magnetic field

[Noah Little]

Dave wrote:

Another thing.
Suppose I set the function gen to 10Hz Sine Wave.. and I use
some coils in the output, can the coil produce magnetic fields?

It not only can, you would be hard put to prevent it. But how much
field strength do you need?

 

[CWatters]

"Etantonio" <etantonio@gmail.com> wrote in message
news:467ddbce.0505170107.483894e2@posting.google.com...

Good Morning,
I've a Gericom Webshox laptop, it is of 2001, I changed the battery
but it is still not working, the problem seems to be that the 15 volts
coming from power supply don't reach the battery, they seems stopped
from an 8-pin dual in line IC named 4431 1503 that I don't know who is
the manufacturer, I search for it on internet but with no results.
To solve the problem I need the following information :

1) Who is the producer of this IC 4431

Try this one...

http://alfa.iele.polsl.gliwice.pl/elenota/Vishay/72092.pdf

 

[Uncle Al]

Robert Clark wrote:

The ioncraft is a method proposed for decades for aircraft and
spacecraft propulsion:
[snip]

It works by ionizing the air by electrical charge thereby creating an
air flow between the electrodes, generating thrust. There are several
examples of these, called "lifters", made by amateurs:
[snip crap]

Hey stooopid, thrust in this case varies as surface area but payload
varies as volume. The demo is bullshit when applied to the real world
product.

The problem with them is their power supplies are much heavy than the
weight they can lift. But why not leave the power supply on the ground
and connect it to the craft by long power cables?
[snip]

Dumber than a used tampon. Hey stooopid, rockets don't launch
straight up - not for long they don't. Getting 100 miles high is a
no-brainer. Scaled Composites mostly pulled it off ad hoc. Getting to
25,000 mph at 100 miles altitude is something else again.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

 

[George Dishman]

"Robert Clark" <rgregoryclark@yahoo.com> wrote in message
news:1116359611.618267.84110@g47g2000cwa.googlegroups.com...

The question: how much power would be lost by
sending it along a 100km long cable?

Choose your voltage. Divide power P by voltage V to
get current I. Loss is I^2 * R. You need to work
out R using the resistivity of the material and the
length. Remember to count both wires.

George

 

[Charles Jean]

On Tue, 17 May 2005 22:21:34 +0100, "George Dishman"
<george@briar.demon.co.uk> wrote:

"Robert Clark" <rgregoryclark@yahoo.com> wrote in message
news:1116359611.618267.84110@g47g2000cwa.googlegroups.com...

The question: how much power would be lost by
sending it along a 100km long cable?

Choose your voltage. Divide power P by voltage V to
get current I. Loss is I^2 * R. You need to work
out R using the resistivity of the material and the
length. Remember to count both wires.

George

I assume you will be running two cables for the power, a hot and a
return. How about insulation of the wires from each other? Is the
conductor here the carbon fiber itself or some metal? Then calculate:
a) the total mass of 100,000 ft. of the cables
b) the electrical resistance of 100,000 ft. of the the conductors
c) power loss through the conductors
d) temperature rise through the conductors


"There are known knowns. These are things that we know we know.
There are known unknowns. That is to say, there are some
things that we know we don't know. But there are also unknown
unknowns. These are things we don't know we don't know."
-Secretary of Defense Donald Rumsfeld

 

[Luhan Monat]

"There are known knowns. These are things that we know we know.
There are known unknowns. That is to say, there are some
things that we know we don't know. But there are also unknown
unknowns. These are things we don't know we don't know."
-Secretary of Defense Donald Rumsfeld

Rumsfeld must have taken EST. That was part of the course introduction.

--
Luhan Monat: luhanis(at)yahoo(dot)com
http://members.cox.net/berniekm
"Any sufficiently advanced magick is
indistinguishable from technology."

 

[Jim Thompson]

On Tue, 17 May 2005 16:12:41 -0700, Luhan Monat <x@y.z> wrote:

"There are known knowns. These are things that we know we know.
There are known unknowns. That is to say, there are some
things that we know we don't know. But there are also unknown
unknowns. These are things we don't know we don't know."
-Secretary of Defense Donald Rumsfeld

Rumsfeld must have taken EST. That was part of the course introduction.

It's deja vu all over again ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Rich Grise]

On Tue, 17 May 2005 12:53:31 -0700, Robert Clark wrote:

The problem with them is their power supplies are much heavy than the
weight they can lift. But why not leave the power supply on the ground and
connect it to the craft by long power cables?

Because 100 miles of copper power cable is even heavier?

Thanks,
Rich

 

[John Larkin]

On Tue, 17 May 2005 16:12:41 -0700, Luhan Monat <x@y.z> wrote:

"There are known knowns. These are things that we know we know.
There are known unknowns. That is to say, there are some
things that we know we don't know. But there are also unknown
unknowns. These are things we don't know we don't know."
-Secretary of Defense Donald Rumsfeld

Rumsfeld must have taken EST. That was part of the course introduction.

We had a lot of them here. We called them estholes:

"Yes, I'm standing on your face, and I'm wearing cleats, but if you
really want to be miserable, it's your problem."

John

 

In article <pan.2005.05.17.23.40.11.949817@example.net>, Rich Grise <richgrise@example.net> writes:

On Tue, 17 May 2005 12:53:31 -0700, Robert Clark wrote:

The problem with them is their power supplies are much heavy than the
weight they can lift. But why not leave the power supply on the ground and
connect it to the craft by long power cables?

Because 100 miles of copper power cable is even heavier?

I've been wondering how long it'll take before somebody states the

obvious.

Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"

 

[Ben Bradley]

On Tue, 17 May 2005 23:39:04 GMT, Rich Grise <richgrise@example.net>
wrote:

On Tue, 17 May 2005 12:53:31 -0700, Robert Clark wrote:

The problem with them is their power supplies are much heavy than the
weight they can lift. But why not leave the power supply on the ground and
connect it to the craft by long power cables?

Because 100 miles of copper power cable is even heavier?

And at Monster Cable(TM)(R) prices it's hugely expensive.

Thanks,
Rich

-----
http://mindspring.com/~benbradley

 

[Ban]

Robert Clark wrote:
snip childish BS
I remember being 13yrs. old and discussing things like this with my
roommates at public school. It is a nice exercise being kids, but a grown up
person should switch on the probability check before x-posting to all these
NGs.
--
ciao Ban
Bordighera, Italy

 

[CWatters]

"Dave" <davidqanta@yahoo.com> wrote in message
news:1116370259.813307.103920@g49g2000cwa.googlegroups.com...

Anyway. What are the uses of Function Generator
generally, pls. mention 12 applications. Tnx.

We don't normally answer homework questions but....

Function generator and signal generators are typically used to simulate a
signal(s) from a source that can't be used for some reason:

Examples:

The real source is not available or not accessible (eg Mars rover sensor) .
It's too expensive to use the normal source (Ditto)
The real source can't be controlled (eg synchronised to other events)
It's output isn't repeatable enough (eg Earthquake sensor)

 

[bz]

rgregoryclark@yahoo.com wrote in news:1116393655.205094.108590
@f14g2000cwb.googlegroups.com:

Rich Grise wrote:
On Tue, 17 May 2005 12:53:31 -0700, Robert Clark wrote:

The problem with them is their power supplies are much heavy than
the
weight they can lift. But why not leave the power supply on the
ground and
connect it to the craft by long power cables?

Because 100 miles of copper power cable is even heavier?

Thanks,
Rich

Aluminum is almost always used for high voltage power lines. This is
because of its lower weight:

Aluminium's Electrical Uses.
http://www.world-aluminium.org/applications/electrical/

At 2700 kg/m^3, it's weight is only 50% more than carbon fiber. So a 4
cm wide, 100km long aluminum cable would only weigh 340,000 kg. This
compares to 2 million kg for the space shuttle with solid rocket
boosters.
While carbon fiber is electrically conductive, you might want to use
aluminum for higher conductivity (lower power loss). Then you would use
carbon fiber to provide strength for the cable.

How much current is going to flow? If those aluminum wires are 3 cm in
diameter, the resistance of two 100 km wires is going to be about 750 ohms.

Most of your power is going to end up heating your wire.




--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+sp@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[Tomi Holger Engdahl]

"Dave" <davidqanta@yahoo.com> writes:

I need a function generator with 50 volts. Normal ones only have
9 volts. Why do they limit it to just 9

The limit of the outpu voltage range is generally
mostly limited by the operating voltage used in the
function generator. That 9V output voltage can be easily generated
with +-12V power supply. That's the operating voltage range
the ICs used in function generally work.
Around +-12V supply is suitbale for many operational
amplifier ICs. So there is good selection of
suitable output amplifier ICs for that voltage
range available.

If the funtion generator maker would have wanted
higher output voltage range, he would have needed to
use higher operating voltages inside the device
and possibly needed much more special ICs to
implement it. This would have made the function
generator propably considerably more expensive.

and how much difficult
to make it 50 or so.

If ou have a suitable amplifier that has this
output voltage rating, and amplification of 6 or more,
you will get the voltage you need by just feeding
the function generator signal to it and get
the suitable signal level from output.
Make sure that the amplifier you have can
properly work at the frequencies you need signals at,
the bandwidth of amplifier should be considerably
higher then your needed frequency if you want to
avoid the amplifier to distort your triangle and
square wave signals.

High voltage amplifier circuits that can
operate from DC to high frequencies tend to
be expensive.

If you operata at normal audio frequencies (20 Hz to 20 kHz),
a suitable hifi amplifier could be one possibility
as the amplifier. If you want 50V output voltage,
you would need to select a quite powerful PA amplifier.
50V to 8 ohms is 312.5W and when connected to 4 ohms
power is 625W. If you use norma audio amplifir, you would
be looking for amplifier in the voltage range.

Other amplifiers when working with audio frequencies
could be propably those amplifiers designed to drive
distributed speakers that connect to 70V or 100V line.
Those should nicely drive 50V to output when not
in full power.. Size the amplifier based on the
power you need. This kind of amplifiers has
limitations on bandwidth (no lowest bass and
the highest audio frequencies coudl be attenuated).

If your current needs on output are low and you
don't need very low frequencies / DC output, then
in some cases just a suitable step-up transformer
connected to the output of function generator could
work. Or at somewhat higher powers, a normal audio
power amplifier (several watts to tens of watts) driving
a suitable step-up transformer could be one way to do things.
I have used the audio amplifier + transformer when I
needed to generae quite high voltage telephone ring signals at
http://www.epanorama.net/circuits/telephone_ringer.html

Another thing.
Suppose I set the function gen to 10Hz Sine Wave.. and I use
some coils in the output, can the coil produce magnetic fields?

A suitable coil connected to function generator will generate
a magnetic field.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/

 

[GWBush]

On Wed, 18 May 2005 05:23:46 GMT, "Ban" <bansuri@web.de> wrote:

Robert Clark wrote:
snip childish BS
I remember being 13yrs. old and discussing things like this with my
roommates at public school. It is a nice exercise being kids, but a grown up
person should switch on the probability check before x-posting to all these
NGs.

You are assuming that these peopleare grown-up and mature to start.

 

[John C. Polasek]

On 14 May 2005 13:45:20 -0700, "Dave" <davidqanta@yahoo.com> wrote:

Suppose you have 220 volts AC and a load such as an
electric fan. Is the current before and after the
load exactly 100% similar in value? Are there loads
wherein the current can become different before and
after the load. If they are all 100% exactly the
same. How come the two parallel electric cord glued
together commonly used in appliances still has residue
magnetic field (like 1.5mG) and they don't cancel 100%.
They theoretically should since the current before and
after the load is exactly the same so the magnetic field
is exactly 180 degrees out of phase so 0 mG output should
suppose to occur.

Thanks.

Dave
Another way to think of it is as an inductor. Imagine a loop of wire

with X amperes flowing through the loop, and realize that the
inductance can be computed as well as flux which would be proportional
to the current and area enclosed.
Now flatten the loop so the two wires are separated by D and if you
still have an area enclosed, then you still have an inductance working
and you still have a single current flowing and there will be a
magnetic field present..
John Polasek
http://www.dualspace.net

 

[bz]

"Robert Clark" <rgregoryclark@yahoo.com> wrote in
news:1116422302.622609.79280@g47g2000cwa.googlegroups.com:

This page gives the resistance over 200 km for a 3 cm diameter cable
as only 7.9 ohms:

Electric Current.
"A high voltage transmission line has an aluminum cable of diameter
3.0cm, 200km long. What is the resistance of this cable? Solution:
The resistivity of aluminum is 2.8*10^(-8)ohm-m. the length of the
cable is 2*10^5m. The diameter of the cable is 3cm and its
cross-sectional area is equal to Pi*(d/2)^2 or 7.1*10^(-4) m^2.
Substituting these values into R = rL/A the resistance of the cable can
be determined.
R = (2.8*10^(-8)*2*10^5)/( 7.1*10^(-4)) = 7.9 ohms".
http://electron9.phys.utk.edu/phys136d/modules/m6/current.htm

For a wider cable the resistance will be less in proportion to the
cross-sectional area.

You are correct.

The discrepancy is in this figure: 2.8*10^(-8) ohm meter
Mathcad has 2.655 x 10^-6 ohm cm.

I used 2.655e-6 ohm meters!

I didn't look at the units closely enough.

I should have said 7.512 ohms for two 3 cm wires.


--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+sp@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[Luhan Monat]

John Larkin wrote:

We had a lot of them here. We called them estholes:

"Yes, I'm standing on your face, and I'm wearing cleats, but if you
really want to be miserable, it's your problem."

Some friends of mine who did EST long before I did, already used the
term 'estholes' themselves.

--
Luhan Monat: luhanis(at)yahoo(dot)com
http://members.cox.net/berniekm
"Any sufficiently advanced magick is
indistinguishable from technology."

 

[Eric Chomko]

Charles Jean (alchemcj@earthlink.net) wrote:
: On Tue, 17 May 2005 22:21:34 +0100, "George Dishman"
: <george@briar.demon.co.uk> wrote:

: >
: >"Robert Clark" <rgregoryclark@yahoo.com> wrote in message
: >news:1116359611.618267.84110@g47g2000cwa.googlegroups.com...
: >
: >> The question: how much power would be lost by
: >> sending it along a 100km long cable?
: >
: >Choose your voltage. Divide power P by voltage V to
: >get current I. Loss is I^2 * R. You need to work
: >out R using the resistivity of the material and the
: >length. Remember to count both wires.
: >
: >George
: >


: I assume you will be running two cables for the power, a hot and a
: return. How about insulation of the wires from each other? Is the
: conductor here the carbon fiber itself or some metal? Then calculate:
: a) the total mass of 100,000 ft. of the cables
: b) the electrical resistance of 100,000 ft. of the the conductors
: c) power loss through the conductors
: d) temperature rise through the conductors


: "There are known knowns. These are things that we know we know.
: There are known unknowns. That is to say, there are some
: things that we know we don't know. But there are also unknown
: unknowns. These are things we don't know we don't know."
: -Secretary of Defense Donald Rumsfeld


Makes me think of the little passage from the Koran I think:

He who knows not and knows he knows not is simple, teach him,
He who knows and knows not he knows is asleep, awaken him,
He who knows not and knows not he knows not is a fool, shun him,
He who knows and knows he knows is a leader, follow him.

Eric