There are LEDs out there that blinks by themself. I think you supply
them with 3V or 5V or something and it has all the electronics built
in them. They look like regular LEDs. Check with digikey or something.

Mounir



--- In Electronics_101@y..., Doug Hale <doughale@x> wrote:

Just the first four hits grom a google search of "LED Flasher"

Doug Hale

griffengm@y... wrote:

I'd like to build a flashing LED strobe for my recumbent bike.

Are

there any kits or How-To books I might use?
I would like to use several led's mounted on the flag whip with

power

source and as much components as possible on the frame.
Most of what I find are way too big and/or expensive.
I have minimal electronics experience but can follow directions

and

have built some kit radios and similar stuff.



To unsubscribe from this group, send an email to:
Electronics_101-unsubscribe@y...



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Sunantoro,

When you say "magnetic field" do you mean it the magnetic field in the
inductance issue?

As long as we are splitting hairs, [whop, one rabbit into two]
You can have a magnetic field in an inductor but not in inductance.
Inductance is a property that induces voltage in a conductor.
True it takes a mag. field but inductance doesn't directly take into account
of the quantity of mag field.

My aren't we contemplating navels tonight?

Jim

Sunantoro,

When people discuss about capacitor, they use "Charge" and "Energy"
interchangeably. This is rather confusing or ambiguous (to me).
Can we simply change it with "Electrons" which flow and accumulate in one
plate when the opposite plate becomes lack of it (electrons)?

Don't think any electrons accumulate on the plates. Where would they stay.
I'm thinking now that charge is the wrong term to use for the resulting
stored energy. We often say that a capacitor stores a charge, and it
certainly has to be charged, and the text books talk coulombs something
fierce when they get to capacitors. I still can't see the energy in a cap
as stored electrons, that's particles. And fields are not supposed to be
particles, or am I wrong there too.

By using this understanding, I believe there is no need to elaborate further
on "Charge" or "Energy",

Actually, I have a problem with the term energy to describe what is stored
too since energy includes time, i.e. watt seconds, joules. But the stored
energy is at rest. OR are we talking about the amount of joules it took
to charge... oops, to store the energy.

Jim

开云体育

d nixon,

Another interesting experiment would be to insert a metal plate inside the
dielectric so that you have: plate-dielectric-plate-dielectric-plate. The
middle plate (ground it?) should prevent any magnetic field from forming and
you may not be able to charge this capacitor at all.

Hmm... Where was the ground when this capacitor was charged. Did that
change. Too many loose ends to predict. My first reaction was that this
would be two series caps, which I think it is, grounding the center plate
threw the monkey wrench.

Jim

Mike,
When you say "magnetic field" do you mean it the magnetic field in the
inductance issue?
SUNAN

Neal,

'The energy in a capacitor is actually stored in the electric field within
the dielectric.' Sounds like it's stored in the dielectric. Now some
interpretation which I would be allowed if I were a student reading this

The problem is wording. The field goes _through_ the dialectric. It is not
_in_ the dialectric.

Sound like a split hair to me. How does the field get through the dielectric
without
being in it. If the dielectric is swapped after the original charging voltage is
removed,
will the field strength change? Of course the process messes things up, how do
you
swap dielectrics without upsetting things?

Jim

Sorry to have inadvertently click the "send" button when it should have been
the "save" button. Those two button are located side by side on my PC.

When people discuss about capacitor, they use "Charge" and "Energy"
interchangeably. This is rather confusing or ambiguous (to me).
Can we simply change it with "Electrons" which flow and accumulate in one
plate when the opposite plate becomes lack of it (electrons)?
By using this understanding, I believe there is no need to elaborate further
on "Charge" or "Energy", because electrical events are merely the flow of
electrons from substances with plenty of electrons to substances which are
lacking of it (electrons).

SUNAN

"J. Pinkston",

I don't understand it either but the Navy training manuals agree with Jim. I
think I'm going to try an experiment when I get time. I'll make a capacitor
out of two flat plates with a piece of paper between them. After charging
them, I'll change paper & see if they discharge. I'll get right to that &
report the results....after I paint the house, remodel the kitchen, put new
carpet in the hall.....etc.,etc. The honeydews are pretty thick right now.

Here's my prediction of what will happen, although you may not be able to
detect this. When the paper is between the plates there will be a charge of
so many coulombs. When you remove the paper, the charge will fall to
match the new dielectric. Now whether that would happen whether or
not the charging voltage is removed or not, I won't try to predict.
I guess the question is whether the electric field will changer after the
charging voltage is removed AND the dielectric constant is changed.

Jim

Doug,

The charge IS in the plates, the field IS in the dielectric.

Cook seemed to fall short of saying that. First off, the charge
he referred to was not the resulting stored energy but that
what produced the storage in the first place.

The charge and the field ARE NOT the same thing.

An electric field exists between two opposite charges.

OK, I see that. Now, does the potential at the capacitor terminals
constitute the charge. I guess it does, I think I have always thought
of the charge as all those stored electrons. Where do they live, or
do they live at all? Maybe the charge doesn't consist of misplaced
electrons but the field. Countless years of oversimplification of a
concept. But as I said, it didn't undermine my ability to use capacitors.
Not any more than using conventional current or electron flow.

Jim

Rama,

?Charge is stored on the plates and the energy in the gap between the plates.

No that was not my point, correct or not I was saying that the energy is stored in the e.s. field not on the plates or in the dielectric. Just energy stored in an inductor is stored in the mag. field.

This energy results from the field between the positive and negative charges on the plates.

Yes, the parameters of the field are determined by the size of the plates, their distnce apart, i.e. the thickness of the dielectric and the dielectric constant.

The dielectric helps in keeping the charge apart.

I think it would be misleading to say that, in one sense it's true but that's not it's purpose.?

The maximum amount of charge that can be kept apart depends on the dielectric.

Now that language is becomming more grotesque and losing meaning, I don't about keeping charge apart. .

In case the amount exceeds this level, then the dielectric breaks down

Your mixing dielecric constant with dielectric strength.

and the capacitor gets discharged real fast.

Are you talking leakage due to exceeding dielecric strength?

The dielectric also helps in???? chanellising

What does that word meain? If you had plates that had less area than the dielectric, I think the dielectric that was 'sticking out' would be as it it weren't there. Like lunch meat that sticks out of the sandwich. :-)

the field between the plates - this results in different capacitances for different dielectrics if the area of the plates and the distance between them remains the same.

Yes, I think that the distance between the plates is more important than dielectric thickness. If the plates were farther apart than the dielectric thickness you'd have a mixture of dielectrics, the normal dielectric plus some air (or vacuum.)

Jim

Another interesting experiment would be to insert a metal plate inside the dielectric so that you have: plate-dielectric-plate-dielectric-plate. The middle plate (ground it?) should prevent any magnetic field from forming and you may not be able to charge this capacitor at all.

-Mike

From: "J. Pinkston" <pinkston@...>
Reply-To: Electronics_101@...
To: <Electronics_101@...>
Subject: Re: [Electronics_101] Digest Number 140
Date: Mon, 29 Oct 2001 20:39:26 -0600

________________________________________________________________________

Message: 24
Date: Mon, 29 Oct 2001 19:34:55 -0000
From: "Mr." <rschechter@...>
Subject: Re: Digest Number 134

--- In Electronics_101@y..., Jim Purcell <jpurcell@w...> wrote:.

Sorry, but the charge is stored in the dielectric. That's why the

amount of

capacitance depends in part on the kind of dielectric. A conductor

will not

store a charge, only provide a path for it. Insulators respond to

the potential


Jim, My understanding of the capacitor is that the actual electron
are stored on the plate, or conductor. The closer you can get them
together (meaning a thinner and less conductive dielectric), the more
force they exert on each other. Both parts are involved, but the
charge is on the plates.
Rex

I don't understand it either but the Navy training manuals agree with Jim. I
think I'm going to try an experiment when I get time. I'll make a capacitor
out of two flat plates with a piece of paper between them. After charging
them, I'll change paper & see if they discharge. I'll get right to that &
report the results....after I paint the house, remodel the kitchen, put new
carpet in the hall.....etc.,etc. The honeydews are pretty thick right now.
:)

Jim KC0GSX

_________________________________________________________________
Get your FREE download of MSN Explorer at

Ah, so it's the field that stores all the energy? And fields, like any EM radiation, don't need a medium.

When the field collapses the energy is transmitted to the plates, which goes through the wires...

Hmmm.

-Mike

From: "G Ramasubramani" <grama@...>
Reply-To: Electronics_101@...
To: <Electronics_101@...>
Subject: Re: [Electronics_101] The need to know!
Date: Mon, 29 Oct 2001 18:12:39 -0800

Jim,

Liked your mail. Charge is stored on the plates and the energy in the gap between the plates. This energy results from the field between the positive and negative charges on the plates. The dielectric helps in keeping the charge apart. The maximum amount of charge that can be kept apart depends on the dielectric. In case the amount exceeds this level, then the dielectric breaks down and the capacitor gets discharged real fast. The dielectric also helps in chanellising the field between the plates - this results in different capacitances for different dielectrics if the area of the plates and the distance between them remains the same.

Rama
----- Original Message -----
From: Jim Purcell
To: Electronics_101@...
Sent: Monday, October 29, 2001 4:51 PM
Subject: [Electronics_101] The need to know!


Why is as important as What. When If I know a collection of facts but do not
understand why they are so, I have no principles that I can apply in order to
apprehend other facts. So when struggling to understand something I may
appear to be arguing, as in stating that the other person is wrong. While I
have been known to do that some times, usually what I'm doing is trying to
get my mind around the facts.

That I never took college level physics may explain my difficulties, then
again maybe not since I don't know to what extent the issue of 'where a
charge is stored in a capacitor, might be answered by college level physics,
at least as much of it as an EE might take. As a technician I have often had
to just accept some premise, not having the knowledge to question them or to
verify them for that matter. And being pragmatic I see no problem with that
as long is it doesn't interfere with what I may be trying to do. For
example, who care which convention is used, current of electron flow as long
as we can follow the function of a circuit. Likewise knowing whether a
capacitors charge is stored, the plates or the dielectric won't help me
understand why the capacitor seems to allow current to flow right through it.
In fact I can operate as current does flow though the capacitor and when
working with them in actual circuits we assume a capacitor to be an AC short
circuit, albeit a frequency sensitive one.

All of this leads me to quote from Nigel Cook, DC-AC Second Edition, 1993.
In chapter 11, under the summary on capacitance he actually states that the
'charges on the plates produce an electric field...' Sound like he's saying
that the charge is stored on the plates. The last sentence in the paragraph
states...
'The energy in a capacitor is actually stored in the electric field within
the dielectric.' Sounds like it's stored in the dielectric. Now some
interpretation which I would be allowed if I were a student reading this
book, but which could be mistaken. Nothing new, I've been wrong before and I
plan to be wrong again before I go to that great capacitor in the sky to be
fully charged for eternity. :-)
I think both views may be wrong. The energy is stored in the electrostatic
field, not on the plates, not in the dielectric. That certainly would explain
why vacuum capacitors can work. It also agrees with my notion that a
conductor can't really store a charge. Oh, and this also agrees with the
idea that energy is stored in the magnetic field in an inductor, which always
seemed strange to me.

Am I right, is one of the other view right? I really don't give a poop. But I
have an explanation that will satisfy me until someone comes up with a better
one. And I feel that I understand capacitors better now. Maybe I'll take one
out to dinner some time.

Jim


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_________________________________________________________________
Get your FREE download of MSN Explorer at

The key is the special signals that are recorded on cd.

No, the key is how much money some fool is willing to pay for such a device. Package it with a new diet and you've got yourself a money-maker.

-Mike

From: "James" <xenoticus@...>
Reply-To: Electronics_101@...
To: Electronics_101@...
Subject: [Electronics_101] Some very interesting links for you
Date: Mon, 29 Oct 2001 21:33:35 -0000

Hello,
My name is James Roberts and I am primarily associated with the
mind-l yahoo group. I have some interesting links for you.

The first concerns a public safety study of a mind-altering device
comprised of a helmet fitted with electromagnets. It can produce
interesting experiences and positive emotional change. The key is the
special signals that are recorded on cd.



The second concerns an arrangement of high-voltage equipment that
produces levitation in magnetic and non-magnetic objects, spontaneous
fires, floating lights, etc.



Sic Luceat Lux,
Xenoticus

_________________________________________________________________
Get your FREE download of MSN Explorer at

Just the first four hits grom a google search of "LED Flasher"

Doug Hale

griffengm@... wrote:

Some snippage and comments below:

________________________________________________________________________

Message: 24
Date: Mon, 29 Oct 2001 19:34:55 -0000
From: "Mr." <rschechter@...>
Subject: Re: Digest Number 134

--- In Electronics_101@y..., Jim Purcell <jpurcell@w...> wrote:.

Sorry, but the charge is stored in the dielectric. That's why the

amount of

capacitance depends in part on the kind of dielectric. A conductor

will not

store a charge, only provide a path for it. Insulators respond to

the potential


Jim, My understanding of the capacitor is that the actual electron
are stored on the plate, or conductor. The closer you can get them
together (meaning a thinner and less conductive dielectric), the more
force they exert on each other. Both parts are involved, but the
charge is on the plates.
Rex

I don't understand it either but the Navy training manuals agree with Jim. I
think I'm going to try an experiment when I get time. I'll make a capacitor
out of two flat plates with a piece of paper between them. After charging
them, I'll change paper & see if they discharge. I'll get right to that &
report the results....after I paint the house, remodel the kitchen, put new
carpet in the hall.....etc.,etc. The honeydews are pretty thick right now.
:)

Jim KC0GSX

Jim Purcell wrote:
>Why is as important as What. When If I know a collection of
facts but do not
>understand why they are so, I have no principles that I can
apply in order to
>apprehend other facts. So when struggling to understand
something I may
>appear to be arguing, as in stating that the other person
is wrong. While I
>have been known to do that some times, usually what I'm
doing is trying to
>get my mind around the facts.
>
>That I never took college level physics may explain my
difficulties, then
>again maybe not since I don't know to what extent the issue
of 'where a
>charge is stored in a capacitor, might be answered by
college level physics,
>at least as much of it as an EE might take. As a technician
I have often had
>to just accept some premise, not having the knowledge to
question them or to
>verify them for that matter. And being pragmatic I see no
problem with that
>as long is it doesn't interfere with what I may be trying
to do. For
>example, who care which convention is used, current of
electron flow as long
>as we can follow the function of a circuit. Likewise
knowing whether a
>capacitors charge is stored, the plates or the dielectric
won't help me
>understand why the capacitor seems to allow current to flow
right through it.
>In fact I can operate as current does flow though the
capacitor and when
>working with them in actual circuits we assume a capacitor
to be an AC short
>circuit, albeit a frequency sensitive one.
>
>All of this leads me to quote from Nigel Cook, DC-AC Second
Edition, 1993.
>In chapter 11, under the summary on capacitance he actually
states that the
>'charges on the plates produce an electric field...' Sound
like he's saying
>that the charge is stored on the plates. The last sentence
in the paragraph
>states...
>'The energy in a capacitor is actually stored in the
electric field within
>the dielectric.' Sounds like it's stored in the dielectric.
Now some
>interpretation which I would be allowed if I were a student
reading this
>book, but which could be mistaken. Nothing new, I've been
wrong before and I
>plan to be wrong again before I go to that great capacitor
in the sky to be
>fully charged for eternity. :-)
>I think both views may be wrong. The energy is stored in
the electrostatic
>field, not on the plates, not in the dielectric. That
certainly would explain
>why vacuum capacitors can work. It also agrees with my
notion that a
>conductor can't really store a charge. Oh, and this also
agrees with the
>idea that energy is stored in the magnetic field in an
inductor, which always
>seemed strange to me.
>
>Am I right, is one of the other view right? I really don't
give a poop. But I
>have an explanation that will satisfy me until someone
comes up with a better
>one. And I feel that I understand capacitors better now.
Maybe I'll take one
>out to dinner some time.
>
>Jim
>

I have designed with both but have never done the replacement.

I shouldn't be hard - they work the same way.

Doug

Budijanto S wrote:

I'd like to build a flashing LED strobe for my recumbent bike. Are
there any kits or How-To books I might use?
I would like to use several led's mounted on the flag whip with power
source and as much components as possible on the frame.
Most of what I find are way too big and/or expensive.
I have minimal electronics experience but can follow directions and
have built some kit radios and similar stuff.