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Today's topics:

* (paypal payment) wholesale 2010 New fashio brand name goods - 1 messages, 1
author
http://groups.google.com/group/sci.electronics.repair/t/26f4bbdf064773b6?hl=en
* OT: Is this question too challenging for a BSEE graduate? - 5 messages, 4
authors
http://groups.google.com/group/sci.electronics.repair/t/31ba2b6a402a3720?hl=en
* Type name for a small USB connector? - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/b477c938a7779417?hl=en
* THE TRUTH TO MAKING $13,693.94 IN 48 HOURS - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/d0869fc7ca3cdc07?hl=en
* PENELOPE CRUZ Latest Scandals Revealed - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/a81f2abea4239671?hl=en
* Another reason to hate CFLs ... - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/87ea27a2579f0316?hl=en

==============================================================================
TOPIC: (paypal payment) wholesale 2010 New fashio brand name goods
http://groups.google.com/group/sci.electronics.repair/t/26f4bbdf064773b6?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Oct 25 2010 8:00 pm
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==============================================================================
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 5 ==
Date: Mon, Oct 25 2010 8:09 pm
From: Spehro Pefhany

"krw@att.bizzzzzzzzzzzz" <krw@att.bizzzzzzzzzzzz> wrote in
news:mv9cc6pn3fclvj5k6certg2e1mj443p3d8@4ax.com:

> On Mon, 25 Oct 2010 00:43:24 -0700, "William Sommerwerck"
> <grizzledgeezer@comcast.net> wrote:
>
>>>> 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.
>>
>>No, it's fact. It is, as I said, /the/ fundamental principle of op-amp
>>circuit design.
>
> One of three principles:
>
> 1: Gain is infinite Vout/((V+) - (V-)) = infinity
> 2: Input impedance is infinite
> 3: Output impedance is zero
>

4: Phase shift is zero at all frequencies

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info : http://www.speff.com

== 2 of 5 ==
Date: Mon, Oct 25 2010 8:12 pm
From: Spehro Pefhany

"krw@att.bizzzzzzzzzzzz" <krw@att.bizzzzzzzzzzzz> wrote in
news:25acc616cisme9t9pgb37aojp1vv4r88fa@4ax.com:

> 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.
>>
>>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 difference between an opamp and comparitor is that the comparitor
> is designed to be operated with its output burried in the rails (some
> don't have a current sourcing capability, either). Comparitors can be
> made out of most opamps but they're generally pretty slow because they
> don't like their outputs saturated.

A comparator also designed to operate with a significant voltage between
the inputs. Many modern op-amps will allow significant current to flow
if there is more than a diode drop or so between the inputs. At least
one older op-amp would exhibit Vos drift over time in the presence of
continous voltage between the inputs.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info : http://www.speff.com

== 3 of 5 ==
Date: Mon, Oct 25 2010 8:44 pm
From: isw

In article <ia3ced$no0$1@news.eternal-september.org>,
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

> >> 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.
>
> No, it's fact. It is, as I said, /the/ fundamental principle of op-amp
> circuit design.
>
> I can't think of a book that discusses this in a fairly simple way. Even the
> Philbrick book -- which is hard to find these days -- doesn't address the
> matter as directly as I'd like. But, trust me. Most op-amp circuits can be
> analyzed by assuming the voltage is the same, then applying simple circuit
> analysis. You might start with the basic op-amp inverting amplifier, and see
> what happens.

Actually, you can do it with bipolar transistor circuits too, to a first
approximation:

Base => inverting input
Emitter => non-inverting input
Collector => output

Of course, the two inputs have rather different impedances, but for
figuring out gains and so on, it works pretty well.

Isaac

== 4 of 5 ==
Date: Mon, Oct 25 2010 10:37 pm
From: ehsjr

David Nebenzahl 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.
>
> 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.
>
>

I think you might be missing the fact that the circuit has feedback,
from the output to the inverting input. Take a look at the schematic
again.

The op amp "sees" a voltage on the + input and does whatever it can
to make the - input the same voltage. The output of the op amp is
connected back to the - input, so when the op amp raises or lowers
the voltage on the output pin, that voltage appears on the - input.
Thus, if you put X volts on the non-inverting (+) input, you'll get
X volts on the inverting (-) input.

Ed

== 5 of 5 ==
Date: Mon, Oct 25 2010 11:09 pm
From: David Nebenzahl

On 10/25/2010 10:37 PM ehsjr spake thus:

> I think you might be missing the fact that the circuit has feedback,
> from the output to the inverting input. Take a look at the schematic
> again.
>
> The op amp "sees" a voltage on the + input and does whatever it can
> to make the - input the same voltage. The output of the op amp is
> connected back to the - input, so when the op amp raises or lowers
> the voltage on the output pin, that voltage appears on the - input.
> Thus, if you put X volts on the non-inverting (+) input, you'll get
> X volts on the inverting (-) input.

Now that I understand things a little better, yes, I do get the feedback
here, and in other op amp circuits.

But just a small quibble with the way you and others have described
what's going on here. You say "the op amp ... does whatever it can to
make the - input the same voltage" (as the + input). In fact, it does no
such thing: the input is, after all, just an input.

What you might ought have said is that the *circuit*, including the
feedback loop, forces the inverting input to (virtually) the same
voltage as the noninverting input, right? The op amp, in and of itself,
doesn't "do" anything to (that is, out of) either input. It's only by
virtue of the feedback that this action occurs.

Maybe just a semantic quibble. Other than that I'm with you here. Thanks
to all for explaining.

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

== 1 of 3 ==
Date: Mon, Oct 25 2010 8:52 pm
From: isw

In article <ia3kuk$pot$1@news.eternal-september.org>,
"N_Cook" <diverse@tcp.co.uk> 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

Although those connectors may carry USB signals, I think they're not
always "USB connectors"; some of the ones on cameras also carry
audio/video signals, and they don't mate with similar-appearing USB
connectors.

Isaac

== 2 of 3 ==
Date: Tues, Oct 26 2010 12:05 am
From: "N_Cook"

isw <isw@witzend.com> wrote in message
news:isw-799CC6.20523725102010@[216.168.3.50]...
> In article <ia3kuk$pot$1@news.eternal-september.org>,
> "N_Cook" <diverse@tcp.co.uk> 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
>
> Although those connectors may carry USB signals, I think they're not
> always "USB connectors"; some of the ones on cameras also carry
> audio/video signals, and they don't mate with similar-appearing USB
> connectors.
>
> Isaac

That makes sense but there is a standard USB symbol at this camera connector

== 3 of 3 ==
Date: Tues, Oct 26 2010 12:24 am
From: "N_Cook"

whit3rd <whit3rd@gmail.com> wrote in message
news:a491ecd9-4a30-4a19-a3a4-7408a0396d66@a37g2000yqi.googlegroups.com...
On Oct 25, 3:08 am, "N_Cook" <dive...@tcp.co.uk> 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

My Konica/Minolta DiMage E 500 camera uses such a connector. The tip
measures 0.082" by 0.193", about 2.1mm by 4.9 mm.
It has five gold fingers (probably two are power-ground) with
asymmetric placement (1 x x x 1 1 1 1 ).

As for a name, or vendor, I dunno.

*********
Sounds like the critter
I'll go with the name micro USB . But thinking about it later, I'm currently
removing the SD card and reading via a different camera and larger USB. Long
term reliability of repeatedly using the large SD contacts must be better
than using this micro USB with contacts that are so fine they are on the
point of non-resolability of my eyesight.

==============================================================================
TOPIC: THE TRUTH TO MAKING $13,693.94 IN 48 HOURS
http://groups.google.com/group/sci.electronics.repair/t/d0869fc7ca3cdc07?hl=en
==============================================================================

== 1 of 2 ==
Date: Mon, Oct 25 2010 9:27 pm
From: superman

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== 2 of 2 ==
Date: Mon, Oct 25 2010 10:46 pm
From: Jeffrey Angus

On 10/25/2010 11:27 PM, superman wrote:
> THE TRUTH TO MAKING $13,693.94 IN 48 HOURS

Spam as many news groups as you can, and cash the checks
then run for your life before "they" catch up with you
and beat you to death.

Jeff

==============================================================================
TOPIC: PENELOPE CRUZ Latest Scandals Revealed
http://groups.google.com/group/sci.electronics.repair/t/a81f2abea4239671?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Oct 26 2010 12:27 am
From: nasq

Some Security Reasons I have Hidden the Videos ...... CLICK on the
IMAGE below the SEARCH BOX for videos http://www.actressgossip.c0m.st

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

== 1 of 1 ==
Date: Tues, Oct 26 2010 12:39 am
From: "N_Cook"

Jeff Liebermann <jeffl@cruzio.com> wrote in message
news:8no8c6pc1ep3atfd6fv2rt37t0of39ti7r@4ax.com...
> On Sun, 24 Oct 2010 09:50:24 +0100, "N_Cook" <diverse@tcp.co.uk>
> wrote:
>
> >These days fibre reinforced plastic or mineralised plastic, used to be
> >ceramic in the original ones,
>
> Reinforced Polybutylene Terephthalate (PBT) or Polyethylene
> Terephthalate (PET) plastic resin with about 30% glass fiber mixed in
> to minimally meet UL-94 V-0 flame retartent specs.
>
> MSDS for CFL from Home Despot:
>
<http://www.homedepot.com/catalog/pdfImages/fd/fd8f96e1-4ff3-4a86-9070-e8583
d3e636e.pdf>
>
> >Googling for BU102 + TO92 gets nowhere, I
> >assume as diac in there then triacs
>
> What's inside and how it works:
> "Self Oscillating 25W CFL Lamp Circuit"
> <http://www.nxp.com/documents/application_note/AN00048.pdf>
>
> Fiat Lux
> (let there be light).
>
> --
> 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

Returning to that Philips application note
I can only find SOT533 version of BUJ101AU, eg
http://www.datasheetcatalog.org/datasheet/philips/BUJ101AU.pdf
a power transistor format rather than TO92 format with 1.5A/3A : 400V/700V
rating , perhaps for this specific use and known peak/av duty cycle then
could be packaged in TO92

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