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

sci.electronics.repair
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Today's topics:

==============================================================================
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 3 ==
Date: Mon, Oct 25 2010 12:48 am
From: "William Sommerwerck"

It's remotely possible there is no way to adjust it.

I'd suggest pouring a glass of your favorite beverage, then working
carefully through the set's menus. If there is an adjustment, you /will/
find it. You might have to look very closely, though.

== 2 of 3 ==
Date: Mon, Oct 25 2010 4:48 am
From: "Wild_Bill"

It's possible that you will find it in the on-screen menu feature, maybe in
the Audio section, but you may not recognize the "name" of the setting if
they chose to make one up (as a different company did for the LCD TV that I
bought about a year ago).

The cheap LCD TV I have, has unusual abbreviated names for menu settings,
that I've never seen before.

So, if the settings are meant/provided to be adjusted by the end user, you
might try changing them and see what has changed (the changes may not take
effect until the menu is exited).

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

"ChrisCoaster" <ckozicki@snet.net> wrote in message
news:a293e97a-1746-4951-9a54-4c46d7469f17@p26g2000yqb.googlegroups.com...
> 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

== 3 of 3 ==
Date: Mon, Oct 25 2010 5:58 am
From: Meat Plow

On Sun, 24 Oct 2010 18:48:58 -0700, ChrisCoaster wrote:

> 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.
>

It may be in a service mode menu if you've looked through every on screen
menu on the customer level.

--
Live Fast, Die Young and Leave a Pretty Corpse

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

== 1 of 12 ==
Date: Mon, Oct 25 2010 2:19 am
From: Jeffrey Angus

On 10/24/2010 11:14 PM, Jeff Liebermann wrote:
> 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.

I just use a garden hose hooked to the hot water heater.

(Ever since I ruined on with a screwdriver)

Jeff

== 2 of 12 ==
Date: Mon, Oct 25 2010 4:43 am
From: "Brenda Ann"

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:ia3bqd$ktb$1@news.eternal-september.org...
>
> Peter Wensberg, a vice-president at Polaroid, reported that Dr Land ran
> the
> entire book of color-perception charts past him, and said he was the first
> person he'd met who failed every one. Whether this meant Mr Wensberg could
> not see color at all, I don't know. But he couldn't /distinguish/ them
> very
> well.
>
> A co-worker once asked me to help with selecting colors for a page he was
> designing. It turned out he had red-green problems. I showed him a
> fluorescent-green pen. "What color does that look like to you?" "Orange".
> I
> don't know what "orange" looked like to him, but he couldn't distinguish
> that green from orange.
>

I have an hypothesis that I wish there were a way to explore. Whereas a
given color of light (or what we call a color) is a definate wavelength, and
therefore a constant.... BUT.. is human perception of colors universal? ie
we know when we are seeing "red" (~650nm) because that's what we LEARNED to
call the color we see as red. Does this necessarily mean that we are all
perceiving the same hue, or do we each see something a bit different, but we
all call it the same thing?

As a totally out of the park example: let's say you and your friend are
looking at a stopsign. You both know that the sign is "red". But perhaps
what you see is more of an orange, whilst your friend sees something more
like yellow. As a subjective appearance, the difference in color perception
would be "normal" to the viewer, whereas were the two of you to "swap"
perceptions, the world around you would look quite strange.

It may sound like a very offbeat idea, but when you think about it, most
sensors have a skew in one direction or another: no two cameras register
color exactly the same.

Just another strange thought to ponder.. :)

== 3 of 12 ==
Date: Mon, Oct 25 2010 5:23 am
From: "William Sommerwerck"

> I have an hypothesis that I wish there were a way to explore. Whereas a
> given color of light (or what we call a color) is a definate wavelength,
and
> therefore a constant... BUT... is human perception of colors universal? ie
> we know when we are seeing "red" (~650nm) because that's what we
> LEARNED to call the color we see as red. Does this necessarily mean
> that we are all perceiving the same hue, or do we each see something
> a bit different, but we all call it the same thing?

It would be very odd if what I call "blue" looks like what you would call
"red", as most human beings are chemically and neurologically essentially
identical.

However, I noticed many years ago that my eyes differ slightly. One has a
(very) slightly "cooler" or "bluer" balance. Why, I don't know.

== 4 of 12 ==
Date: Mon, Oct 25 2010 5:18 am
From: Rich Webb

On Mon, 25 Oct 2010 20:43:01 +0900, "Brenda Ann"
<newsgroups@fullspectrumradio.org> wrote:

>
>
>"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
>news:ia3bqd$ktb$1@news.eternal-september.org...
>>
>> Peter Wensberg, a vice-president at Polaroid, reported that Dr Land ran
>> the
>> entire book of color-perception charts past him, and said he was the first
>> person he'd met who failed every one. Whether this meant Mr Wensberg could
>> not see color at all, I don't know. But he couldn't /distinguish/ them
>> very
>> well.
>>
>> A co-worker once asked me to help with selecting colors for a page he was
>> designing. It turned out he had red-green problems. I showed him a
>> fluorescent-green pen. "What color does that look like to you?" "Orange".
>> I
>> don't know what "orange" looked like to him, but he couldn't distinguish
>> that green from orange.
>>
>
>
>I have an hypothesis that I wish there were a way to explore. Whereas a
>given color of light (or what we call a color) is a definate wavelength, and
>therefore a constant.... BUT.. is human perception of colors universal? ie
>we know when we are seeing "red" (~650nm) because that's what we LEARNED to
>call the color we see as red. Does this necessarily mean that we are all
>perceiving the same hue, or do we each see something a bit different, but we
>all call it the same thing?
>
>As a totally out of the park example: let's say you and your friend are
>looking at a stopsign. You both know that the sign is "red". But perhaps
>what you see is more of an orange, whilst your friend sees something more
>like yellow. As a subjective appearance, the difference in color perception
>would be "normal" to the viewer, whereas were the two of you to "swap"
>perceptions, the world around you would look quite strange.
>
>It may sound like a very offbeat idea, but when you think about it, most
>sensors have a skew in one direction or another: no two cameras register
>color exactly the same.
>
>Just another strange thought to ponder.. :)

Not only possible but likely. The front-end sensors, the cone cells, can
differ slightly between individuals in the concentration and molecular
structure of the photo-pigments that trigger the cell to fire when a
photon is absorbed, resulting in slightly different response curves.

Even cooler -- most birds, as well as some other critters, have a
distinct fourth color receptor.

--
Rich Webb Norfolk, VA

== 5 of 12 ==
Date: Mon, Oct 25 2010 5:43 am
From: "Brenda Ann"

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:ia3ssb$5f1$1@news.eternal-september.org...
>> I have an hypothesis that I wish there were a way to explore. Whereas a
>> given color of light (or what we call a color) is a definate wavelength,
> and
>> therefore a constant... BUT... is human perception of colors universal?
>> ie
>> we know when we are seeing "red" (~650nm) because that's what we
>> LEARNED to call the color we see as red. Does this necessarily mean
>> that we are all perceiving the same hue, or do we each see something
>> a bit different, but we all call it the same thing?
>
> It would be very odd if what I call "blue" looks like what you would call
> "red", as most human beings are chemically and neurologically essentially
> identical.
>
> However, I noticed many years ago that my eyes differ slightly. One has a
> (very) slightly "cooler" or "bluer" balance. Why, I don't know.
>

In theory, yes. In fact, most likely not. There are variations in our other
senses that are much easier to quantify, for example, pain thresholds and
scent thresholds, as well as variations in perception of audio due to ear
shape, etc.

The example, though, was meant to amplify and clarify the idea, rather than
necessarily as a solid example. A difference in perception might be more
subtle, like the difference between burgundy and crimson, or such.

== 6 of 12 ==
Date: Mon, Oct 25 2010 5:51 am
From: Meat Plow

On Sun, 24 Oct 2010 13:30:20 -0500, Jeffrey Angus wrote:

> On 10/24/2010 1:23 PM, Meat Plow wrote:
>> On Sun, 24 Oct 2010 10:54:24 -0700, William Sommerwerck wrote:
>>
>>>> http://tinyurl.com/2eqh6vp
>>>> GE hybrid CFL :)
>>>
>>> Bad, bad idea. That halogen bulb is not going to last very long.
>>
>> Who asked you?
>
> You don't have to ask him, just put anything out where he can find it.
>
> As to the hybrid lamp, probably a good idea if it was designed as a
> "transition" to give light while a slower (more efficient?) CFL comes up
> to full brilliance.
>
> Otherwise it may just be another product for a need we never knew we
> had.
>
> Jeff

Yes it's a transition thing. Halogen immediately and then supposedly a
smooth transition to CFL. I would assume if designed correctly and decent
quality parts used that it should suffer no quicker death than a
traditional CFL.

--
Live Fast, Die Young and Leave a Pretty Corpse

== 7 of 12 ==
Date: Mon, Oct 25 2010 5:56 am
From: Jeffrey Angus

On 10/25/2010 7:18 AM, Rich Webb wrote:
> Even cooler -- most birds, as well as some other critters, have a
> distinct fourth color receptor.
>

Oddly enough, they can see magnetic lines of force.
<http://news.nationalgeographic.com/news/2007/09/070927-magnetic-birds.html>

Jeff

== 8 of 12 ==
Date: Mon, Oct 25 2010 6:02 am
From: Meat Plow

On Sun, 24 Oct 2010 21:14:32 -0700, Jeff Liebermann wrote:

> 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.

I've seen two office refrigerators end up in the trash because
secretaries thought they could use letter openers and a hammer to
carefully break the ice up. Why doesn't your unit have a timed defrost on
it like most home units do?

--
Live Fast, Die Young and Leave a Pretty Corpse

== 9 of 12 ==
Date: Mon, Oct 25 2010 6:26 am
From: Bruce Esquibel

Arfa Daily <arfa.daily@ntlworld.com> 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 :-(

I didn't read every message in this thread so sorry if this has been brought
up already...

<http://www.engadget.com/2010/10/21/ge-introduces-hybrid-bulb-with-both-halogen-and-cfl-elements/>

Look like others share in your observation with startup times.

-bruce
bje@ripco.com

== 10 of 12 ==
Date: Mon, Oct 25 2010 6:25 am
From: Tim Schwartz

On 10/23/2010 9:28 PM, 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

Hello all,

I have certainly observed issues with color spectrum and actual life
vs. claimed life on these lams, as many of you have already noted.

I've also notice that there is a huge variation in turn on
characteristics and color, so unlike traditional filament lamps, which
are pretty consistent from brand to brand, there is a huge variation in
the CFL's

What no one here seemed to mention is the fall off of light output from
the CFL's as they age. I've noticed that if you want the claimed light
output from these, you probably need to replace them every 750-100 hours
or so, again with a huge variation from model to model. A Philips lamp
catalog I once looked at failed to list the light output at the end of
the rated bulb life, something that was listed for virtually every other
type of lamp in the catalog.

I find the CFL's a poor choice in an area where I'm going to read or
work, but just fine in hallways where you just don't want to walk into
things. I was quite surprised when one CFL failed after a year (likely
2000 hours in my application and I replaced it with an identical lamp
form the same package and noted the HUGE difference in brightness.

I feel that the quoted lumens of the CFL's is for a 'young' bulb and
that the fall off is quite rapid. If I had to take a guess on my
hallway light, I would say that at 2000 hours the lamp was down to 40%
of its original output.

I have been using LED lamps in some 'high hat' (PAR30 flood light)
applications in my home. Expensive but worth it.

Regards,
Tim Schwartz
Bristol Electronics

== 11 of 12 ==
Date: Mon, Oct 25 2010 7:10 am
From: "Geoffrey S. Mendelson"

Tim Schwartz wrote:
> I feel that the quoted lumens of the CFL's is for a 'young' bulb and
> that the fall off is quite rapid. If I had to take a guess on my
> hallway light, I would say that at 2000 hours the lamp was down to 40%
> of its original output.

You might think that, but in many cases you would be wrong. When I recently
replaced a year old Osram brand CFL with another of the same wattage, I
noticed immediately it was much brighter.

Then I looked at the old lamp and the box for the new one. The old one was
rated 2/3s of the lumens of the new one.

So in this case, and will all of the osram lamps we bought that day (we bought
several in different sizes and wattages) they were much brighter by design than
the ones just a year old.

What I want to see is a long necked refrigerator bulb. :-)

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
To help restaurants, as part of the "stimulus package", everyone must order
dessert. As part of the socialized health plan, you are forbidden to eat it. :-)

== 12 of 12 ==
Date: Mon, Oct 25 2010 7:25 am
From: "N_Cook"

GE dumping CFLs in the UK.? Supermarket and separately a hardware barn with
GE 11W and 15W CFL at 10 pence (<>15 cents ) each. So broke into a 15W one
240V, 144 mA
FLE15TBXT3/827 10Y
PbF desolders easy enough on the bayonet buttons.
This time 3.3uF , 400V, 105 deg C and 2x BU103A so whatever current rating
of BU102 the BU103A is likely 33 percent higher, still TO92. Much same else
inc 32V diac

==============================================================================
TOPIC: Sometimes, a sledge - hammer is the right tool ... :-)
http://groups.google.com/group/sci.electronics.repair/t/2bc7695b4fb03244?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Oct 25 2010 2:19 am
From: JW

On Fri, 22 Oct 2010 11:04:39 -0400 "Wild_Bill"
<wb_wildbill@XSPAMyahoo.com> wrote in Message id:
<fKhwo.267598$Qg.254816@en-nntp-04.dc1.easynews.com>:

>An instrument designed for this type of troubleshooting is a milli-ohm
>meter, with a 4-wire test probe set and an audio generator that changes the
>pitch of the tone (from the internal speaker), as the very small changes in
>resistance are detected while probing around the board.
>The speaker tone allows the operator to focus attention on the test points,
>and not need to read the digital display constantly.
>
>ToneOhm is a common term associated withh these type of testers, although it
>may be a tradename used by Polar.
>
>http://www.polarinstruments.com/
>navigate: Products to Toneohm 950
>
>There have been many of the older, basic Polar models in the used instrument
>(and eBay) market.
>
>The very basic model I bought (very inexpensivly on eBay) years ago wasn't a
>Polar, made in Britain instead, but I forget the manufacturer's name.
>
>A basic instrument will have a couple of selectors for resolution and tone
>on/off.
>
>Basic milliohm tester-type circuits can be found online.

Yeah, I have a Toneohm 850A at work, but IMO they were too expensive for a
single purpose such as that on my home bench. They're nice because you can
use your ears to track and not have to keep looking up. The resolution is
still only 100 micro ohms, though, same as the HP 3478A I mentioned.

==============================================================================
TOPIC: Type name for a small USB connector?
http://groups.google.com/group/sci.electronics.repair/t/b477c938a7779417?hl=en
==============================================================================

== 1 of 5 ==
Date: Mon, Oct 25 2010 3:08 am
From: "N_Cook"

Smaller than the smallest USB connector I've seen up to now, on compact
cameras etc.
The connector must pass through 5.8 x 3mm hole in casing. Not trapezoid in
cross-section, but rectangular with 2 chamfered corners on a long side

== 2 of 5 ==
Date: Mon, Oct 25 2010 3:17 am
From: "William Sommerwerck"

Is this of any use?

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

How about this?

http://www.cypressindustries.com/products/usb.html

I found all of this in a few seconds.

== 3 of 5 ==
Date: Mon, Oct 25 2010 4:58 am
From: "Wild_Bill"

William S has provided a couple of sources showing different types of USB
connectors.
If you want better quality than just generic, selecting connectors produced
by HRS - Hirose, will generally insure that you get a quality connector.

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

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:ia3kuk$pot$1@news.eternal-september.org...
> Smaller than the smallest USB connector I've seen up to now, on compact
> cameras etc.
> The connector must pass through 5.8 x 3mm hole in casing. Not trapezoid in
> cross-section, but rectangular with 2 chamfered corners on a long side
>
>

== 4 of 5 ==
Date: Mon, Oct 25 2010 5:55 am
From: Meat Plow

On Mon, 25 Oct 2010 11:08:02 +0100, N_Cook wrote:

> Smaller than the smallest USB connector I've seen up to now, on compact
> cameras etc.
> The connector must pass through 5.8 x 3mm hole in casing. Not trapezoid
> in cross-section, but rectangular with 2 chamfered corners on a long
> side

Appears by description a mini 6 pin USB cable. My Casio EX-Z1050 uses
one.

--
Live Fast, Die Young and Leave a Pretty Corpse

== 5 of 5 ==
Date: Mon, Oct 25 2010 7:34 am
From: "N_Cook"

Meat Plow <mhywatt@yahoo.com> wrote in message
news:pan.2010.10.25.12.54.08@lmao.lol.lol...
> On Mon, 25 Oct 2010 11:08:02 +0100, N_Cook wrote:
>
> > Smaller than the smallest USB connector I've seen up to now, on compact
> > cameras etc.
> > The connector must pass through 5.8 x 3mm hole in casing. Not trapezoid
> > in cross-section, but rectangular with 2 chamfered corners on a long
> > side
>
> Appears by description a mini 6 pin USB cable. My Casio EX-Z1050 uses
> one.
>
>
>
> --
> Live Fast, Die Young and Leave a Pretty Corpse

As recessed in its difficult to see as so small , perhaps 8 ruts with 5 or 6
conductors. But smaller than the USB mini AB type. Under 30x as end on can
read 2.2 for the electrical type of USB but still not found a generic name

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

== 1 of 1 ==
Date: Mon, Oct 25 2010 4:54 am
From: "Wild_Bill"

I don't know how you can remove it, and you haven't mentioned what year/type
of car, or manufacturer of the wiper motor, so I doubt anyone else will know
either.

I've found that a high brightness LED on the back side of the board (pointed
straight at the board) is a fairly good way of detecting cracks in PCB
materials.

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

"Vacillator" <user132384@aol.com> wrote in message
news:24fbfbe3-ff71-4464-993c-d9c6110cbdad@u10g2000yqk.googlegroups.com...
> 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: OT: Is this question too challenging for a BSEE graduate?
http://groups.google.com/group/sci.electronics.repair/t/31ba2b6a402a3720?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Oct 25 2010 5:27 am
From: John Fields

On Sun, 24 Oct 2010 18:48:08 -0700, David Nebenzahl
<nobody@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.
>
>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.

---
If you think about a comparator as being nothing more than an opamp
with a huge amount of gain operating open-loop, then for its output to
swing to either rail requires an almost _insignificant_ difference in
voltage between its inputs.

Here: (View in Courier)

+10V
|
|U1
Vin+>-------|+\
| >--Vout
Vin->-------|-/
|
|
-10V

Let's say U1 is an ideal opamp with a gain of one million and that if
Vin+ goes more positive than Vin-, Vout will rise toward +10V, and if
it goes more negative than Vin-, Vout will fall toward -10V.

Now, if Vin+ = Vin-, Vout will sit between the rails at 0V, but since
U1 has a gain of one million and we have a +10V rail, all it'll take
for the output to rise to the positive rail is for Vin+ to be 10
microvolts (or more) more positive than Vin-.

Conversely, all it'll take for Vout to fall to the negative rail is
for Vin+ to be >=10µV more negative than Vin-.

Also, it's important to realize that it doesn't matter what voltage
Vin+ and Vin- are sitting at, what matters is the difference between
them.

>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.

---
Correct.
---

>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?

---
Yes
---

>If so, how does that work?

---
Consider, first, the magical voltage divider: ;)

E1
|
[R1]
|
+---E2
|
[R2]
|
GND

Where, if GND is at 0V,

E1 * R2
E2 = ---------
R1 + R2

Just for grins, let's set this up:

10V E1V
|
[9k] R1
|
+---E2
|
[1k] R2
|
GND

and solve for E2:

10V * 1kR
E2 = ----------- = 1V
9kR + 1kR

Next, let's hook up the the voltage divider to an opamp in the
non-inverting configuration and apply 1V to the + input to see what'll
happen:

+V
|
1V>-------|+\
| >--+-- E1
+--|-/ |
| | [9k] R1
| -V |
+--------+-->E2
|
[1k] R2
|
gnd

Now, since the + input is sitting at 1V, the output will have to move
with sufficient magnitude and in the proper direction to make the
voltage on the - input equal to the voltage on the + input.

Since the + input is at +1V, the output will have to swing positive,
and for E2 to to get to +1V, we'll rearrange the voltage divider
equation to solve for E2, and we'll get:

E2R1 + E2R2 (1V * 9kR) + (1V * 1kR)
E1 = ------------- = ------------------------- = 10V
R2 1kR

So there you have it: a non-inverting opamp with its gain of one
million throttled down to 10. :-)

To adjust the gain, then, all that's necessary is to adjust the ratio
R1:R2 and the output will go wherever it has to in order to make the
inputs of the opamp equal to each other.

The gain of the circuit can be described as, simply,:

R1 + R2
Av = ---------
R2
---

>This still sounds rather mysterious to me.

---
Even now? ;)

---
JF

==============================================================================
TOPIC: Whirlpool RF0100 electric stove trips breaker.
http://groups.google.com/group/sci.electronics.repair/t/88c59b94b9023959?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Oct 25 2010 5:29 am
From: "Wild_Bill"

I should've been paying more attention when I read the part about you using
the PR57 leakage test.
I wasn't picturing/visualizing that the armor sheaths of the heating
elements could or would be in direct electrical contact with the oven
cabinet. I'd been assuming that insulators were in place to isolate them.

I suspect that if the element were removed and the leakage test was applied
to the element, the meter would confirm internal leakage in the element, and
possibly other leakage paths in one or more of the other elements.

The Sencore Zmeters have leakage tests (up to 1kV), as do numerous other
instruments.

Leakage testing can be utilized for many types of electrical and electronic
devices, from full appliances, motors, and other large components, to
transformers and small semiconductor devices.
Megohm meters and Hi-Pot testing equipment/instruments are typically used
for line voltage operated machines, appliances and power transformers for
safety requirements, but also for troubleshooting.

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

"David Farber" <farberbear.unspam@aol.com> wrote in message
news:i9se9v$r9d$1@news.eternal-september.org...
>
> Here's the way I see it. Starting from L1, current flows through the limit
> switch then to the thermostat. If the thermostat switch is turned on by
> the thermocouple, then the current continues on to the bake element and
> then the circuit is completed when it connects to L2, which is where the
> neutral line is. I don't see any connection to that and the metal cabinet
> parts. So either my analysis is wrong or there is current leaking to
> ground.
>
> Just so there is no confusion, from left to right in the schematic, the
> original 240V wiring of L1, N, L2 has been changed to 120V wiring of,
> Line, Ground, and N. I can remove the bonding strap which connects the
> chassis to N in the 240V schematic or Ground in the 120V version that I
> came up with. I'd just like to understand what's going on here.
>
> Thanks for your reply.
> --
> David Farber
> Los Osos, CA
>

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

== 1 of 1 ==
Date: Mon, Oct 25 2010 5:44 am
From: PeterD

On Sun, 24 Oct 2010 20:43:14 -0700, "John Fields"
<jfields@austininstruments.com> wrote:

>...
>X-Usenet-Provider: http://www.giganews.com
>NNTP-Posting-Host: 66.53.27.94
>...
>JF

The NNTP-Posting-Host is one major clue (there are many others) and
one quickly sees the differences. For example, when a known good
person starts making replies that are out of character, what we do is
compare a known valid post with the one that is suspect. We
immediately see what's what, and then can quickly eliminate the person
who is trying (poorly) to impersonate us (yes, us, as he has
impersonated me, and about 10 others here...)

But if you are an infrequent user of these groups, I can see where you
can get confused as to who is who. No problem...

An addition to my earlier reply... I'd suggest if you can, use a power
meter (say a Kill-A-Watt device) and measure each unit you are
intersted in. I tend to not trust manufacturer's claims on stuff like
that. Some tend to be way off, and some update and make more effecient
products over time but don't update documentation and labels until
well after the units are in production!

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