magnetic field

[CWatters]

"operator jay" <none@none.none> wrote in message
news:668re.4007$mN.42921@news1.mts.net...

"John Fields" <jfields@austininstruments.com> wrote in message
news:56cpa1d2l1ikr3moduf0r2vgo7elionbls@4ax.com...
On 12 Jun 2005 05:50:43 -0700, "LJ" <little-joe@usa.net> wrote:

OK! So I see now that the "75-300" foot range is the "range of the
range" if I understand correctly? I was thinking that the unit could be
set for a specific distance 'within' THAT range... DUH! Am I on the
right track here?

---
Yes. Unfortunately, since the thing isn't a transponder and is merely
an RF transmitter sending an RF carrier (perhaps modulated)

Must be modulated, right? Otehrwise, someone would set up a little
oscillator and be free to come and go?

and presumably numbered in case two people living next to each other get
tagged.

 

[CWatters]

"Tristan Beeline" <mist_distance@hotmail.com> wrote in message
news:55f4364e.0506121952.526f39d7@posting.google.com...

I need to create a force field to trap a neutron star.

What do I need to create such a force field and where can I buy the parts
???

Try alt.startrek.cardassian

 

[Impmon]

On 12 Jun 2005 20:52:11 -0700, mist_distance@hotmail.com (Tristan
Beeline) wrote:

I need to create a force field to trap a neutron star.

What do I need to create such a force field and where can I buy the parts ???

First you need to get around NRC (or whatever nuclear police you have
in your country) and build a portable nuclear reactor capable of
generating several hundred terawatts. At this time no one's ever
created one with that kind of output and still be portable.
--
When you hear the toilet flush, and hear the words "uh oh", it's already
too late. - by anonymous Mother in Austin, TX
To reply, replace digi.mon with phreaker.net

 

[John Fields]

On Sun, 12 Jun 2005 23:10:45 -0500, "operator jay" <none@none.none>
wrote:

"John Fields" <jfields@austininstruments.com> wrote in message
news:56cpa1d2l1ikr3moduf0r2vgo7elionbls@4ax.com...
On 12 Jun 2005 05:50:43 -0700, "LJ" <little-joe@usa.net> wrote:

OK! So I see now that the "75-300" foot range is the "range of the
range" if I understand correctly? I was thinking that the unit could be
set for a specific distance 'within' THAT range... DUH! Am I on the
right track here?

---
Yes. Unfortunately, since the thing isn't a transponder and is merely
an RF transmitter sending an RF carrier (perhaps modulated)

Must be modulated, right? Otehrwise, someone would set up a little
oscillator and be free to come and go?

---
Seems likely.

--
John Fields
Professional Circuit Designer

 

[James T. White]

"Impmon" <impmon@digi.mon> wrote in message
news:25gqa1peg6p8488f4fmf2gipqqapojul83@4ax.com...

On 12 Jun 2005 20:52:11 -0700, mist_distance@hotmail.com (Tristan
Beeline) wrote:

Snip
First you need to get around NRC (or whatever nuclear police you have
in your country) and build a portable nuclear reactor capable of
generating several hundred terawatts. At this time no one's ever
created one with that kind of output and still be portable.

Or stationary for that matter.......

--
James T. White

 

[Dave Garnett]

"Robert" <geronnimo@vp.pl> wrote in message
news:30a944c0.0506132327.29a22481@posting.google.com...

Hi,
I have LPT (ISP AVR) programmer, (
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=50915&item=7523475186&rd=1&ssPageName=WDVW
)
what happens when the programmer disconnect from PCB (with ATmega8)
during programming time. (programming with fuse bits) ?
Can I destroy my Atmega ?

I have had a case where the SPIEN fuse got set somehow by disconnecting
during programming. This means that the ATmega8 can only be (re)programmed
in Parallel (High Voltage) mode. If you don't have such a programmer to
hand, it is probably simpler and cheaper to throw the chip away ...

Dave




Posted Via Nuthinbutnews.Com Premium Usenet Newsgroup Services
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[Mike Harrison]

On Tue, 14 Jun 2005 08:46:14 +0100, "Dave Garnett" <dave.garnett@metapurple.co.uk> wrote:

"Robert" <geronnimo@vp.pl> wrote in message
news:30a944c0.0506132327.29a22481@posting.google.com...
Hi,
I have LPT (ISP AVR) programmer, (
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=50915&item=7523475186&rd=1&ssPageName=WDVW
)
what happens when the programmer disconnect from PCB (with ATmega8)
during programming time. (programming with fuse bits) ?
Can I destroy my Atmega ?

I have had a case where the SPIEN fuse got set somehow by disconnecting
during programming. This means that the ATmega8 can only be (re)programmed
in Parallel (High Voltage) mode. If you don't have such a programmer to
hand, it is probably simpler and cheaper to throw the chip away ...

Dave

Another way that Atmels can appear to die through mis-programming is if the oscillator type gets
set to something incompatible with the on-board connections, in particular, if the application uses
the internal oscillator, and the fuses get set to an external oscillator type, then further
programming is not possible.
Fortunately this situation can easily be recovered by applying an extarnal clock source to the OSC
In pin while reprogramming the oscillator fuses.

 

[fuentesmartinez]

Bombi,

would you share your datasheet for the QEDS-9500 with me?

i got the datasheet for the HEDS-5500 but something is wrong,
i have not been able to make it work... of course it could be damaged
but i would like to see the datasheet first...

thanks in advance

juan

 

[Dave]

"qude" <qmdynamics@yahoo.com> wrote in message
news:1119070735.052785.12830@g14g2000cwa.googlegroups.com...

Suppose you have voltage = 110 volts and current 2 Ampere

From P = V I

Power = 220 Watts

Suppose you have voltage = 12 volts and current 18.3 Ampere

Power = 220 Watts

What is the behavior of the load in each case? They both
have the same 220 watts power yet the second one with a
18.3 Ampere current should be affected more.. yet if the
voltage in the first is 110 volts.. the power is
similar...

What is the behavior of loads with more voltage or
more current. Which can it take more. What part is
affected more, etc.

Pls. elaborate (also the physics part of it). Many thanks.

Qude

no answer possible from what you are asking as your terms are not defined.

what do you mean 'affected more'?? what type of 'behavior' are you thinking
of?

 

[Dave]

"qude" <qmdynamics@yahoo.com> wrote in message
news:1119130892.503951.118600@g49g2000cwa.googlegroups.com...

Dave wrote:
"qude" <qmdynamics@yahoo.com> wrote in message
news:1119070735.052785.12830@g14g2000cwa.googlegroups.com...

Suppose you have voltage = 110 volts and current 2 Ampere

From P = V I

Power = 220 Watts

Suppose you have voltage = 12 volts and current 18.3 Ampere

Power = 220 Watts

What is the behavior of the load in each case? They both
have the same 220 watts power yet the second one with a
18.3 Ampere current should be affected more.. yet if the
voltage in the first is 110 volts.. the power is
similar...

What is the behavior of loads with more voltage or
more current. Which can it take more. What part is
affected more, etc.

Pls. elaborate (also the physics part of it). Many thanks.

Qude

no answer possible from what you are asking as your terms are not
defined.
what do you mean 'affected more'?? what type of 'behavior' are you
thinking
of?

For example, what creates brighter light bulbs. A 110V/2Ampere
bulb or a 12 Volts/18.3Ampere bulb, both produce 220 watts of power.
what's the occasion when you must choose the 110V/2A or 12V/18.3A
in designing loads.

qude

you pick the voltage based on other considerations... usually by what is
available for whatever you are designing. i.e. if you are designing for a
house or office you use 110v, if you are designing for a car you use 12v.
or from what the load you have to power needs. i.e. if the load is designed
for 110v you give it 110v, if its designed for 12v you give it 12v. from
that you calculate current needed and how big of a wire you need for it.

 

[operator jay]

"qude" <qmdynamics@yahoo.com> wrote in message
news:1119130892.503951.118600@g49g2000cwa.googlegroups.com...

Dave wrote:
"qude" <qmdynamics@yahoo.com> wrote in message
news:1119070735.052785.12830@g14g2000cwa.googlegroups.com...

Suppose you have voltage = 110 volts and current 2 Ampere

From P = V I

Power = 220 Watts

Suppose you have voltage = 12 volts and current 18.3 Ampere

Power = 220 Watts

What is the behavior of the load in each case? They both
have the same 220 watts power yet the second one with a
18.3 Ampere current should be affected more.. yet if the
voltage in the first is 110 volts.. the power is
similar...

What is the behavior of loads with more voltage or
more current. Which can it take more. What part is
affected more, etc.

Pls. elaborate (also the physics part of it). Many thanks.

Qude

no answer possible from what you are asking as your terms are not
defined.
what do you mean 'affected more'?? what type of 'behavior' are you
thinking
of?

For example, what creates brighter light bulbs. A 110V/2Ampere
bulb or a 12 Volts/18.3Ampere bulb, both produce 220 watts of power.
what's the occasion when you must choose the 110V/2A or 12V/18.3A
in designing loads.

qude

You design it based upon what voltage the user will have available. If you
manufacture an amplifier for use in homes in North America, and design it so
it will work off of +-31Vdc, you're gonna have trouble selling it and anyone
who buys it will have trouble using it. If you make it so it works off of
120Vac or thereabouts that's a great idea. If you make an amplifier for use
in cars in North America, then you would probably design it to work off of
12Vdc or thereabouts.

If there is some situation whereby there is no voltage constraint like that,
then typically a moderate voltage and moderate current work well. High
voltages require lots of insulation. High currents require heavy conductors
and lose a lot of power to parasitic resistance.

j

 

[sue jahn]

"Dave" <noone@nowhere.com> wrote in message newsLudnRXQqPZ9nCnfRVn-ow@crocker.com...

"qude" <qmdynamics@yahoo.com> wrote in message
news:1119070735.052785.12830@g14g2000cwa.googlegroups.com...

Suppose you have voltage = 110 volts and current 2 Ampere

From P = V I

Power = 220 Watts

Suppose you have voltage = 12 volts and current 18.3 Ampere

Power = 220 Watts

What is the behavior of the load in each case? They both
have the same 220 watts power yet the second one with a
18.3 Ampere current should be affected more.. yet if the
voltage in the first is 110 volts.. the power is
similar...

What is the behavior of loads with more voltage or
more current. Which can it take more. What part is
affected more, etc.

Pls. elaborate (also the physics part of it). Many thanks.

Qude

no answer possible from what you are asking as your terms are not defined.
what do you mean 'affected more'?? what type of 'behavior' are you thinking
of?

I am so bad at maths I'll let you do
P = I^2 R
and see the resistance must be much lower for the 12 volt load
to consume the same power.

That also means a conductor like nichrome or tungsten will be fatter and
shorter than the 110 volt load. This can be a real mechanical advantage
for hot envelope halogen lamps because a long thin coil of wire can flop
around, shedding, fatiguing or actually striking the envelope.

This is why you don't see this type of lamp below ~100 watts in the
110 volt variety. Above ~300 watts the filiment can be short an
fat so doesn't require too much mechanical support.

That isn't quite what we call physics and I am guessing... lamps.

Sue...

 

[operator jay]

"qude" <qmdynamics@yahoo.com> wrote in message
news:1119133780.543387.272110@g14g2000cwa.googlegroups.com...

operator jay wrote:
"qude" <qmdynamics@yahoo.com> wrote in message
news:1119130892.503951.118600@g49g2000cwa.googlegroups.com...


Dave wrote:
"qude" <qmdynamics@yahoo.com> wrote in message
news:1119070735.052785.12830@g14g2000cwa.googlegroups.com...

Suppose you have voltage = 110 volts and current 2 Ampere

From P = V I

Power = 220 Watts

Suppose you have voltage = 12 volts and current 18.3 Ampere

Power = 220 Watts

What is the behavior of the load in each case? They both
have the same 220 watts power yet the second one with a
18.3 Ampere current should be affected more.. yet if the
voltage in the first is 110 volts.. the power is
similar...

What is the behavior of loads with more voltage or
more current. Which can it take more. What part is
affected more, etc.

Pls. elaborate (also the physics part of it). Many thanks.

Qude

no answer possible from what you are asking as your terms are not
defined.
what do you mean 'affected more'?? what type of 'behavior' are you
thinking
of?

For example, what creates brighter light bulbs. A 110V/2Ampere
bulb or a 12 Volts/18.3Ampere bulb, both produce 220 watts of power.
what's the occasion when you must choose the 110V/2A or 12V/18.3A
in designing loads.

qude


You design it based upon what voltage the user will have available. If
you
manufacture an amplifier for use in homes in North America, and design
it so
it will work off of +-31Vdc, you're gonna have trouble selling it and
anyone
who buys it will have trouble using it. If you make it so it works off
of
120Vac or thereabouts that's a great idea. If you make an amplifier for
use
in cars in North America, then you would probably design it to work off
of
12Vdc or thereabouts.

If there is some situation whereby there is no voltage constraint like
that,
then typically a moderate voltage and moderate current work well. High
voltages require lots of insulation. High currents require heavy
conductors
and lose a lot of power to parasitic resistance.

j


I'm just interested in the theoretical side of it.

Suppose my source can equally do a 220v/2A and 12V/18A. If I
get a light bulb for each. What would be brighter.

Well, the bulbs will be different to suit the voltage and current to be
applied. These construction and materials differences would determine
brightness and other light characteristics more than the voltage and current
per se. In either case the voltage and current deliver energy at the same
rate to the filament.

Or better yet. I'm interested in the physics side of what's
going on inside the wires. In the 12V/18A. More electrons
flow in the wire.. however the voltage is only 12V. In
the case of the 220v/2A. Less electrons flow in the wire. So
what is the function of the voltage or potential difference.
In the 220v/2A case. There are fewer electrons but bigger
potential difference. What is the effect of it on electron
flow compare to the larger 18A but lower voltage or potential
difference. Since electron flow has same speed in all ampere
rating. What is the function of the voltage in the behavior
of the current?

Hmmm. I think the electron flow does not have the same speed in all ampere
ratings. I would think that

I = v * A * p

I current (C/s, or A)
v drift velocity of electrons (m/s)
A cross sectional area of conductor (m^2)
p density of free electrons in the material that the wire is made of (C/m^3,
or # free electrons/m^3 * 1.6E-19)

A and p would basically be fixed for a certain conductor. So drift velocity
should vary with current. Though I may be proven wrong. Thinking about
Ohm's law, this all seems to work out nicely, in my head.

Are you familiar with the difference between (a) the speed of light in a
conductor (on the order of 2*10^8m/s), (b) the instantaneous speed of an
electron as it pinballs its way down a conductor (on the order of 10^6m/s),
and (c) the "drift velocity" or overall average speed with which an electron
makes its way down a conductor (I'll say 10^-4m/s to give a feel of the
magnitude but I think it would vary hugely)?

j

 

[Don Kelly]

"qude" <qmdynamics@yahoo.com> wrote in message
news:1119133780.543387.272110@g14g2000cwa.googlegroups.com...

operator jay wrote:
"qude" <qmdynamics@yahoo.com> wrote in message
news:1119130892.503951.118600@g49g2000cwa.googlegroups.com...


Dave wrote:
"qude" <qmdynamics@yahoo.com> wrote in message
news:1119070735.052785.12830@g14g2000cwa.googlegroups.com...

Suppose you have voltage = 110 volts and current 2 Ampere

From P = V I

Power = 220 Watts

Suppose you have voltage = 12 volts and current 18.3 Ampere

Power = 220 Watts

What is the behavior of the load in each case? They both
have the same 220 watts power yet the second one with a
18.3 Ampere current should be affected more.. yet if the
voltage in the first is 110 volts.. the power is
similar...

What is the behavior of loads with more voltage or
more current. Which can it take more. What part is
affected more, etc.

Pls. elaborate (also the physics part of it). Many thanks.

Qude

no answer possible from what you are asking as your terms are not
defined.
what do you mean 'affected more'?? what type of 'behavior' are you
thinking
of?

For example, what creates brighter light bulbs. A 110V/2Ampere
bulb or a 12 Volts/18.3Ampere bulb, both produce 220 watts of power.
what's the occasion when you must choose the 110V/2A or 12V/18.3A
in designing loads.

qude


You design it based upon what voltage the user will have available. If
you
manufacture an amplifier for use in homes in North America, and design
it so
it will work off of +-31Vdc, you're gonna have trouble selling it and
anyone
who buys it will have trouble using it. If you make it so it works off
of
120Vac or thereabouts that's a great idea. If you make an amplifier for
use
in cars in North America, then you would probably design it to work off
of
12Vdc or thereabouts.

If there is some situation whereby there is no voltage constraint like
that,
then typically a moderate voltage and moderate current work well. High
voltages require lots of insulation. High currents require heavy
conductors
and lose a lot of power to parasitic resistance.

j


I'm just interested in the theoretical side of it.

Suppose my source can equally do a 220v/2A and 12V/18A. If I
get a light bulb for each. What would be brighter.

Or better yet. I'm interested in the physics side of what's
going on inside the wires. In the 12V/18A. More electrons
flow in the wire.. however the voltage is only 12V. In
the case of the 220v/2A. Less electrons flow in the wire. So
what is the function of the voltage or potential difference.
In the 220v/2A case. There are fewer electrons but bigger
potential difference. What is the effect of it on electron
flow compare to the larger 18A but lower voltage or potential
difference. Since electron flow has same speed in all ampere
rating. What is the function of the voltage in the behavior
of the current?

qude

Don't get wound up in electron flow. The individual electrons just drift

along and, in case of AC, wobble around a bit.

Note that power depends on both current and voltage, not just current alone.
The theoretical answer is that both the 12V/18A and the 220V/2A lamps the
power and the brightness is the same assuming the same filament temperature
(-which depends also on non-electrical factors). What appears to be more
electrons passing a given point at 18A than at 2A really does not determine
this.

The voltage is the driving force behind the current-Your 12V lamp has a
resistance of 12/18 ohms while the 220V lamp has a resistance of 220/2 ohms.
If you applied 220V to your 12V lamp- it would be extremely bright
momentarily just before it blew up as the current would be 330A.

For any application there is an optimal voltage range. For automobiles 12V
was it but more recently moving to 48V has been considered because of
higher electrical loads. For homes, 12V is impractical and 120/240V is
better. For power distribution, this is too low, etc.
--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

 

[R. Steve Walz]

qude wrote:

Suppose you have voltage = 110 volts and current 2 Ampere

From P = V I

Power = 220 Watts

Suppose you have voltage = 12 volts and current 18.3 Ampere

Power = 220 Watts

What is the behavior of the load in each case?
------------------------

There isn't one same load.
They are two different loads, their resistances differ wildly.

R = V/I

Pls. elaborate (also the physics part of it). Many thanks.

Qude

-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

 

[me]

Or better yet. I'm interested in the physics side of what's
going on inside the wires. In the 12V/18A. More electrons
flow in the wire.. however the voltage is only 12V. In
the case of the 220v/2A. Less electrons flow in the wire. So
what is the function of the voltage or potential difference.
In the 220v/2A case. There are fewer electrons but bigger
potential difference. What is the effect of it on electron
flow compare to the larger 18A but lower voltage or potential
difference. Since electron flow has same speed in all ampere
rating. What is the function of the voltage in the behavior
of the current?

qude

E=IR or I=E/R

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
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[CWatters]

"qude" <qmdynamics@yahoo.com> wrote in message
news:1119070735.052785.12830@g14g2000cwa.googlegroups.com...

Suppose you have voltage = 110 volts and current 2 Ampere

From P = V I

Power = 220 Watts

Suppose you have voltage = 12 volts and current 18.3 Ampere

Power = 220 Watts

What is the behavior of the load in each case? They both
have the same 220 watts power yet the second one with a
18.3 Ampere current should be affected more.. yet if the
voltage in the first is 110 volts.. the power is
similar...

What is the behavior of loads with more voltage or
more current. Which can it take more. What part is
affected more, etc.

The effective resistance of each load is different for the two cases you
describe...

1) 110/2 = 55 Ohms
2) 12/18.3 = 0.66 Ohms

If these were light bulbs the wire filament needed to make the 12V lamp
(0.66 Ohms) would be much thicker than the 110V lamp (55 Ohms). Therefore
the 12V lamp would be more robust and resistant to the thermal shock that
occurs when it's switched on/off. Indeed low voltage Halogen downlight bulbs
do last longer than mains voltage lamps.

 

[Joe Soap]

In response to what qude <qmdynamics@yahoo.com> posted in
news:1119172222.190468.82400@f14g2000cwb.googlegroups.com:

Thanks for the answers but I want understand the physics side.

When 18A is said to flow into a wire. What is the difference of it in
terms of electron flow compared to lets say 2A.
It is 9 times greater. But current doesn't flow 'into' a wire, it flows

THROUGH it.

What does the voltage do to the current. It drives them you will say.
But how come you can drive a 18A current with only 12 volts whereas in
a 110 volts, the current is only 2A.
A guy called Ohm explained this ages ago. I = V/R. Current is

proportional to voltage, and inversely proportional to resistance.

It may have to do with the load. So in loads with lower resistance.
More electrons can pass thru it, right. In the case of the 18A/12
volts supply, more electrons pass thru the load. In the case of the
2A/110 volts. Only few electrons pass thru it.
Yes.

Now here's the problem.

That means using higher voltage didn't mean pushing greater amount of
electrons. So what is the function of voltage and current in terms of
electron movement?? Let's focus on the physics side of it.
Voltage difference - otherwise known as EMF (electromotive force) is the

force that drives the electrons, resistance opposes that movemnt. So more
emf, or less resistance, both mean more current flow.

-- Joe Soap. JUNK is stuff that you keep for 20 years, then throw away a
week before you need it.

 

[sue jahn]

"qude" <qmdynamics@yahoo.com> wrote in message news:1119172222.190468.82400@f14g2000cwb.googlegroups.com...

Thanks for the answers but I want understand the physics side.

When 18A is said to flow into a wire. What is the difference of it in
terms of
electron flow compared to lets say 2A.

What does the voltage do to the current. It drives them you will say.
But
how come you can drive a 18A current with only 12 volts whereas in a
110
volts, the current is only 2A.

It may have to do with the load. So in loads with lower resistance.
More
electrons can pass thru it, right. In the case of the 18A/12 volts
supply,
more electrons pass thru the load. In the case of the 2A/110 volts.
Only
few electrons pass thru it.

Now here's the problem.

That means using higher voltage didn't mean pushing greater amount of
electrons. So what is the function of voltage and current in terms of
electron movement?? Let's focus on the physics side of it.

qude

Clicking around these pages should get it on your own terms:

<< A "flow" defined as the rate of a quantity passing a given
point per unit time. When used without qualification, "current"
generally refers to electric current, which is given by:
http://scienceworld.wolfram.com/physics/Current.html

where is the resistivity. For a body of length L, resistance R,
and cross sectional area A, the electrical conductivity is given by

http://scienceworld.wolfram.com/physics/ElectricalConductivity.html

Sue...