamic/displayproduct.asp?ID=1082&cycles=60hz
according to the specs for other models int hat range they are 50/60Hz
auto-sensing. However I doubt that you can make them do 60Hz out for 50Hz
in, that would cause a problem or three if it goes into bypass mode. Is
reprogramming the PIC part of this idea? Frankly, it sounds sorta dangerous,
but have a chat with the local folk at:
Block P, Regents Park Estate 391 Park Rd.
Regents Park
New South Wales, Australia 2143

Phone: 612 9743 8555, 1300 367 686
Fax: 612 9743 8737

Their local folk here in NZ are more than helpful, I can't imagine they're
any different there.

Cheers.

Ken

 

[rein wiehler]

Franks wrote:

Hi, Friends
I want to buy a power supply. It should have a 110 VAC input and
110VDC or 220VDC output. Its capacity should be 100-200 watts. I live
in Toronto. Could you tell me where I can buy this kind power supply?
New or used one is fine.
thanks
try "House of 220" on Gerard st east near Coxwell. May they have

it with DC output.


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

 

[Boris Mohar]

On Mon, 11 Oct 2004 05:10:02 -0700, "Watson A.Name - \"Watt Sun, the Dark
Remover\"" <NOSPAM@dslextreme.com> wrote:

1 fA = 10^-15 _not_ 10^-16!


He said LESS than 1fA. 10^-16 is 100 attoamperes

It is doable with discrete front end of I/V op amp configuration. I
used
3N155

What's eye-opening is that at these ultra low currents, just a few
picofarads hold so much charge that it greatly affects the whole
measurement.

--
Boris Mohar

Yes. You have to have a patience of a sphinks when working with these. I
dropped one and it took full afternoon to recover. No Teflon either. One
thing worse are gravimeters which drift just they because the feel like it.

--

Boris Mohar

 

[R. Steve Walz]

Soundweapon wrote:

Classified US Government Technology

The United States government now has surveillance technology than can
electronically see and hear through walls.
-----------------

Maybe, but you're no threat, you're merely insane and they don't give
a fuck about you.

Get medical help for your schizophrenia. Why you have such a grandiose
delusion as to believe you're a threat is actually just part of your
illness.

-Steve
--
-Steve Walz rstevew@armory.com ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!! With Schematics Galore!!
http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public

 

[Nicholas O. Lindan]

"adrian" <adrian@bonni.freeserve.co.uk> wrote

pic chip to read a keyboard ... Which is best pic chip for such
a small project.

You don't say what sort of keyboard. If it is a std. 101 key
PC style you will need a PIC with lots of I/O. The minimum is
2 * sqrt (# keys) or 21 I/O lines for 101 keys (20 for 100 keys).
Mux and demux chips can lower the number of required I/O lines to
8.

If you want n-key rollover you will also need a large chunk (for a
PIC) of RAM - as usual you can trade off RAM requirements for program
size and complexity.

There are lots of truly awful keyboard scan and debounce algorithms
in the public domain, take your pick.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

 

[Clarence]

"Olive" <olivierdominguez@free.fr> wrote in message
news:f1b21c8c.0410151035.615637a7@posting.google.com...

I'm French electronic student, I need some informations about airborne
communications and data management solutions to airlines.
I need also technicals documentations aviation electronics systems,
electromagnetic compatibility, transmissions capacities.
Please send me your contacts or some internet links, technical Books,
etc....
Thank you.

I don't think you need our help.
Your supposed to do your own homework.

 

[Nicholas O. Lindan]

"TheDragon" <plandregan@gmail.com> wrote

"Nicholas O. Lindan" <see@sig.com> wrote in message
"adrian" <adrian@bonni.freeserve.co.uk> wrote

pic chip to read a keyboard ... Which is best pic chip for such
a small project.

You don't say what sort of keyboard. If it is a std. 101 key
PC style you will need a PIC with lots of I/O.

aren't PC keyboards already serial out? PS2 connector has + _ Data+ Data -
tahts it.

Ah, yes. It does depend _where_ you want to read the keyboard: is it
the IC inside the keyboard, or the chip that receives scan codes from
a commercial keyboard assembly.

If you want a table of scan codes, and I think timing, it used to be in
the IBM XT (AT?) technical reference manual. IBM used an 8048 (or some
such) at both ends of the keyboard cable.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

 

[bombi]

I think we have same problem, but I got it today!
The wirring is same as HP HEDS-5500 dual channel encoder
Pin 1:GND 2:X 3:ChA 4:5V+ 5:CHB.

But I have problem on my encoder disk!
How much resolution is for HP 5001-6902 encoder disk?

 

[CWatters]

"adrian" <adrian@bonni.freeserve.co.uk> wrote in message
news:463826e2.0410150714.73071f80@posting.google.com...

I want to do a home based project on getting a pic chip to read a
keyboard. What kit should I use - is a usb one a good option?

I would use a standard PC AT/PS2 keyboard...

The protocol is well documented all over the net... Examples..

http://www.beyondlogic.org/keyboard/keybrd.htm
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/PS2/ps2.htm
http://govschl.ndsu.nodak.edu/%7Eachapwes/PICmicro/index.html

and the code you need for the PIC already exists.. Examples...

http://www.electronic-engineering.ch/microchip/projects/projects.html
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/code/ps2/Host.html

The above may not be the BEST examples so find your own. Hint: try posting
on a PIC users forum.

 

[CWatters]

"adrian" <adrian@bonni.freeserve.co.uk> wrote in message
news:463826e2.0410150714.73071f80@posting.google.com...

I want to do a home based project on getting a pic chip to read a
keyboard. What kit should I use - is a usb one a good option?

I would use a standard PC AT/PS2 keyboard...

The protocol is well documented all over the net... Examples..

http://www.beyondlogic.org/keyboard/keybrd.htm
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/PS2/ps2.htm
http://govschl.ndsu.nodak.edu/%7Eachapwes/PICmicro/index.html

and the code you need for the PIC already exists.. Examples...

http://www.electronic-engineering.ch/microchip/projects/projects.html
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/code/ps2/Host.html

The above may not be the BEST examples so find your own. Hint: try posting
on a PIC users forum.

 

[DAW]

First type "GOOGLE", then begin typing your questions.......

"Olive" <olivierdominguez@free.fr> wrote in message
news:f1b21c8c.0410151035.615637a7@posting.google.com...

I'm French electronic student, I need some informations about airborne
communications and data management solutions to airlines.
I need also technicals documentations aviation electronics systems,
electromagnetic compatibility, transmissions capacities.
Please send me your contacts or some internet links, technical Books,
etc....



Thank you.

 

[Tim Auton]

szweda@gmail.com (Roy Szweda) wrote:

Please could someone tell me whether it is better to run a portable
music player like MiniDisc or CD Walkman with rechargeable batteries
or non-rechargeables?

I get the feeling that these gadgets are a mite too voltage sensitive
and don't work for as long with rechargeables.... which fall to a
voltage insufficient to run the gadget quicker.

Define "best".


Tim
--
Copyright, patents and trademarks are government-granted, time-limited monopolies.
Intellectual property does not exist.

 

[Nicholas O. Lindan]

"Roy Szweda" <szweda@gmail.com> wrote

Please could someone tell me whether it is better to run a portable
music player like MiniDisc or CD Walkman with rechargeable batteries
or non-rechargeables?

I get the feeling that these gadgets are a mite too voltage sensitive
and don't work for as long with rechargeables

Sort of depends on the gadget, doesn't it? And the usage cycle. And
how you feel about throwing out batteries. And how long you are away
from mains power. And .... and ... and ...

There is no definitive answer. Use what seems to work best for you
and forget about it.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

 

[CWatters]

"Roy Szweda" <szweda@gmail.com> wrote in message
news:64249a23.0410181259.3628486f@posting.google.com...

Please could someone tell me whether it is better to run a portable
music player like MiniDisc or CD Walkman with rechargeable batteries
or non-rechargeables?

I get the feeling that these gadgets are a mite too voltage sensitive
and don't work for as long with rechargeables.... which fall to a
voltage insufficient to run the gadget quicker.

The voltage curve for modern rechargable cells is quite flat and doesn't
fall until nearly all the capacity has been used. If their lower voltage was
a problem you would expect them to either not work at all or cut off very
quickly (few mins).

I believe NiCad rechargables are also quite a bit lower capacity than
Alkaline cells like Duracell.

Try the newer NiMH cells with a capacity of circa 2300+ mAH. They last
nearly 4 times as long as older 600mAH NiCad cells.

 

[sds]

Désolé je peux pas t'aider pour ça.
T'as vachement de réponses constructives pour le moment, des fois on
s'imagine pas ŕ quel point c'est dur de trouver des infos tant qu'on n'a
pas cherché...
Sur un newsgroup anglophone c'est pas forcément une bonne chose de laisser
savoir qu'on est francais, beaucoup d'anglophones sont archi-cons avec les
français.

Olive wrote:

I'm French electronic student, I need some informations about airborne
communications and data management solutions to airlines.
I need also technicals documentations aviation electronics systems,
electromagnetic compatibility, transmissions capacities.
Please send me your contacts or some internet links, technical Books,
etc....



Thank you.

 

[Gareth Rowlands]

In message <41766be3$0$48014$ed2e19e4@ptn-nntp-reader04.plus.net>
Martin Underwood wrote:

LEDs as film lights? Sounds highly intriguing.

Those red or cyan washes used on the glass parts of the 'Watchdog' set
are from LED sources. The fun bit is that the brightness is controlled
by high frequency pulse-width modulation, so Daniel may have issues with
anything fitted with a shutter, hint-hint !

Cheers,

G.

--
http://www.rat.org.uk gareth at lightfox dot plus dot com

 

[Richard Crowley]

"Deep Reset" wrote ...

I saw a Beyonce video ("Crazy in love" maybe) with a rooftop, twilight
scene with what looked like flat discs of white leds maybe a foot in
diameter, a bit like continuous ring-flash giving flat lighting.

Described by one of the regulars on rec.video.production a
year or two ago. He made a large disk that fit around the lens
and laid "light-rope" around in a spiral to create a large flat
light for a special shot.