magnetic field

Jim Thompson wrote:
On Tue, 05 Jul 2005 18:58:09 +0200, Zak <jute@zak.invalid> wrote:

"Staged" doesn't happen. The output is DC. The only way would be to
add a switching device at the end of a 4X and you have no power to run
it.

What about a spark gap?

Thomas

For what purpose?
Make DC into AC, or more accurately, into pulsed DC. But I have a
feeling at least half the voltage gets lost doing this. And will spark
gaps scale indefinitely in voltage? Probably not.


Thomas
 
On Mon, 04 Jul 2005 11:15:22 +0000, CWatters wrote:

Nice example of how the real world is full of
surprises.
Not quite what the plant's ATM guy said at the time :)

--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
(Stephen Leacock)
 
Robert Clark wrote:
Key for lifter drive becoming a generally useful propulsion method is
an electrical power source lightweight enough to be lifted by the
lifter dirve. Electrostatic high voltage generators may prove to an
answer for such a power source.
Electrostatic high voltage generators have existed since the 18th
century. They were earlier called electrostatic influence machines.
This page of Antonio Carlos M. de Queiroz calcutes the current that can
be generated by an electrostatic influence machine:

Maximum electric field.
http://www.coe.ufrj.br/~acmq/efield.html

(For anyone who had the same problem as I did opening this site, you
can get the Google cached version here:

Maximum electric field.
http://64.233.161.104/search?q=cache:Su6AOXBIC9EJ:www.coe.ufrj.br/~acmq/efield.html)

Note that it is dependent on the product of the dielectric constant
of air and the breakdown voltage of air.
Then since the dielectric constant of the air and vacuum are about
the same but the breakdown voltage of the vacuum is immeasurably
high, you can achieve much higher currents enclosing the device in a
vacuum.
Various types of electrostatic generators are described on this page
of de Queiroz:

Electrostatic Machines.
http://www.coe.ufrj.br/~acmq/electrostatic.html

Especially useful for our methods might be the Wimhurst, Wehrsen,
Holtz, or Bonetti machines. I believe these devices would be able to
deliver more current and therefore greater wattage for our application
than a Van de Graaff generator.
Another interesting possibility might be the voltage doubler. As the
name implies it doubles the applied voltage with each cyclic turn of
the rotors:

The Bohnenberger machine.
http://www.coe.ufrj.br/~acmq/bohnenberger.html

Take a look at the graph on this page to see how the voltage is
doubled at each cycle. The doublers are limited in voltage in air by
the sparking that is produced. The voltage possible in vacuum should be
markedly higher.
Another possibility might the generators that use a vertical cylinder
as a rotor. From de Queiroz "Maximum electric field" page you see the
current produced is proportional to the surface area of the rotor and
the speed of rotation. But there are limits to the rotational speed for
real materials since they would fall apart from the internal stresses.
Keeping the speed low but increasing the radius of a flat disc raises
the same problem because the speed on the edge of the disk will be
higher. However, a vertical cylinder solves this since you get
increased surface area by making the cylinder long while the internal
stresses from the rotation are only operating radially.
The key factor in using an electrostatic generator for the power
supply is that they can serve as both the source of the electrical
power and the source of the high voltage generation - you don't need
separate power supply and transformer.
That they act as source for high voltage is known, but the reason they
can act as the power source for our application is they are in effect
flywheel batteries. Then at launch you induce the rotors to spin at
high speed by either mechanical or electrical means and as with any
flywheel they would act as a means of power storage. Note that with the
most advanced flywheel batteries you enclose the flywheel in vacuum to
keep the time the flywheel spins to a longer period by reducing air
friction, and they also use magnetic bearings to reduce the friction
from the support of the rotor. Then this dovetails nicely with the
requirement to have them in vacuum to increase voltage attained.
A file in the Yahoo Lifters group calculates remarkable power
generation for a moderately sized vacuum electrostatic generator:

Lifters.
http://groups.yahoo.com/group/Lifters/

The file named "Electrostatic HV Supply.PDF" appears in the Files
section in that group. It was copied from a book on high voltage
generation and claims for a generator operating in high vacuum with 50
rotors, 4 feet in diameter rotating at 4,000 RPM could generate 1 MV
and 7 megawatts of power. Note that key in its being able to deliver
this power is the rotors operating in vacuum where much higher voltage
gradients are possible, 1 MV/cm or 100 MV/m in this case. In air you
might be able to get only 3 MV/m. Then assuming approx. a 1 to 1
thrust(in grams) to power(in watts) ratio, this could lift 7,000 kg.
Key would be making the rotors light weight. Then work on advanced
flywheel batteries that use carbon composites for the flywheel would be
helpful here:

Composite Rotor Lifetime Testing.
http://www.utexas.edu/research/cem/composite%20rotor%20testing.html

Flywheel Energy Storage.
http://www.upei.ca/~physics/p261/projects/flywheel1/flywheel1.htm

Flywheel Basics Tutorial.
http://rpm2.8k.com/basics.htm




Bob Clark
On this Powerlabs.org page I saw discussed use of a Dremel grinding
tool to generate high revolutions per second:

PowerLabs High Speed CD-Rom Experiments.
http://www.powerlabs.org/cdexplode.htm

This tool can generate 35,000 RPM or nearly 600 revolutions per second.
Perhaps this can be used to increase the current generated by an
electrostatic generator by increasing the rotation speed. See the
formula on de Queiroz's page for the current
generated:

Maximum electric field.
http://www.coe.ufrj.br/~acmq/efield.html

De Queiroz gives an example here of a rotor with 13 cm, 5", outer
diameter with a rotation speed of 40 revolutions per second generating
36 microamps. So at 600 turns/sec using the formula there should be 15
times the current or 540 microamps. Note too that in the example there
is a 9 cm inner diameter which reduces the surface area by about 1/2.
So for a solid disk at 13 cm diameter there would be about 1000
microamps, 1 milliamp.
Dremel grinding tools are available for reasonably low prices. Here's
one for $29.00 US:

Wholesale Dremel Type Rotary Electric Grinder kit NEW.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29528&item=4389954711


You could also increase the current by increasing the number of rotors
(but see the caution below.)
Note that the idea is to see if these electrostatic generators could
provide a self-contained power unit for a lifter. But at first we want
to see if they can supply sufficient power/current to raise just the
lifter. So in the first experiments you just use already existing
electrostatic generators on the ground, which are not optimized to be
lightweight.
Then we also want to see how the energy of rotation is stored and
converted into electrostatic energy. So once it is confirmed the
generators can provide sufficient power, you disconnect the Dremel to
see how long the rotor can spin fast enough to provide sufficient power
to raise the lifter.
Note that these first experiments are done in air so the air friction
will significantly reduce the rotation time once the Dremel is
disconnected. Later the idea would be to contain the rotor in vacuum.
This will increase the rotation time and at the same time increase the
voltage possible 30 to 50 times. (Note that to get this voltage
increase, it has to be a very high vacuum since reducing the pressure
can actually decrease the breakdown voltage until very high vacuum is
reached.)

CAUTIONS!
Note that on the Powerlabs page they were attempting to cause a CD disk
to disintegrate by spinning at the highest speed of the Dremel. In
*this* experiment they had to additionally strike the spinning CD with
another CD to get the spinning CD to shatter. But there have been cases
where CD's have shattered at lower speeds than 35,000 RPM. Also after
rotating at this speed for some time, the CD would suffer stress
fatigue and would become even more likely to shatter. So even if you
spin a rotor at a high speed for some time, at a later time it can
still shatter at that very same speed.
Acrylic if that is used for the rotor probably would have comparable
tensile strength as a CD. It is *strongly* advised that the rotor be
gradually brought up to higher speeds stepwise. And it is *strongly*
advised that the rotor be behind a protective wall during these
experiments. You can view the experiment by video camera or by mirrors
(metal so as not to shatter.) In the Powerlabs experiments the
experimenter held the Dremel with the spinning CD out in front of him.
This is strongly disadvised.
Note also if you use more than one rotor on a single Dremel this could
cause wobbling which could put more stress on the rotors increasing the
chance of shatter and also making the directions the shards would go
more unpredictable.
Also, if you increase the diameter of the rotors the speed at the edge
of the rotor is also increased thereby increasing the chance of
shattering. Moreover, the Dremels are actually designed for rather
small diameter grinding attachments. Large diameter rotors could damage
the Dremel motor.


Bob Clark
 
"Timbo" <carrfamily@mindspring.com> wrote in message
news:TFUye.18406$eM6.11194@newsread3.news.atl.earthlink.net...
I've had it! I've put up all kinds of physical obstacles to prevent
squirrels from getting to the bird feeder outside my study window, but
the
gymnastic squirrels keep outsmarting me and mastering the obstacles.

I'd like to be able to push a button on my study desk when I see a
squirrel
climbing up to the feeder, and have an ear-splitting horn next to the
feeder
blast him.

I've googled (actually froogled) horns, but don't know what I'm
seeing. I
would be grately deepful if you could recommend a relatively
inexpensive
setup.

Thanks
Tim Carr
Seems like you can't post to the right places. This definitely wasn't
for that .jobs NG. Xposted to sci.electronics.misc

First off, you have to get a natural predator of squirrels. I've never
seen squirrels on campus at work because we have a nesting pair of
hawks. This time of year they abandon the nest and let junior fend for
himself. We see bits of critters laying around under the trees. Good
riddance.

Another approach is to use your own enginuity. Try trapping the little
thief. What to do with him when you catch him is another matter.

Maybe you could impeove your sharpshooting skills by using a BB gun.
 
Watson A.Name - "Watt Sun, the Dark Remover" wrote:

Maybe you could impeove your sharpshooting skills by using a BB gun.
Back in the day, "shooting squirrels" was a popular activity on campus.
 
Get a cat, or a dog that hates critters.

I have a cairn terrier that spends most of its time in the back yard.
This dog chases up to anything or anyone that even approaches the yard.
It is very territorial. It gets so agitated, that it charges the fence,
and bites and pulls on the fence wires to try to get at the critter!

Nothing or anyone cuts in to our yard, especialy when this dog is
around. If it is in the house, it starts having a fit if someone or
something comes on to our property.

Jerry G.
======
 
John Larkin wrote:
On Fri, 08 Jul 2005 15:53:08 +0000, Guy Macon
http://www.guymacon.com/> wrote:




The best way to find a consultant is through Google. Let's
say you want the very best consultant who specializes in
electronics; Google search on 'electrical engineer resume' or
'electronics engineer resume' or 'electronic engineer resume':

http://www.google.com/search?q=electrical+engineer+resume
http://www.google.com/search?q=electronics+engineer+resume
http://www.google.com/search?q=electronic+engineer+resume

Google has a sophisticated algorithm that is quite good at
identifying the resume of the very best engineer and putting
it at or near the top of the results listing.



Such a coincidence: the very first search pulls up

http://www.guymacon.com/

who, technically, isn't an engineer at all. Sounds like Google
actually has a rotten algorithm.

More vanity and stupid web tricks. What a pretentious fathead!

John
You may have overestimated the search engine,

For example, If you Google "poor to nonexistent" engineer:
http://www.google.com/search?hl=en&lr=&safe=off&q=%22poor+to+nonexistent%22+engineer&btnG=Search

Just an observation.

Frank Raffaeli
http://www.aomwireless.com/
 
Sounds like you may have some "google envy", whereas another individual
shows up more on google that you do! WTF, who cares, get over it!

"Frank Raffaeli" <SNIPrf_man_frTHIS@yahoo.com> wrote in message
news:1120858144.503205.322690@g44g2000cwa.googlegroups.com...
John Larkin wrote:
On Fri, 08 Jul 2005 15:53:08 +0000, Guy Macon
http://www.guymacon.com/> wrote:




The best way to find a consultant is through Google. Let's
say you want the very best consultant who specializes in
electronics; Google search on 'electrical engineer resume' or
'electronics engineer resume' or 'electronic engineer resume':

http://www.google.com/search?q=electrical+engineer+resume
http://www.google.com/search?q=electronics+engineer+resume
http://www.google.com/search?q=electronic+engineer+resume

Google has a sophisticated algorithm that is quite good at
identifying the resume of the very best engineer and putting
it at or near the top of the results listing.



Such a coincidence: the very first search pulls up

http://www.guymacon.com/

who, technically, isn't an engineer at all. Sounds like Google
actually has a rotten algorithm.

More vanity and stupid web tricks. What a pretentious fathead!

John

You may have overestimated the search engine,

For example, If you Google "poor to nonexistent" engineer:

http://www.google.com/search?hl=en&lr=&safe=off&q=%22poor+to+nonexistent%22+engineer&btnG=Search

Just an observation.

Frank Raffaeli
http://www.aomwireless.com/
 
Jim Douglas wrote:
Frank Raffaeli wrote...

You may have overestimated the search engine,

For example, If you Google "poor to nonexistent" engineer:

http://www.google.com/search?hl=en&lr=&safe=off&q=%22poor+to+nonexistent%22+engineer&btnG=Search

Just an observation.
Nope, Google is doing exactly what it's supposed to do.
I wrote those words because they are true, and anyone hiring me
needs to know what i am excellent at and what I am poor at.

Sounds like you may have some "google envy", whereas another individual
shows up more on google that you do! WTF, who cares, get over it!
Google Envy... That's a good one! Maybe he's like Larkin,
intimidated by his technical and social superiors.
 
Guy Macon wrote:
Jim Douglas wrote:

Frank Raffaeli wrote...

You may have overestimated the search engine,

For example, If you Google "poor to nonexistent" engineer:

http://www.google.com/search?hl=en&lr=&safe=off&q=%22poor+to+nonexistent%22+engineer&btnG=Search

Just an observation.

Nope, Google is doing exactly what it's supposed to do.
I wrote those words because they are true, and anyone hiring me
needs to know what i am excellent at and what I am poor at.

Sounds like you may have some "google envy", whereas another individual
shows up more on google that you do! WTF, who cares, get over it!

Google Envy... That's a good one! Maybe he's like Larkin,
intimidated by his technical and social superiors.
Nah,

Larkin's a pretty sharp guy. I couldn't resist taking a poke at the
search engine comments in your OP, which were, I presume, in good fun
.... as were mine.

Frank Raffaeli
http://www.aomwireless.com/
 
\CWatters wrote:
Google Envy... That's a good one!

Na, can't be that. Otherwise well just try searching for "dumb terminal
engineer" see who's number 3 on the list :)

http://www.google.com/search?hl=en&q=terminal+dumb+engineer

Only joking!
<big smile>

I loved those old ADM-3 Dumb Terminals. What a great product name!
 
On Fri, 08 Jul 2005 22:12:13 GMT, "CWatters"
<colin.watters@pandoraBOX.be> wrote:

Google Envy... That's a good one!

Na, can't be that. Otherwise well just try searching for "dumb terminal
engineer" see who's number 3 on the list :)

http://www.google.com/search?hl=en&q=terminal+dumb+engineer

Only joking!
Bwahahahahaha!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
CWatters wrote:
Google Envy... That's a good one!

Na, can't be that. Otherwise well just try searching for "dumb terminal
engineer" see who's number 3 on the list :)

http://www.google.com/search?hl=en&q=terminal+dumb+engineer

Only joking!
Or dumb engineering diva
http://www.google.com/search?hl=en&lr=&safe=off&q=dumb+engineering+diva&btnG=Search

Gosh, maybe I am envious. ;-)

Frank Raffaeli
http://www.aomwireless.com/
 
On Fri, 08 Jul 2005 22:12:13 +0000, CWatters wrote:

Google Envy... That's a good one!

Na, can't be that. Otherwise well just try searching for "dumb terminal
engineer" see who's number 3 on the list :)

http://www.google.com/search?hl=en&q=terminal+dumb+engineer
Oh, crap! He can't keep a job!

Only joking!
I'm not.

--
Keith
 
"St. John Smythe" <UndisclosedRecipient@privacy.net> wrote in message
news:dalnt7$59i$9@n4vu2.n4vu.com...
Watson A.Name - "Watt Sun, the Dark Remover" wrote:

Maybe you could impeove your sharpshooting skills by using a BB gun.

Back in the day, "shooting squirrels" was a popular activity on
campus.

When I went up north to Mammoth Lakes, My dad's friend's son took me to
the dump to get some target practice on the rats.
 
Watson A.Name - "Watt Sun, the Dark Remover" wrote:

"Timbo" <carrfamily@mindspring.com> wrote in message
news:TFUye.18406$eM6.11194@newsread3.news.atl.earthlink.net...
I've had it! I've put up all kinds of physical obstacles to prevent
squirrels from getting to the bird feeder outside my study window, but
the
gymnastic squirrels keep outsmarting me and mastering the obstacles.

I'd like to be able to push a button on my study desk when I see a
squirrel
climbing up to the feeder, and have an ear-splitting horn next to the
feeder
blast him.

I've googled (actually froogled) horns, but don't know what I'm
seeing. I
would be grately deepful if you could recommend a relatively
inexpensive
setup.

Thanks
Tim Carr

Seems like you can't post to the right places. This definitely wasn't
for that .jobs NG. Xposted to sci.electronics.misc

First off, you have to get a natural predator of squirrels. I've never
seen squirrels on campus at work because we have a nesting pair of
hawks. This time of year they abandon the nest and let junior fend for
himself. We see bits of critters laying around under the trees. Good
riddance.

Hawks also feed on the very birds the poster is trying to attract as
well as small domestic animals. Besides, how does one invite a pair
of hawks to nest near ones yard? Perhaps one can mount stuffed hawks
near the feeder?

Another approach is to use your own enginuity. Try trapping the little
thief. What to do with him when you catch him is another matter.
In the county where I live, it is illegal to trap squirrels unless you
are licensed or they are inside your home.

Maybe you could impeove your sharpshooting skills by using a BB gun.
That's the best idea yet
 
<Bingo@invalid.org> wrote in message
news:cvdvc15cf4nr7nckq2e3i5rd81i3sm0ce6@4ax.com...
Watson A.Name - "Watt Sun, the Dark Remover" wrote:


"Timbo" <carrfamily@mindspring.com> wrote in message
news:TFUye.18406$eM6.11194@newsread3.news.atl.earthlink.net...
I've had it! I've put up all kinds of physical obstacles to
prevent
squirrels from getting to the bird feeder outside my study window,
but
the
gymnastic squirrels keep outsmarting me and mastering the
obstacles.

I'd like to be able to push a button on my study desk when I see a
squirrel
climbing up to the feeder, and have an ear-splitting horn next to
the
feeder
blast him.

I've googled (actually froogled) horns, but don't know what I'm
seeing. I
would be grately deepful if you could recommend a relatively
inexpensive
setup.

Thanks
Tim Carr

Seems like you can't post to the right places. This definitely
wasn't
for that .jobs NG. Xposted to sci.electronics.misc

First off, you have to get a natural predator of squirrels. I've
never
seen squirrels on campus at work because we have a nesting pair of
hawks. This time of year they abandon the nest and let junior fend
for
himself. We see bits of critters laying around under the trees.
Good
riddance.

Hawks also feed on the very birds the poster is trying to attract as
well as small domestic animals. Besides, how does one invite a pair
of hawks to nest near ones yard?
You build or buy an artificial nest for them. Duh.
http://www.conservation.state.mo.us/nathis/woodwork/ww5/
http://www.owlpages.com/owlboxes.html
http://www.bbc.co.uk/nature/animals/wildbritain/wildinyourgarden/gardens
/fsab_providing.shtml

[snip]

Maybe you could improve your sharpshooting skills by using a BB gun.

That's the best idea yet
Or else put rodent poison out for the critters. I know that warfarin
kills rats, but I don't know if there is a poison specific to squirrels.
 
On 9 Jul 2005 07:44:47 -0700, rgregoryclark@yahoo.com wrote:

John Larkin wrote:
On 7 Jul 2005 10:22:15 -0700, rgregoryclark@yahoo.com wrote:

John Larkin wrote:
On 6 Jul 2005 21:07:52 -0700, rgregoryclark@yahoo.com wrote:

John Larkin wrote:

...
Suppose you had a light, high-voltage, high-current power supply. You
connect one power supply terminal to the lifter body. Where do you
connect the other?

John

This page shows construction of a lifter:

How to build an HexaLifter for your experiments.
http://jlnlabs.imars.com/lifters/hexalifter/index.htm

One lead from the power supply is connected to wires at the top of the
lifter. The other lead is connected to metal foil at the bottom. You
have insulators separating the wires from the foil. Then the air
between the wires and foil serves as a dielectric for a capacitor. The
asymmetric geometry of the two sides of the capacitor, the wires
compared to the flat metal foil, causes a flow of ions from one to the
other.


Bob Clark


But that's not the way the hexalifter is wired. External (grounded)
+HV is run through a wire from the power supply to the upper wire
array, and no connection is made to the foil thingie.

If you did make an unthethered lifter, with no return current path to
ground, its ion emission would quickly build up a huge net potential
on the whole structure. Has anybody ever got this to work?

There's a much more efficient way to convert electrical energy to
lift; a helicopter rotor.

John

Perhaps the second wire connection is not visible on that page, but
all lifters are made in this same way. See for example this page:


The hexlifter page says that one wire supplies hv to the lifter's
upper wire array, and that it "is maintained with three thin nylon
wires to the styrofoam base plate" which doesn't sound conductive to
me.

So the single uplink wire replentishes the charge lost by creating
ions. If you float the power supply onboard, and still eject ions, a
huge charge will quickly build up on the structure.

Has anybody ever built a self-powered, unthethered lifter?

John

John, I really don't see why you're arging this point.
Because I'm an engineer.

The "thin nylon
wires" are used to hold the lifter in place so it won't fly away. They
are not the conducting wires for the power supply. Lots of amateurs
have made lifters with no tethers: they usually fly up far enough to
disconnect the power supply wires or damage the lifter.
But can they fly with *no* wires?


John
 
On Fri, 08 Jul 2005 22:21:32 +0000, Guy Macon
<_see.web.page_@_www.guymacon.com_> wrote:

\CWatters wrote:

Google Envy... That's a good one!

Na, can't be that. Otherwise well just try searching for "dumb terminal
engineer" see who's number 3 on the list :)

http://www.google.com/search?hl=en&q=terminal+dumb+engineer

Only joking!

big smile

I loved those old ADM-3 Dumb Terminals.
---
Kindred spirits?

--
John Fields
Professional Circuit Designer
 
On Fri, 08 Jul 2005 21:43:21 +0000, Guy Macon
<_see.web.page_@_www.guymacon.com_> wrote:

Jim Douglas wrote:

Frank Raffaeli wrote...

You may have overestimated the search engine,

For example, If you Google "poor to nonexistent" engineer:

http://www.google.com/search?hl=en&lr=&safe=off&q=%22poor+to+nonexistent%22+engineer&btnG=Search

Just an observation.

Nope, Google is doing exactly what it's supposed to do.
I wrote those words because they are true, and anyone hiring me
needs to know what i am excellent at and what I am poor at.

Sounds like you may have some "google envy", whereas another individual
shows up more on google that you do! WTF, who cares, get over it!

Google Envy... That's a good one! Maybe he's like Larkin,
intimidated by his technical and social superiors.
---
First you get yourself into a fix by flaming Win, and come out of it
by electing to apologize and kiss ass 'til the cows come home, and now
you're going after Larkin? You're so far to the rear of where he is,
technically and socially, and everyone else that you've chosen to go
after, that it seems what you're looking for is a series of good
whippings to atone for your excursions into stupidity and prove to
yourself that you're at least worth being whipped.

--
John Fields
Professional Circuit Designer
 

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