Toshiba TV29C90 problem; Image fades to black...

[Kitchen Man]

On Sun, 12 Jun 2005 22:59:18 -0500, "operator jay" <none@none.none>
wrote:

You are the one with the requirements, assertions, and definitions, not me.

Actually, the ones with the requirements, assertions, and definitions
are codes and organizations such as the NEC and the IEEE, and the
bothersome universities that teach the stuff.

On this point:

Picture my flashlight, battery powered. Generally this is considered a dc
circuit. When I turn it on or off, there is 'change'. So is it in fact an
AC flashlight? If the battery starts to die there is a change so is it in
fact an AC battery? Etcetera. (These questions are rhetorical by the way).
I know better than to try to pin a strict name on these things where there
is not an (adequately) universal and strict definition.

You are talking about transients, and if you intend for the questions
to be rhetorical, then I think you should demonstrate some expertise
in the subject matter that shows why the questions' answers must be
obvious. I don't think they are, so I will answer the questions:

The behavior of the flashlight in your example is neither AC nor DC,
it is transient. The first case is the instantaneous step function
caused by the closing of a source to a circuit. The second case is a
long-term curved ramp caused by the decay of a voltage source. AC and
DC analyses are steady-state. AC analysis will never apply to the
example. DC analysis must be performed prior to the transient
analysis in order to provide a steady state model for the application
of time-sensitive mathematics.

There is quite a bit of information available on the web about circuit
analysis. Your curiosity is to be commended; you might consider a web
crawling adventure, or even an education in the field.

And hey operator jay, what do you operate? Not electrical
substations, I wouldn't guess.

--
Al Brennan

"If you only knew the magnificence of the 3, 6 and 9,
then you would have a key to the universe." Nicola Tesla

 

[--]

"Floyd L. Davidson" <floyd@barrow.com> wrote in message
news:87vf4jvxi2.fld@barrow.com...

John Fields <jfields@austininstruments.com> wrote:
On Sun, 12 Jun 2005 17:15:06 -0700, Don Lancaster <don@tinaja.com
wrote:

Sum a 1 volt peak sinewave with a 0.6 volt dc term and you have a
waveform whose polarity continuously changes but whose average value is
continuous.

---
No, you have a waveform with a polarity which changes _periodically_,
making it an AC signal. Do the electrons traversing the circuit
change direction? Yes. Do the electrons in a DC circuit ever change
direction? No.

Ergo, because of the periodic polarity reversals what you're looking
at is AC.

And, according to what you've said in other posts, if that were a
0.6 volt peak sinewave with 1.0 volt dc, it wouldn't be.

But your definition of AC is faulty, because in fact they are the
same thing, and *both* of them contain an AC component and a DC
component, even if the general direction of electrons is always the
same.

No, both do not - only one of the 1 volt/.6 volt examples given has an
_alternating_ direction component - both examples do have a _variation_ in
their magnitude component.
( This is not a new discussion - and all of the dozen or so engineering
and physics texts and training manuals I have researched on the matter
adhere to the "alternating is reversing" definition of AC. It has been
custom and practice for at least 40 years.)

1) the 1 volt dc with the .6 sine variation does not alternate its
direction of flow. Its flow only varies in the magnitude of the charge
flowing always in one direction.
It has no alternating current ( i.e, it has no regularly reversing, i.e.
_alternating_, charge flow direction)

2) the 1 volt sinewave with the .6 volt dc does reverse charge flow
direction. It is alternating in its flow direction.
It also varies in its magnitude.

The direction of the description vector must alternate in order to have
Alternating Current. If it does not change direction but only varies in
magnitude, the descriptive vector is not alternating, it is merely varying
in magnitude.

3) Impedance laws apply equally to varying DC and to AC.

---

Looking at the Fourier terms makes this waveform perfectly clear.
Calling it "AC" or "DC" does not.

---
Why go there? Your description was adequate to indicate that polarity
reversals occur, therefore making the signal voltage alternate between
two different polarities, therefore making the current alternate
between polarities as well. That's why it's called "Alternating
Current".

Except, polarity reversals are not significant to the definition
of AC.

---

"AC" or "DC" are gross and meaningless oversimplifications.

---
Uh-huh...

He's right.

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson
Ukpeagvik (Barrow, Alaska) floyd@barrow.com

 

[NSM]

"Choreboy" <choreboyREMOVE@localnet.com> wrote in message
news:42ABDF7C.3A0374F4@localnet.com...

To call a waveform an AC sine wave implies that there is no DC, but this
thread is the first time I've read the claim that all sine waves are AC
sine waves.

FWIW, most waveforms can be created as the sum of sine waves. I wrote an
interesting computer demo once that showed how a sine and it's harmonics
could be added graphically to form a better and better approximation of a
square wave, running through what looked like Butterworth etc. responses.

N

 

[NSM]

<mabelmapleleaf@yahoo.com> wrote in message
news:1118590198.830359.285980@g43g2000cwa.googlegroups.com...

PS It's a shame you have to weed thru all the crap from some
of the posters here who have a lot of time on their hands and
have no tolerance for those who are just learning their craft....

Who do you want operating on your gall bladder? Someone who knows what he is
doing or someone who is making it up as he goes along?

N

 

[NSM]

"Arfa Daily" <monitech@ntlworld.com> wrote in message
news:R84re.7708$q46.1371@newsfe1-win.ntli.net...

I don't know where you would get the idea that your power was an upgrade
on
ours. We NEVER EVER get brownouts here. This is largely because the higher
voltages we use on our crosscountry distribution network, allows for lower
transmission currents, which result in lower voltdrops at any resistance
points at junctions.

We can also run high watts appliances such as ovens and driers, without
having to use cables as thick as your arm, and 6 inch nails for fuses. Oh,
and we also did away with ugly overheads and pole mounted transformers at
street distribution level, years ago ....

So your system is an upgrade ?? Hmmmm ...

Yep. It still surprises me that the lights here dim everytime a heater
switches on. Weird.

N

 

[NSM]

"Tristan Beeline" <mist_distance@hotmail.com> wrote in message
news:55f4364e.0506121950.19b23dbc@posting.google.com...

I accidently killed my lab assistant with my new railgun and his body
is badly damaged.

Do you think I can repair the body with some electronic parts, so that
it will work again or should I throw it away and get a new one ?

Just beam him back using the stored parameters in the transporter system and
dispose of the extra body into space.

N

 

[NSM]

"Do Little2" <listed@space.com> wrote in message
news:IJ5re.2791$EP2.13759@newscontent-01.sprint.ca...

So your system is an upgrade ?? Hmmmm ...

True, serving about 330 million people,
compared to a few on a little island is
a real big upgrade...

Really? And one squirrel or untrimmed tree blacks out power to half the
continent? Special!

N

 

[NSM]

"Michael Kennedy" <Mikek400@nearthlink.net> wrote in message
news:veqdnbrYhPH5ijDfRVn-jg@comcast.com...

Loony? I don't think so. We will know the answer to this question one day.

You'll be dead. You won't know anything.

N

 

[NSM]

"Don Lancaster" <don@tinaja.com> wrote in message
news:3h41gcFf1oqoU1@individual.net...

"AC" or "DC" are gross and meaningless oversimplifications.

True but pointless. We know what we mean. Even 'current' is a borrowed term
used as an analogy as is 'potential' or even 'pressure'. If we have voltage
surely we should only speak of amperage.

N

 

[Arfa Daily]

Well, actually, our " little island ", as you so quaintly put it, is
actually connected to many millions of other users in mainland Europe, to
form a hedged power distribution system which doesn't suffer from cascade
failure when the weather gets a bit cold, or major outages when the sun
flares a bit ... ; -)


"Do Little2" <listed@space.com> wrote in message
news:IJ5re.2791$EP2.13759@newscontent-01.sprint.ca...

"Arfa Daily" <monitech@ntlworld.com> wrote in message
news:R84re.7708$q46.1371@newsfe1-win.ntli.net...

We can also run high watts appliances such as ovens and driers, without
having to use cables as thick as your arm, and 6 inch nails for fuses.
Oh,
and we also did away with ugly overheads and pole mounted transformers at
street distribution level, years ago ....

So your system is an upgrade ?? Hmmmm ...

True, serving about 330 million people,
compared to a few on a little island is
a real big upgrade...

Dolittle2

 

[Dave Plowman (News)]

In article <IJ5re.2791$EP2.13759@newscontent-01.sprint.ca>,
Do Little2 <listed@space.com> wrote:

So your system is an upgrade ?? Hmmmm ...

True, serving about 330 million people,
compared to a few on a little island is
a real big upgrade...

Did you know there are approximately 10 times more fires per capita in the
US than the UK caused by poor or inadequate house wiring?

--
*I yell because I care

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[kip]

Very simply just put replace the Heart with a " Line Locking Palana Phase
Shift Register Module " and you should be OK .

kip
"Tristan Beeline" <mist_distance@hotmail.com> wrote in message
news:55f4364e.0506121950.19b23dbc@posting.google.com...

I accidently killed my lab assistant with my new railgun and his body
is badly damaged.

Do you think I can repair the body with some electronic parts, so that
it will work again or should I throw it away and get a new one ?

 

[daestrom]

"Floyd L. Davidson" <floyd@barrow.com> wrote in message
news:87r7f7vvlr.fld@barrow.com...

"operator jay" <none@none.none> wrote:

It is not changing polarity. I would hesitate to call it alternating
current. On the "dc sine wave" issue, I wouldn't even get into that
debate.
To me the terms involved are open to too many interpretations. As
evidenced
in this thread, I suppose.

Where *do* you get this requirement for changing polarity? We
don't call it "Alternating Polarity", we call it "Alternating
Current". If the current is being altered, it's AC. You keep
talking about AP, and it isn't the same.

'Alternating' is not the same as 'altering'. "Alternating current" is an
electrical current where the magnitude and *direction* [emphasis added]
varies cyclically.

http://en.wikipedia.org/wiki/Alternating_current

One may 'alter' the magnitude of a DC current without it becoming
'alternating current'

daestrom

 

[daestrom]

"Floyd L. Davidson" <floyd@barrow.com> wrote in message
news:87d5qrxfdn.fld@barrow.com...

John Fields <jfields@austininstruments.com> wrote:
On Sun, 12 Jun 2005 14:00:23 -0800, floyd@barrow.com (Floyd L.
Davidson) wrote:

My point still stands, that if the current is changing, it is by
definition AC, and current not changing is DC. Trying to look
at it as DC is all in one direction and anything else is AC,
doesn't work.

---
Your point is flawed. Alternating Current, by definition, causes
electrons to move in one direction for a time, and then to reverse
direction for a time.

That isn't true.

It is true by most definitions of 'Alternating Current'.
http://en.wikipedia.org/wiki/Alternating_current

'Alternating' means both magnitude and direction vary over time. A current
that varies in magnitude but not direction is not 'alternating'.

Since the voltage varies, the current will also, but the _direction_
in which the electrons are travelling will never change.

If it varies, it's AC.

Only by your apparent definition. But your definition does not agree with
the established industry.

That means that the signal is DC. A varying DC, but DC nonetheless.

If there is such a think as "varying DC", connect a load to
it... through a capacitor. Now, how do you describe the effect
that load has on your "varying DC". The load see's *only* AC,
even according to your definition. That AC came from somewhere,
and it certainly was not generated by the capacitor.

By adding a capacitor in series, you have altered the circuit. The
capacitor filters out the DC component of a the original varying DC voltage
applied. The capacitor has a varying DC voltage across it, but it never
changes polarity (you can use an electrolytic capacitor that is polarity
sensitive without damage).

The current through the resulting series circuit *does* alternate in
magnitude and *direction*, even though the voltage applied to the circuit
varies in magnitude only. So yes, the 'AC came from somewhere'. But that
doesn't mean the applied voltage is AC. Such logic is flawed. There is no
'law of conservation of AC' that says it can't be 'generated by the
capacitor'.

That's because AC is *not* defined by any change in direction,
but only by a rate of movement change.

Repeating yourself doesn't make you correct.

daestrom

 

[Wayne Tiffany]

Looks like the same one that we have at our church. Still seems to work
fine after all these years.

WT

"William R. Walsh" <newsgroups1@saveyourspam.walshcomptech.com> wrote in
message news:UNuqe.35928$x96.3790@attbi_s72...

Hello all...

In my latest round of shopping at Curbside Discount I happened across a
very
interesting Zenith VCR. It's a Model VR-1380 and the way it takes a tape
is
rather unique. The tape is loaded "sideways". So far it looks to work
apart
from some moderately tired rubber.

http://greyghost.dyndns.org/zenithvcr/ has pictures, 640x480, 47~49Kb

Anyone ever seen another VCR that does this?

William

 

[Jeff Rigby]

"John-Del" <ohger1s@aol.com> wrote in message
news:1118664585.007939.149990@g49g2000cwa.googlegroups.com...

I did a house call on a Toshiba 36HF12 that the complain was no
picture. I had repaired this about 6 months ago for vertical
shrinkage, and it's been running fine till now.

It develops 32KV HV, filament, 250 kine supply, G2, and all secondary
diodes sources off the fly are normal. The cathode voltages on all
three cathodes are high rail. I didn't have a scope with me, but the
60hz vertical "growl" from the yoke is unmistakable, so I know it has
vertical deflection. The G2 voltage varies from 200 to 850VDC.
Carefully raising the G2 to maximum induces no light whatsoever on the
CRT.

I brought in my old B&K 467 and hooked it up to the CRT with clipleads,
and the tube reads DEAD, like maybe the G2 or G1 pin is disconnected.
The TV is just over 2 years old, but the customer is going to try to
see if Toshiba will cough up a CRT.

Has anyone seen one of these do this?


John
Cathode voltage rail high means the tube is turned off. It's an electonic

problem in the video out circuitry. Kine bias circuit?

 

[Floyd L. Davidson]

"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote:

"Floyd L. Davidson" <floyd@barrow.com> wrote in message
news:87d5qrxfdn.fld@barrow.com...
John Fields <jfields@austininstruments.com> wrote:
On Sun, 12 Jun 2005 14:00:23 -0800, floyd@barrow.com (Floyd L.
Davidson) wrote:

'Alternating' means both magnitude and direction vary over time. A current
that varies in magnitude but not direction is not 'alternating'.

Then you'll have a very difficult time explaining now a
transistor amplifier works if it uses AC coupling that involves
capacitors.

Since the voltage varies, the current will also, but the _direction_
in which the electrons are travelling will never change.

If it varies, it's AC.

Only by your apparent definition. But your definition does not agree with
the established industry.

Which industry? You can't do AC circuit analysis with any other
definition.

If there is such a think as "varying DC", connect a load to
it... through a capacitor. Now, how do you describe the effect
that load has on your "varying DC". The load see's *only* AC,
even according to your definition. That AC came from somewhere,
and it certainly was not generated by the capacitor.

By adding a capacitor in series, you have altered the circuit. The

Capacitors don't generate voltage or current. The circuit
alteration merely demonstrates that the voltage and current on
one side meets all of your requirements, while the identical
charge flow on the other side does not, which indicates a flaw
in your specification.

capacitor filters out the DC component of a the original varying DC voltage
applied.

Yes, which leaves the AC that was there all along. It's AC
after, and it was AC before. If you do circuit analysis the
treatment is exactly the same on both sides of the capacitor.

The capacitor has a varying DC voltage across it, but it never
changes polarity (you can use an electrolytic capacitor that is polarity
sensitive without damage).

Exactly. Yet there *is* current through the capacitor, which
only passes AC. That AC current isn't generated inside that
capacitor. It comes out one side, so it *had* to be coming in
the other side.

The current through the resulting series circuit *does* alternate in
magnitude and *direction*, even though the voltage applied to the circuit
varies in magnitude only. So yes, the 'AC came from somewhere'. But that
doesn't mean the applied voltage is AC. Such logic is flawed. There is no
'law of conservation of AC' that says it can't be 'generated by the
capacitor'.

That's hilarious. DC applied to a capacitor generates AC????

I don't think so.

That's because AC is *not* defined by any change in direction,
but only by a rate of movement change.

Repeating yourself doesn't make you correct.

Won't help your point either. And it makes no difference how many
places you find it ill defined either.

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@barrow.com

 

[Floyd L. Davidson]

"operator jay" <none@none.none> wrote:

"Floyd L. Davidson" <floyd@barrow.com> wrote:

Picture my flashlight, battery powered. Generally this is considered a dc
circuit. When I turn it on or off, there is 'change'.

You were doing pretty good up to that point.

So is it in fact an
AC flashlight?

No. But that doesn't mean there is never any AC present in the
circuit.

It happens that with a battery powered flashlight that is rare
(but predictable too), and of no consequence whatever. It can
be ignored in design and operation of the flashlight. But that
doesn't mean there is never any AC in the circuit, or that there
are no circuits where it is significant.

If the battery starts to die there is a change so is it in
fact an AC battery? Etcetera. (These questions are rhetorical by the way).
I know better than to try to pin a strict name on these things where there
is not an (adequately) universal and strict definition.

Every time you flip the switch on or off, there is AC in that
circuit.

You can probably prove it too, relatively easy. Tune an AM
receiver to a frequency where no station is being received, and
hold the flashlight up close to the antenna. Flip it on and off
a few times. I suspect, though I haven't actually tried this,
that you'll hear a pop in the radio's speaker almost every time
you flip the switch. That is because some of the AC produced by
flipping that switch is RF.

On another note, how long are the days getting to be way up there? Do you
get continuous sunshine?

It's been 24 hours of daylight for quite some time now. The sun
hasn't actually gone down for a month (May 10th), but of course
we had 24 hours of light long before that. The next time it
gets below the horizon will be August 1, and it will be late
August before it gets "dark".

The temperature is 30F right now, with a reported 18 mph wind and
fog. It was gusting up to 30 mph last night. It probably won't get
much warmer than maybe 36F today.

That is actually very comfortable weather, mostly because it is
unlikely to rain. I hate getting wet...


--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@barrow.com

 

[Floyd L. Davidson]

"Kevin Aylward" <see_website@anasoft.co.uk> wrote:

Don Lancaster wrote:
"AC" or "DC" are gross and meaningless oversimplifications.

That's going a bit far. "Meaningless" means no meaning, and that is not
really an accurate description for the terms AC and DC. They have a
pretty well understood meaning, despite some suggestions in this thread.

Given the significant experience of several people involved in
this discussion, and the wide variety of interpretations they
are giving to those terms, it would seem that just about the
*only* thing one could positively take away from this particular
discussion is that, as Don says, those terms are meaningless.

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@barrow.com