sci.electronics.repair - 25 new messages in 8 topics - digest

sci.electronics.repair
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Today's topics:

==============================================================================
TOPIC: Another reason to hate CFLs ...
http://groups.google.com/group/sci.electronics.repair/t/87ea27a2579f0316?hl=en
==============================================================================

== 1 of 5 ==
Date: Sun, Oct 24 2010 4:29 pm
From: "Wild_Bill"

I've been buying various brands of CFLs in the U.S. for about 5 years, and
initially, they seemed more problematic than they might be worth.
The early ones were slow to attain their full brightness, colors of light
were yellowish and reddish, and typically failed within a year.

The CFLs that I've found to provide "good" lighting, are the daylight or
sunlight versions (various brands).
Most of my lighting in living areas have fixtures that orient the lamps
base-down, and the result is bounce lighting from overhead and adjacent wall
surfaces. This type of lighting is very agreeable to me, and I don't
particularly like to have a lamp shining directly onto something I'm looking
at, unless I'm trying to get a close look at something within a piece of
equipment.

Placing a cool or soft-white CFL near a 6000 degree daylight CFL, with both
lighting a white wall, should reveal a very different color of light coming
from the cool/soft lamp. The cool or soft-white CFLs were making many colors
appear to be different in my comparisons.

Early on, I was glad to discover that CCD and digital camera devices worked
very well with the higher light temperatures of 5000+.
Around 6500 degrees works very well for my eyes and camera images, in my
experience.

In the workshop, I found that the light from cheap workshop/garage
cool/soft-white fluorescent twin tube fixtures was slightly uncomfortable
(for my eyes), and that issue was fixed by also having a few regular
incandescent bulbs in the work area. The result was an improvement but not
as good as sunlight CFLs (for my eyes).

--
Cheers,
WB
.............

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:PYLwo.42936$vi1.18039@newsfe07.ams2...
> As if any more reasons were needed on top of their horrible startup
> characteristics, their ugliness, their sick coloured light, and their
> inability to last for a fraction of the claimed lifetime :-(
>
> Like most of us, I suspect, I have hundreds of component drawers, which
> over the years have become mixed up and confused, so in the circumstances
> of work being very quiet at the moment, I decided to have a major tidy up
> and clear out of redundant components. As a first move, I decided to
> rationalise the resistors, and re-store them by individual value, rather
> than in groups of values in the same drawer.
>
> Now the other day, the bulb in my Anglepoise bench light failed, and as it
> was the last 60 watt pearl one I had - nowhere stocking such an animal any
> more due to EU ecobollox intervention - I put in a CFL that had come free
> in a cornflake packet or some such nonsense. Once it has warmed up in the
> morning - at least one coffee drinking time needed for this - it seemed to
> work reasonably well. Until, that is, I started trying to identify the
> resistors in my old drawers to move them into the individual value drawers
> in the new location.
>
> The spectrum from this lamp is so poor and discontinuous, that it is
> almost impossible to resolve red from brown from orange, or violet from
> blue or grey. Absolutely bloody useless. If I can't find any more 60 watt
> pearl bulbs on the 'net, then I'm going to modify the lampholder to take a
> low voltage halogen downlighter bulb, and hook it to a 12v transformer.
>
> Arfa

== 2 of 5 ==
Date: Sun, Oct 24 2010 6:20 pm
From: "Arfa Daily"

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:r7m8c65k3gk87gsfbi3ivv1o5jhv7r9cfi@4ax.com...
> On Sat, 23 Oct 2010 22:08:20 -0700, Jeff Liebermann <jeffl@cruzio.com>
> wrote:
>
>>On Sun, 24 Oct 2010 02:28:14 +0100, "Arfa Daily"
>><arfa.daily@ntlworld.com> wrote:
>>
>>>Now the other day, the bulb in my Anglepoise bench light failed, and as
>>>it
>>>was the last 60 watt pearl one I had - nowhere stocking such an animal
>>>any
>>>more due to EU ecobollox intervention
>
> More...
>
> "Emission spectra of some compact fluorescent lamps"
> <http://web.ncf.ca/jim/misc/cfl/>
>
> You can check the spectra of some CFL lamps at:
> <http://www.lamptech.co.uk/Compact%20Fluorescent.htm>
>
> "The Double Amici Prism Hand-Held Spectroscope."
> Emission spectra of various lamps are furthur down the page.
> <http://ioannis.virtualcomposer2000.com/spectroscope/amici.html>
> Incidentally, you might find it amusing to see what CCFL backlit white
> looks like on a laptop LCD display [1.3.7], and a Sony Trinitron
> [1.11.3]. Also, the authors comments on "Full-Spectrum Lamps" near
> the bottom of the page.
>
> --
> Jeff Liebermann jeffl@cruzio.com

Thanks for the links, Jeff. Very interesting reading, as always. The last
one shows very clearly why the human animal is 'at ease' with daylight,
incandescent light, light from fire and so on, but in some cases - notably
*me* for instance - not with the light from CFLs. The discontinuity and lack
of general 'body' to the spectrum is very telling. Also, interesting to see
the spectrum from regular linear flourescent tubes. Those diagrams show me
very clearly why I don't have a problem with the light from them. That just
leaves (and begs) the question of why, when broad spectrum phosphors are
obviously readily and cheaply available, as evidenced by their use in linear
tubes, they are not using them in CFLs, instead pissing about with limited
bandwidth emission triphosphor coatings, which produce the objectionable
light quality that I, and others like me, are being forced to endure. Do the
CFLs on sale in other parts of the world, in fact use linear tube phosphors
?

Arfa

== 3 of 5 ==
Date: Sun, Oct 24 2010 6:38 pm
From: "Arfa Daily"

"Rich Webb" <bbew.ar@mapson.nozirev.ten> wrote in message
news:dhq8c6d4ek9ttcgf1svi8fthaa6hhn0dtl@4ax.com...
> On Sun, 24 Oct 2010 09:46:06 -0700, Jeff Liebermann <jeffl@cruzio.com>
> wrote:
>
>>On Sat, 23 Oct 2010 22:08:20 -0700, Jeff Liebermann <jeffl@cruzio.com>
>>wrote:
>>
>>>On Sun, 24 Oct 2010 02:28:14 +0100, "Arfa Daily"
>>><arfa.daily@ntlworld.com> wrote:
>>>
>>>>Now the other day, the bulb in my Anglepoise bench light failed, and as
>>>>it
>>>>was the last 60 watt pearl one I had - nowhere stocking such an animal
>>>>any
>>>>more due to EU ecobollox intervention
>>
>>More...
>>
>>"Emission spectra of some compact fluorescent lamps"
>><http://web.ncf.ca/jim/misc/cfl/>
>>
>>You can check the spectra of some CFL lamps at:
>><http://www.lamptech.co.uk/Compact%20Fluorescent.htm>
>>
>>"The Double Amici Prism Hand-Held Spectroscope."
>>Emission spectra of various lamps are furthur down the page.
>><http://ioannis.virtualcomposer2000.com/spectroscope/amici.html>
>>Incidentally, you might find it amusing to see what CCFL backlit white
>>looks like on a laptop LCD display [1.3.7], and a Sony Trinitron
>>[1.11.3]. Also, the authors comments on "Full-Spectrum Lamps" near
>>the bottom of the page.
>
> Cool stuff. Always interesting to "see" that what we perceive is not
> always (or often) 1:1 with what's really there.
>
> Make Magazine vol 24 (due out any day now) will have a DIY article on a
> hand-held diffraction grating spectroscope.
> http://makezine.com/magazine/ (Note that as of today the link shows
> volume 23; subscribers should have received an email link to number 24).
>
> There's also http://sciencefirst.com/product_info.php?products_id=403.
> It's kind of clunky (basically a kid's toy) but it does have an
> adjustable scale so it can be kinda-sorta calibrated using a known
> spectral line from a fluorescent lamp.
>
> --
> Rich Webb Norfolk, VA

I wonder whether colour blindness has anything to do with this, and the
reason why some of us seem to have a problem with the colour rendition of
CFLs, whilst others don't ? Long ago when I was in senior school, I was
tested for colour blindness, and was declared red blind and green
insensitive (I think) which I understood to mean that I couldn't pick out
certain shades of green amongst other colours, and couldn't see some shades
of red at all. In normal everyday life, this has never caused me any
problem, and as far as I am concerned, I see and distinguish colour as well
as the next guy, (although maybe differently in perception) but that is
assuming the natural condition of daylight, which all of the 'traditional'
light sources, including linear flourescents, mimic reasonably well, at
least at the lower end, and in terms of the spectra being reasonably 'bulky'
and continuous. However, that is not the case for the typical CFL spectrum,
which is *extremely* discontinuous. Could it be that the zero emission dips
in the spectrum, correspond wholly or in part, to spectrum sensitivity
deficiencies in my eyes, causing my colour blindness to become significant
under that light, and leading to some colours all but disappearing to me.
That would certainly account for why some blend colours like orange or
violet on the resistor colour bands that started all this, become
indistinguishable (to me) from the single colour components which make them
up.

Arfa

== 4 of 5 ==
Date: Sun, Oct 24 2010 6:50 pm
From: "Arfa Daily"

"LSMFT" <boleyn7@aol.com> wrote in message
news:%O2xo.761$kS.755@newsfe17.iad...
> Arfa Daily wrote:
>> As if any more reasons were needed on top of their horrible startup
>> characteristics, their ugliness, their sick coloured light, and their
>> inability to last for a fraction of the claimed lifetime :-(
>>
>> Like most of us, I suspect, I have hundreds of component drawers, which
>> over the years have become mixed up and confused, so in the
>> circumstances of work being very quiet at the moment, I decided to have
>> a major tidy up and clear out of redundant components. As a first move,
>> I decided to rationalise the resistors, and re-store them by individual
>> value, rather than in groups of values in the same drawer.
>>
>> Now the other day, the bulb in my Anglepoise bench light failed, and as
>> it was the last 60 watt pearl one I had - nowhere stocking such an
>> animal any more due to EU ecobollox intervention - I put in a CFL that
>> had come free in a cornflake packet or some such nonsense. Once it has
>> warmed up in the morning - at least one coffee drinking time needed for
>> this - it seemed to work reasonably well. Until, that is, I started
>> trying to identify the resistors in my old drawers to move them into the
>> individual value drawers in the new location.
>>
>> The spectrum from this lamp is so poor and discontinuous, that it is
>> almost impossible to resolve red from brown from orange, or violet from
>> blue or grey. Absolutely bloody useless. If I can't find any more 60
>> watt pearl bulbs on the 'net, then I'm going to modify the lampholder to
>> take a low voltage halogen downlighter bulb, and hook it to a 12v
>> transformer.
>>
>> Arfa
>
> People like you have real issues. I have had 100% CFL's in my home for
> decades. Guess what, they are better than candles.
> I will be switching to LED's when they are available for all around use.
>
> --
> LSMFT

Maybe I do have issues - see my post in this thread about colour blindness.
But setting that aside, I am sick of people telling me that I can't actually
see what I clearly can, because *they* can't see it, and are happy to be led
by the nose down the route of this substitute technology in the name of
green mist brigade ecobollox.

And you know what else ? You're right ! CFLs are better than candles. But
compared to incandescent lamps, they suck big time. So if that's the sum
total of your contribution, and you are happy with the shitstreet pieces of
crap, that's just fine.

I, and thousands of others, are not.

Arfa

== 5 of 5 ==
Date: Sun, Oct 24 2010 9:14 pm
From: Jeff Liebermann

On Mon, 25 Oct 2010 02:20:53 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

>The last
>one shows very clearly why the human animal is 'at ease' with daylight,
>incandescent light, light from fire and so on, but in some cases - notably
>*me* for instance - not with the light from CFLs. The discontinuity and lack
>of general 'body' to the spectrum is very telling.

Yep. It took me literally 20 years to get used to using ordinary
fluorescent desk lamps.

>Also, interesting to see
>the spectrum from regular linear flourescent tubes. Those diagrams show me
>very clearly why I don't have a problem with the light from them. That just
>leaves (and begs) the question of why, when broad spectrum phosphors are
>obviously readily and cheaply available, as evidenced by their use in linear
>tubes, they are not using them in CFLs, instead pissing about with limited
>bandwidth emission triphosphor coatings, which produce the objectionable
>light quality that I, and others like me, are being forced to endure. Do the
>CFLs on sale in other parts of the world, in fact use linear tube phosphors

Dunno, but I can guess that incremental improvements as a sales tool
might be at work. If the industry produced the ultimate perfect CFL
light, that lasted forever, it might as well close up shop after about
10 years. So, we have incremental improvements in order to inspire us
to "upgrade" our lighting. Perpetual obsolescence is the price of
technical progress.

This might help:
2700K (warm tone)
4100K (Cool White)
5000K (Natural Day Light)
5500K (Full Spectrum)
6500K (Day Light)
from:
<http://www.naturallighting.com/web/shop.php?crn=571>
Presumably, you're looking for 5500K, which is commonly available. For
example:
<http://www.1000bulbs.com/product/6792/FC23-SFS.html>
I don't know exactly which phosphors (or mixes) are currently in use.

I had the not-so-great idea of using my digital camera and some
software as a spectrograph. I found what I thought was some suitable
software:
<http://rsb.info.nih.gov/ij/plugins/color-inspector.html>
<http://rsb.info.nih.gov/ij/>
It's really cool software, but never obtained anything like the CFL
spectra on the various web pages. Seen any software that will take a
solid color, from a JPG of a CFL lamp, and break it up into spectral
lines?

Drivel: I was defrosting the fridge with a screwdriver and hammer,
when I managed to puncture the cooling coils, releasing the gas. I
hate days like this.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

==============================================================================
TOPIC: is this wattage accurate?
http://groups.google.com/group/sci.electronics.repair/t/9b48e563412593f0?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Oct 24 2010 5:40 pm
From: "Brenda Ann"

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:3uydndV7X_18pFnRnZ2dnUVZ_tmdnZ2d@earthlink.com...
>
> Brenda Ann wrote:
>>
>> "John Fields" <jfields@austininstruments.com> wrote in message
>> news:V-KdnbZuApXQLl7RnZ2dnUVZ_qKdnZ2d@posted.toastnet...
>> >
>> > "Brenda Ann" <newsgroups@fullspectrumradio.org> wrote in message
>> > news:m6idndzQfMfjq1_RnZ2dnVY3go-dnZ2d@giganews.com...
>> >>
>> >>
>> >> "nucleus" <rose122550@yahoo.com> wrote in message
>> >> news:54849318-33dc-43b5-aabe-0a2c690cff86@k22g2000yqh.googlegroups.com...
>> >>> for those who are energy conscious, the energy consumption of these
>> >>> LCD TVs appear to be not only low but reversed:
>> >>>
>> >>> Sony Bravia 40 inch KDL-40EX401 --- 170 watts
>> >>> Sony Bravia 52 inch KDL-52EX701 --- 142 watts
>> >>>
>> >>> i recently looked at the tags on back of these sets at Sams.
>> >>
>> >> 401: Standby mode: 0.19 W
>> >> Shop mode: 146 W
>> >> Home mode: 110 W
>> >>
>> >> 701: Standby mode: 0.16 W
>> >> Home mode: 142 W
>> >>
>> >> Note: the 401 model is a standard LCD/Fluorescent backlight, while the
>> >> 701 model is an LCD/LED backlight, which is more efficient.
>> >>
>> >>
>> >
>> > That's BS, Where do you get it from Punk?
>> >
>>
>> 1) What is supposed to be BS? The specs come directly from the Sony
>> website.
>> Also, it's a fact that LED backlights use ~40% less energy than
>> fluorescent
>> backlights. Our Sharp Aquos uses only 85-100 watts depending upon scene
>> brightness.
>>
>> 2) Do you kiss your mother with that mouth?
>
>
> Brenda, you are being trolled, and the troll is impersonating someone
> from another electronics group. The real John Fields is a little rough
> around the edges, but a good guy. This group isn't like RARP. There
> are a lot of trolls on the sci.electronics.* newsgroups.
>

Understood... and my apologies to the real John Fields.

To PeterD: the apology stands, but reading headers doesn't mean much when
you have not seen the original nym's posts before, and have no point of
reference.

== 2 of 2 ==
Date: Sun, Oct 24 2010 8:43 pm
From: "John Fields"

"Brenda Ann" <newsgroups@fullspectrumradio.org> wrote in message
news:E_6dnVwD9e1wTFnRnZ2dnVY3go2dnZ2d@giganews.com...
>
>
> "Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
> news:3uydndV7X_18pFnRnZ2dnUVZ_tmdnZ2d@earthlink.com...
>>
>> Brenda Ann wrote:
>>>
>>> "John Fields" <jfields@austininstruments.com> wrote in message
>>> news:V-KdnbZuApXQLl7RnZ2dnUVZ_qKdnZ2d@posted.toastnet...
>>> >
>>> > "Brenda Ann" <newsgroups@fullspectrumradio.org> wrote in message
>>> > news:m6idndzQfMfjq1_RnZ2dnVY3go-dnZ2d@giganews.com...
>>> >>
>>> >>
>>> >> "nucleus" <rose122550@yahoo.com> wrote in message
>>> >> news:54849318-33dc-43b5-aabe-0a2c690cff86@k22g2000yqh.googlegroups.com...
>>> >>> for those who are energy conscious, the energy consumption of these
>>> >>> LCD TVs appear to be not only low but reversed:
>>> >>>
>>> >>> Sony Bravia 40 inch KDL-40EX401 --- 170 watts
>>> >>> Sony Bravia 52 inch KDL-52EX701 --- 142 watts
>>> >>>
>>> >>> i recently looked at the tags on back of these sets at Sams.
>>> >>
>>> >> 401: Standby mode: 0.19 W
>>> >> Shop mode: 146 W
>>> >> Home mode: 110 W
>>> >>
>>> >> 701: Standby mode: 0.16 W
>>> >> Home mode: 142 W
>>> >>
>>> >> Note: the 401 model is a standard LCD/Fluorescent backlight, while
>>> >> the
>>> >> 701 model is an LCD/LED backlight, which is more efficient.
>>> >>
>>> >>
>>> >
>>> > That's BS, Where do you get it from Punk?
>>> >
>>>
>>> 1) What is supposed to be BS? The specs come directly from the Sony
>>> website.
>>> Also, it's a fact that LED backlights use ~40% less energy than
>>> fluorescent
>>> backlights. Our Sharp Aquos uses only 85-100 watts depending upon scene
>>> brightness.
>>>
>>> 2) Do you kiss your mother with that mouth?
>>
>>
>> Brenda, you are being trolled, and the troll is impersonating someone
>> from another electronics group. The real John Fields is a little rough
>> around the edges, but a good guy. This group isn't like RARP. There
>> are a lot of trolls on the sci.electronics.* newsgroups.
>>
>
> Understood... and my apologies to the real John Fields.
>
> To PeterD: the apology stands, but reading headers doesn't mean much when
> you have not seen the original nym's posts before, and have no point of
> reference.

I am a sub-shit. No apologies needed Brenda.

---
JF

==============================================================================
TOPIC: If you like old dragsters...
http://groups.google.com/group/sci.electronics.repair/t/8c65ac2b95419914?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Oct 24 2010 5:55 pm
From: RoadRunner

This is a pretty cool video of a bunch of old dragsters at Crackle
Fest during the National Hot Rod Reunion.

http://www.craigboyce.com/w/2010/10/cacklefest-at-the-2010-national-hot-rod-reunion/

==============================================================================
TOPIC: OT: Is this question too challenging for a BSEE graduate?
http://groups.google.com/group/sci.electronics.repair/t/31ba2b6a402a3720?hl=en
==============================================================================

== 1 of 7 ==
Date: Sun, Oct 24 2010 6:14 pm
From: "Michael A. Terrell"

PlainBill47@yawho.com wrote:
>
> On Sat, 23 Oct 2010 13:05:23 -0700, "William Sommerwerck"
> <grizzledgeezer@comcast.net> wrote:
>
> >> Any electronics technician should be able to solve this
> >> by inspection; no calculator necessary. 3K/1k = x/40,
> >> therefore x= 120 ohms. Come up with more difficult ones
> >> next time.
> >
> >What do you mean by "inspection"? Are you applying a formula you memorized?
> >Or do you /understand/ what's involved?
> >Probably better than you do. The voltage across R1 is 1/4 of +VDC. An op-amp tries to force both inputs to the same voltage. Since it was stipulated the op-amp is a 'classic, ideal' op amp, we can assume it has none of the defects found in the real world. As a result the voltage across R3 will also be 1/4 of VDC. The only way that can happen is if the effective resistance of Q1 is 3 times the resistance of R3, or 120 ohms.
>
> NOW, what is less certain is the proper answer to the problem
> "Calculate the equivalent resistance of this programmable load."
> Given that R1, R2, and R3 are all part of the load, the proper answer
> to the original diagram is 153.846 ohms. Except that circuit does not
> show any evidence of being 'programmable'.

You 'program' it by changing reistors.

--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

== 2 of 7 ==
Date: Sun, Oct 24 2010 6:27 pm
From: hamilton

On 10/24/2010 4:55 PM, TheGlimmerMan wrote:
> On Sat, 23 Oct 2010 13:28:58 -0700 (PDT), linnix<me@linnix.info-for.us>
> wrote:
>
>> On Oct 23, 1:25 pm, hamilton<hamil...@nothere.com> wrote:
>>> On 10/23/2010 1:35 PM, linnix wrote:
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>> On Oct 23, 12:27 pm, "William Sommerwerck"
>>>> <grizzledgee...@comcast.net> wrote:
>>>>>>> I don't think this is a very good "quiz" question,
>>>>>> It is a good quiz for fun, but not a good interview question.
>>>>>> What does it prove? The candidate is a good quiz solver?
>>>>>> It has no real engineering use. Are they hiring quiz solver
>>>>>> or engineer?
>>>
>>>>> It's a great interview question. It shows whether the candidate can cut
>>>>> through the clutter and see the basic principle involved. A good engineer
>>>>> needs to be able to do that.
>>>
>>>> But do you base your hiring/firing decision on whether he can do it
>>>> during the interview? Most engineers can solve it in more relaxed
>>>> environment, in the real world. It only proved that many can't do it
>>>> under pressure, during the interview.
>>>
>>> Maybe the OP is showing the new hire what to expect from the new manager.
>>>
>>> Silly tests like this shows how a manager will behave after being hired.
>>>
>>> These tests work both ways.
>>>
>>> h
>>
>> Yes, usually they are sweat shops hiring slaves.
>
>
> Not if you have a title.

"Slave" is a title.

;-)

== 3 of 7 ==
Date: Sun, Oct 24 2010 6:48 pm
From: David Nebenzahl

On 10/24/2010 3:19 PM brent spake thus:

[snip quiz]

> It is pretty easy if you know about how the op-amp will do whatever it
> can to make the voltage at pin 2 the same as pin 1.

But is this really true? This sounds like it might be either a gross
oversimplification or a possible falsehood.

DISCLAIMER: I'm just learning about this stuff. OK, I've been fooling
around with electronics for, lessee, about 40 years now, but have had no
formal training; I'm trying to rectify that by reading and studying.

So today I read up about op amps. Learned how a comparator works,
generally speaking. How they differ from op amps (open loop).

My understanding of a comparator is that the output will be forced to
one extreme or the other depending on the difference in voltage between
noninverting and inverting inputs. Any significant voltage difference
will drive the output to near the respective supply rail, positive or
negative.

But I don't see how an op amp can, to quote brent, "do whatever it can
to make the voltage[s the same]". After all, these are *inputs*, no? So
at least in the case of a comparator, let's say that there exists a
1-volt difference between noninverting and inverting inputs (which I
understand is a *huge* difference given the extremely high gain of the
amp). Let's say the difference is positive: this will drive the output
close to the + rail, correct? But the noninverting input will still be 1
volt positive w/respect to the inverting input, right? In other words,
the change in output doesn't affect the inputs.

Now, this may be different in other configurations (operational or
instrumentation amp), where there are connections between output and
input instead of open loop. So is it true that in these cases the inputs
will be forced to (near) equal? If so, how does that work?

This still sounds rather mysterious to me.

--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

== 4 of 7 ==
Date: Sun, Oct 24 2010 7:10 pm
From: brent

On Oct 24, 9:48 pm, David Nebenzahl <nob...@but.us.chickens> wrote:
> On 10/24/2010 3:19 PM brent spake thus:
>
> [snip quiz]
>
> > It is pretty easy if you know about how the op-amp will do whatever it
> > can to make the voltage at pin 2 the same as pin 1.
>
> But is this really true? This sounds like it might be either a gross
> oversimplification or a possible falsehood.
>
It is a simplification, sort of. This simplification is assuming a
few things:

1. It assumes a stable feedback arrangement. Knowing if something is
stable is pretty deep into EE knowledge, but fortunately, using op-
amps allows stability to be achieved in most cases without going
through the stability analysis. This circuit feels stable by looking
at it, but there are many simple ways that a feedback circuit can go
unstable. But in a nutshell, anytime you have lots of gain (like in
an op-amp) and you try to implement a feedback circuit with the gain
(for real nice control and stability) you risk , or need to worry
about instability. Instability is when the circuit reacts so fast and
the delay is wrong and it can't make up its mind what to do so it
oscillates back and forth. You can also just screw up and put the
output on a rail too.

2. It is assuming an infinite gain opamp. This problem is a dc
(static) problem, so in reality there might be a dc gain of 100000.
This means that to achieve a voltage to control to FET there might be
like 1 uVolt of difference in voltage between the two pins. Close
enough to just say they are equal.

> DISCLAIMER: I'm just learning about this stuff. OK, I've been fooling
> around with electronics for, lessee, about 40 years now, but have had no
> formal training; I'm trying to rectify that by reading and studying.
>
> So today I read up about op amps. Learned how a comparator works,
> generally speaking. How they differ from op amps (open loop).
>
> My understanding of a comparator is that the output will be forced to
> one extreme or the other depending on the difference in voltage between
> noninverting and inverting inputs. Any significant voltage difference
> will drive the output to near the respective supply rail, positive or
> negative.
>

Correct.

> But I don't see how an op amp can, to quote brent, "do whatever it can
> to make the voltage[s the same]". After all, these are *inputs*, no? So
> at least in the case of a comparator, let's say that there exists a
> 1-volt difference between noninverting and inverting inputs (which I
> understand is a *huge* difference given the extremely high gain of the
> amp). Let's say the difference is positive: this will drive the output
> close to the + rail, correct? But the noninverting input will still be 1
> volt positive w/respect to the inverting input, right? In other words,
> the change in output doesn't affect the inputs.
>
> Now, this may be different in other configurations (operational or
> instrumentation amp), where there are connections between output and
> input instead of open loop. So is it true that in these cases the inputs
> will be forced to (near) equal? If so, how does that work?
>
> This still sounds rather mysterious to me.
>
> --
> The fashion in killing has an insouciant, flirty style this spring,
> with the flaunting of well-defined muscle, wrapped in flags.
>
> - Comment from an article on Antiwar.com (http://antiwar.com)

== 5 of 7 ==
Date: Sun, Oct 24 2010 7:19 pm
From: dplatt@radagast.org (Dave Platt)

In article <4cc4e1a0$0$2450$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

Correct, if the outputs and inputs are isolated from one another. In
this (open-loop) configuration, an op amp will behave pretty much like
a comparator... and not a terribly good one (it'll be slow to reverse
its output state after it has been driven into saturation).

>Now, this may be different in other configurations (operational or
>instrumentation amp), where there are connections between output and
>input instead of open loop. So is it true that in these cases the inputs
>will be forced to (near) equal? If so, how does that work?

Correct. What you do (in the usual closed-loop op amp configuration)
is to feed back a portion of the output, to the inverting input. This
may be a direct connection (for a unity-gain noninverting circuit), or
there may be other components between the output and inverting input,
and other connections to the inverting input as well.

In any case, the effect of this "feedback" is to create the sort of
"input forcing" you're referred to. Specifically, if the inverting
input voltage is below that of the noninverting input, the output
voltage will rise towards the positive rail... and a portion of this
voltage increase, going back through the feedback network, will raise
the voltage at the noninverting input, reducing the difference
between the two inputs. This process continues until (to a first
approximation) the two inputs are at equal voltage.

>This still sounds rather mysterious to me.

Don't feel back about that. I understand that when the concept of the
feedback-looped high-forward-gain operation amplifier was first
presented to the U.S. Patent Office, the examiner rejected the
invention, claiming that it couldn't work and thus couldn't possibly
be useful.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

== 6 of 7 ==
Date: Sun, Oct 24 2010 7:26 pm
From: "tm"

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4cc4e1a0$0$2450$822641b3@news.adtechcomputers.com...
> On 10/24/2010 3:19 PM brent spake thus:
>
> [snip quiz]
>
>> It is pretty easy if you know about how the op-amp will do whatever it
>> can to make the voltage at pin 2 the same as pin 1.
>
> But is this really true? This sounds like it might be either a gross
> oversimplification or a possible falsehood.
>
snippers
>
> But I don't see how an op amp can, to quote brent, "do whatever it can to
> make the voltage[s the same]". After all, these are *inputs*, no? So at
> least in the case of a comparator, let's say that there exists a 1-volt
> difference between noninverting and inverting inputs (which I understand
> is a *huge* difference given the extremely high gain of the amp). Let's
> say the difference is positive: this will drive the output close to the +
> rail, correct? But the noninverting input will still be 1 volt positive
> w/respect to the inverting input, right? In other words, the change in
> output doesn't affect the inputs.
>
> Now, this may be different in other configurations (operational or
> instrumentation amp), where there are connections between output and input
> instead of open loop. So is it true that in these cases the inputs will be
> forced to (near) equal? If so, how does that work?
>
> This still sounds rather mysterious to me.
>
>

You are neglecting (negative) feedback. In its simplest form, the output
connects back
to the negative (inverting) input. Now it is the basic voltage follower.
Used as
a buffer in real life.

So, given your initial conditions, the positive (non-inverting) input is set
to 1 volt. The op-amp will drive the output in the positive direction until
both inputs are equal, or at 1 volt.

Regards,
tm

== 7 of 7 ==
Date: Sun, Oct 24 2010 11:04 pm
From: isw

In article <ia141b$kad$1@news.eternal-september.org>,
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

> >> The principle is this... In a stable op-amp circuit, the
> >> feedback forces the inverting and non-inverting inputs
> >> /to have the same voltage/. The rest is trivial arithmetic.
>
> > That statement is so significant, and so rarely understood...
>
> Indeed. National Semiconductor used to have an on-line course in op-amp
> circuit design, and this principle -- which should be the very first words
> out of the instructor's mouth -- is nowhere stated. Shame on you, Bob, shame
> on you.
>
> In case the reason isn't obvious -- an ideal op-amp has infinite gain. If
> there were /any/ voltage difference between the inverting and non-inverting
> inputs, the op-amp's output would slam up against the positive or negative
> rail.
>
> In practice, an op-amp has finite gain (usually between 100K and 1000K).
> This means the actual voltage difference has to be something other than
> zero. But it's is still so close to zero that it can be ignored for the
> purposes of analysis.
>
> By the way, I cut my op-amp teeth nearly 40 years ago on the wonderful
> Philbrick brook. One of the greatest pieces of technical writing ever (I
> keep a copy for inspiration), and still a classic.

Sounds like you predate me -- but not by much. I cut my "op-amp teeth"
on the earliest National Tech Notes (when they had that wonderful "NS"
logo where both glyphs were identical, with one rotated and flipped).

Isaac

==============================================================================
TOPIC: Panasonic Plasmas/LCDs of Past 5 years - "Volume Leveler" Function
http://groups.google.com/group/sci.electronics.repair/t/192fcec79e92313a?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Oct 24 2010 6:48 pm
From: ChrisCoaster

Where to set the damn thing?!?! (Sorry if I posted this in wrong
N.G.)

I've scrounged everywhere including Panasonic's own website for
instructions on where to set the Volume Leveler in the audio section
of most current(2006 & up) flat-panel consumer Panasonic TVs.

At their website, you can download any PDF manual for any Panasonic TV
as long as it's from the year 2003 or earlier(!)

At the websites offering free downloads of manuals up to last
year(basically current), you see the actual Panasonic manual but it
describes only what the function does - not where to set it! I know
what a volume leveler is - basically a limiter, but the setting on
Panasonic TVs has at least 5-7 positions.

I would appreciate anyone's help on this, particularly if you own a
recent model Panny LCD/Plasma and know where to set it to best effect.

Just not being able to find this out from the company itself is enough
of a turnoff and I will not be buying a Pansonic brand TV for any room
in my home anytime soon. To me, support is as important as the
quality of the product, and since Panny failed in that regard, they
have lost my business in the TV segment.

-CC

==============================================================================
TOPIC: How to Spot Cracks in PCB
http://groups.google.com/group/sci.electronics.repair/t/05acdc98fc4768f3?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Oct 24 2010 8:22 pm
From: Vacillator

Hi,
I think I might have some cracks in the solder or pathways on
a printed circuit board in my car's wiper motor. I have looked at the
PCB from the side that is visible to me, and have not seen any obvious
cracks or gaps. Can I remove it safely from its holder, and if so,
how? It appears to be mounted on 3 small posts. Will the PCB pop off
the posts ? I could then turn it over to look further.

Thanks

==============================================================================
TOPIC: measuring ampermeter meter internal resistance
http://groups.google.com/group/sci.electronics.repair/t/27f050235cfa3de3?hl=en
==============================================================================

== 1 of 7 ==
Date: Sun, Oct 24 2010 8:37 pm
From: "John Fields"

"Robert Baer" <robertbaer@localnet.com> wrote in message
news:-9mdnRu3coqILVnRnZ2dnUVZ_oGdnZ2d@posted.localnet...
> John Fields wrote:
>> On Sun, 24 Oct 2010 08:56:53 -0700, "Proteus" <proteusiiv@gmail.com>
>> wrote:
>>
>>
>>> PETERDUMB,
>>> YOU SKUNKS KEPT FOLLOWING EACH OTHER TO SEWER. SOON THERE WON'T BE ANY
>>> SKUNK LEFT, DON'T YOU KNOW FREAK?
>>>
>>> YOU ARENT FOOLING ANYONE STUPID
>>> YOU AND JOHNNY THERE SHOULD GIVE IT A GO
>>> YOU ARE BOTH FREAKY FAGGOTY FOOLS
>>>
>>> I AM PROTEUS
>>
>> ---
>> You are shit.
>>
>> ---
>> JF
> Who is that stupid idiot, anyway?

Flush!

== 2 of 7 ==
Date: Sun, Oct 24 2010 8:37 pm
From: "John Fields"

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:66s8c6574dm60uu3sur323fa7cg1ha9t3i@4ax.com...
> On Sun, 24 Oct 2010 08:49:42 -0500, John Fields
> <jfields@austininstruments.com> wrote:
>
> He's in California. He's posting from 66.53.26.169 which RDNS
> resolves to 66-53-26-169.lvgs.mdsg-pacwest.com, which is the dialup
> modem pool in Stockton, Calif. His message was posted through
> Toast.net, which is probably his ISP. There's a valid X-Trace header
> included. This is too easy. What I find personally amusing is that
> he's using Outlook Express for reading Usenet news, which suggests
> that he's clueless. Judging by the writing style, I would guess about
> 17 years old.
>
> $1000 fine and you can sue for damages to your reputation.
> <http://www.leginfo.ca.gov/pub/09-10/bill/sen/sb_1401-1450/sb_1411_bill_20100927_chaptered.html>
>
> --
> Jeff Liebermann jeffl@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558

Flush!

== 3 of 7 ==
Date: Sun, Oct 24 2010 8:38 pm
From: "John Fields"

"David Sanders" <sanders6320@bellsouth.net> wrote in message
news:4cc488ab$1@news.x-privat.org...
> On Sun, 24 Oct 2010 11:02:21 -0700, Jeff Liebermann wrote:
>
>> On Sun, 24 Oct 2010 08:49:42 -0500, John Fields
>> <jfields@austininstruments.com> wrote:
>>
>> He's in California. He's posting from 66.53.26.169 which RDNS
>> resolves to 66-53-26-169.lvgs.mdsg-pacwest.com, which is the dialup
>> modem pool in Stockton, Calif. His message was posted through
>> Toast.net, which is probably his ISP. There's a valid X-Trace header
>> included. This is too easy. What I find personally amusing is that
>> he's using Outlook Express for reading Usenet news, which suggests
>> that he's clueless. Judging by the writing style, I would guess about
>> 17 years old.
>>
>> $1000 fine and you can sue for damages to your reputation.
>> <http://www.leginfo.ca.gov/pub/09-10/bill/sen/sb_1401-1450/sb_1411_bill_20100927_chaptered.html>
>
> Who cares? My dick needs to be jacked.
> --
> Shit! I thought no one knew, goddammit!
> http://preview.tinyurl.com/29p4ody
> Me, jacking off! http://preview.tinyurl.com/3xpntge Available For
> Lessons!

Flush!

== 4 of 7 ==
Date: Sun, Oct 24 2010 8:39 pm
From: "John Fields"

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4cc4a7a2$0$2433$822641b3@news.adtechcomputers.com...
> On 10/24/2010 9:37 AM Fred Abse spake thus:
>
>> On Sun, 24 Oct 2010 08:53:52 -0700, Proteus wrote:
>>
>>> "Fred Abse" <excretatauris@invalid.invalid> wrote in message
>>> news:pan.2010.10.24.09.53.04.370083@invalid.invalid...
>>>
>>>> On Sat, 23 Oct 2010 21:31:15 -0700, someone calling himself "John
>>>> Fields" wrote:
>>>>
>>>>> No Stupid, that's not the way to ampmeter range to higher
>>>>> range. Why did you call yourself Superpower Punk? You don't
>>>>> even know how to multiple the power of your electronic? You
>>>>> see, I am a superdumb-ass and I am very capable to multiple
>>>>> current as well as AmpMeter by 10X.
>>>>
>>>> What a lousy impersonation.
>>>>
>>>> The John Fields that we all know (and love?) writes
>>>> grammatically.
>>>
>>> YOU ARE MORE FUCK-UP ASSHOLE FREAK!
>>>
>>> I AM PROTEUS
>>
>> http://maps.google.com/maps?ll=60.2631,-1.407736&spn=0.1,0.1&t=m&q=60.2631,-1.407736
>>
>> Plonk!
>
> So I'm just a little curious. At the risk of opening a can of worms, I
> ask:
>
> 1. How did you get this geographic location from that posting?
> 2. Who, exactly, is "Proteus"?
>
> Like I said, just curious, not dying to know ...
>
>
> --
> The fashion in killing has an insouciant, flirty style this spring,
> with the flaunting of well-defined muscle, wrapped in flags.
>
> - Comment from an article on Antiwar.com (http://antiwar.com)

Flush!

== 5 of 7 ==
Date: Sun, Oct 24 2010 8:39 pm
From: "John Fields"

"John Fields" <jfields@austininstruments.com> wrote in message
news:jl49c6he320pufp6cl6n2aqm4gp6vceuhc@4ax.com...
> On Sun, 24 Oct 2010 08:53:52 -0700, "Proteus" <proteusiiv@gmail.com>
> wrote:
>
>
>>YOU ARE MORE FUCK-UP ASSHOLE FREAK!
>>
>>I AM PROTEUS
>
> ---
> You are shit.
>
>
> ---
> JF

I am sub-shit.

---
JF

== 6 of 7 ==
Date: Sun, Oct 24 2010 8:41 pm
From: "John Fields"

"Robert Baer" <robertbaer@localnet.com> wrote in message
news:-9mdnRi3copMMlnRnZ2dnUVZ_oGdnZ2d@posted.localnet...
> Jeff Liebermann wrote:
>> On Sat, 23 Oct 2010 21:31:15 -0700, "John Fields"
>> <jfields@austininstruments.com> wrote:
>>
>>> No Stupid, that's not the way to ampmeter range to higher range. Why
>>> did you call yourself Superpower Punk? You don't even know how to
>>> multiple the power of your electronic? You see, I am a superdumb-ass
>>> and I am very capable to multiple current as well as AmpMeter by 10X.
>>> JF
>>
>> New York Makes Internet Impersonation a Crime
>> <http://www.hunton.com/files/tbl_s10News/FileUpload44/15889/new_york_internet_impersonation_privacy_alert.pdf>
>>
>> California Bans Malicious Online Impersonation
>> <http://www.pcworld.com/businesscenter/article/206469/california_bans_malicious_online_impersonation.html>
>>
>> etc...
>>
> And....So....Your point?

He wanted to say I am a piece of shit

I am actually a sub-shit.

---
JF

== 7 of 7 ==
Date: Sun, Oct 24 2010 9:40 pm
From: David Nebenzahl

On 10/24/2010 8:39 PM John Fields spake thus:

> "David Nebenzahl" <nobody@but.us.chickens> wrote in message
> news:4cc4a7a2$0$2433$822641b3@news.adtechcomputers.com...
>
>> So I'm just a little curious. At the risk of opening a can of
>> worms, I ask:
>>
>> 1. How did you get this geographic location from that posting? 2.
>> Who, exactly, is "Proteus"?
>>
>> Like I said, just curious, not dying to know ...
>
> Flush!

My full house beats your flush.

--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

==============================================================================
TOPIC: See Aishwaryarai Hot Sex Marriage & first night Videos
http://groups.google.com/group/sci.electronics.repair/t/8a7578199b1c62dd?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Oct 24 2010 9:28 pm
From: paypal cash

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http://bestindiannews.co.cc

Due to high sex content, i have hidden the videos in an image.
in that website on Right side below search box click on image and
watch videos in all angles.

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