sci.electronics.repair@googlegroups.com

Today's topics:

* Roland XP 60 , 5 octave keyboard , 1997 - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/3078908fbe1e3ff8?hl=en
* Batteries That Do Not Leak w/Age? - 3 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/fd55784ea36aafe5?hl=en
* RAC Portable Power Station, need DC adaptor spec - 5 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/b105b15b5ad9d933?hl=en
* Emachines Motherboard Failure Loss Of Onboard Video No Startup T3410 Desktop
PC - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/89c065f832dd79ec?hl=en
* looking for DAQ that measures PPM tia sal22 - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/8f7517bc0bc14e6f?hl=en
* low cost thermocouple DAQ that works with ubuntu linux tia sal22 - 5
messages, 5 authors
http://groups.google.com/group/sci.electronics.repair/t/6df4cca829179f26?hl=en
* discount sale air jordan shoes (www.nike-black.com) - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/981507dcb91c66c8?hl=en
* 100v--> 10V Trans. on 120V - 5 messages, 5 authors
http://groups.google.com/group/sci.electronics.repair/t/c8528fdeff78820d?hl=en
* Sony KV27EXR20 Sound no picture - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/41a66d907546cb08?hl=en
* PS/2-to-AT keyboard adapter - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/d8e9826e9e554abf?hl=en

==============================================================================
TOPIC: Roland XP 60 , 5 octave keyboard , 1997
http://groups.google.com/group/sci.electronics.repair/t/3078908fbe1e3ff8?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 3 2010 12:39 am
From: "N_Cook"

1.44MB on this XP 60

==============================================================================
TOPIC: Batteries That Do Not Leak w/Age?
http://groups.google.com/group/sci.electronics.repair/t/fd55784ea36aafe5?hl=en
==============================================================================

== 1 of 3 ==
Date: Fri, Dec 3 2010 4:31 am
From: Bob Villa

On Dec 3, 1:28 am, "Wild_Bill" <wb_wildb...@XSPAMyahoo.com> wrote:
> I fully agree with your demonstration of trimming, which I had also done and
> explained, however it was snipped.
>
> You and I could describe and demonstrate trimming endlessly, and it won't
> convince the typical usenet user to trim posts before sending them.
> The majority are just too lazy and/or inconsiderate, which no amount of
> exchanges will change.
>
> --
> Cheers,
> WB
> .............
>
> "David Nebenzahl" <nob...@but.us.chickens> wrote in message
>
> news:4cf8699d$0$2409$822641b3@news.adtechcomputers.com...
>
>  Duh.

Netiquette says "top posting" is rude! IRMC

== 2 of 3 ==
Date: Fri, Dec 3 2010 7:04 am
From: "(PeteCresswell)"

Per Wild_Bill:
>Bottom posting isn't sensible, or I would have been doing it for the last
>12-14 years.
>So you see, this is my conventional method.

+1.

I bottom post because that seems tb what most people want.

But it seems to me like a holdover from the character/line-based
days where one could not easily jump pack to previous articles.

Given a choice between reading top-posted replies and
bottom-posted replies with indiscriminate quoting, I'll take the
top-posted replies any day. The ability to turn quotes on/off
mitigates bottom posting somewhat, but it's still more work to
read.

The ideal would seem tb inserting reply text under the relevant
quoted material and not quoting the whole history of the thread.
--
PeteCresswell

== 3 of 3 ==
Date: Fri, Dec 3 2010 10:01 am
From: David Nebenzahl

On 12/3/2010 7:04 AM (PeteCresswell) spake thus:

> Per Wild_Bill:
>
>> Bottom posting isn't sensible, or I would have been doing it for
>> the last 12-14 years. So you see, this is my conventional method.
>
> +1.
>
> I bottom post because that seems tb what most people want.
>
> But it seems to me like a holdover from the character/line-based
> days where one could not easily jump pack to previous articles.
>
> Given a choice between reading top-posted replies and
> bottom-posted replies with indiscriminate quoting, I'll take the
> top-posted replies any day. The ability to turn quotes on/off
> mitigates bottom posting somewhat, but it's still more work to
> read.
>
> The ideal would seem tb inserting reply text under the relevant
> quoted material and not quoting the whole history of the thread.

Further confirmation that good posting style depends on more than just
bottom (or inter-) posting. Judicious trimming is a crucial part of it.
Not just lazily tacking your 2-line reply to the bottom of a 200-line
collection of previous posts and replies.

And yes, if one has multiple responses to a post, then posting the
replies directly under the relevant material is the way to go, as most
people seem to do here.

--
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: RAC Portable Power Station, need DC adaptor spec
http://groups.google.com/group/sci.electronics.repair/t/b105b15b5ad9d933?hl=en
==============================================================================

== 1 of 5 ==
Date: Fri, Dec 3 2010 5:01 am
From: Terry Fields

Dave Plowman (News) wrote:

>In article <nlqff6le70eicehuhjv66q20eo6vjngq2o@4ax.com>,
> Terry Fields <no.spam.here@thanks.invalid> wrote:
>
>> These days battery chargers are very sophisticated things in how they
>> treat batteries. If your friend has more than one battery to care for,
>> an Optimate or Accumate charger might be a good idea, but they aren't
>> cheap.
>
>No need to pay silly prices for a sophisticated battery charger. Lidl and
>Aldi in the UK both do similar ones for about 14 gbp. They pulse charge a
>flat battery, change to a normal charge, then switch to a maintenance one.
>Get the same thing with a 'name' on it and you'll pay four times as much.

As the battery in the appliance seemed to be a SLA, getting maximum
life out of it demands using an appropriate charger rather than a
random wall-wart. I use an Accumate to keep both a SLA and a
motorcycle battery in good order - I don't have any experience of the
Lidl or Aldi chargers.

TF

== 2 of 5 ==
Date: Fri, Dec 3 2010 5:54 am
From: "Dave Plowman (News)"

In article <hgkhf6lkfti0ln71929nanqg98dlue9en5@4ax.com>,
Terry Fields <no.spam.here@thanks.invalid> wrote:
> >No need to pay silly prices for a sophisticated battery charger. Lidl
> >and Aldi in the UK both do similar ones for about 14 gbp. They pulse
> >charge a flat battery, change to a normal charge, then switch to a
> >maintenance one. Get the same thing with a 'name' on it and you'll pay
> >four times as much.

> As the battery in the appliance seemed to be a SLA, getting maximum life
> out of it demands using an appropriate charger rather than a random
> wall-wart.

Of course. True SLA (gel) should be charged at constant voltage. They're
not so tolerant as car batteries in this respect.

> I use an Accumate to keep both a SLA and a motorcycle battery
> in good order - I don't have any experience of the Lidl or Aldi chargers.

These things tend to have different brand names depending on who sells
them - but most are simply a wall wart with a few pennies of extra
components. Usually not worth the premium price.

--
*I have a degree in liberal arts -- do you want fries with that

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

== 3 of 5 ==
Date: Fri, Dec 3 2010 9:06 am
From: robgraham

On Dec 3, 12:07 am, "Dave Plowman (News)" <d...@davenoise.co.uk>
wrote:
> In article <nlqff6le70eicehuhjv66q20eo6vjng...@4ax.com>,
>    Terry Fields <no.spam.h...@thanks.invalid> wrote:
>
> > These days battery chargers are very sophisticated things in how they
> > treat batteries. If your friend has more than one battery to care for,
> > an Optimate or Accumate charger might be a good idea, but they aren't
> > cheap.
>
> No need to pay silly prices for a sophisticated battery charger. Lidl and
> Aldi in the UK both do similar ones for about 14 gbp. They pulse charge a
> flat battery, change to a normal charge, then switch to a maintenance one.
> Get the same thing with a 'name' on it and you'll pay four times as much.
>
> --
> *They call it PMS because Mad Cow Disease was already taken.  
>
>     Dave Plowman        d...@davenoise.co.uk           London SW
>                   To e-mail, change noise into sound.

The Lidl /Aldi offerings are good there is no doubt, but they are
never there when you want them !! You have to be on their mailing
list and make a judgement to buy when they are available - and then
they sit around for ages ..... until that magic moment and hey presto
they do the job. Just been there this afternoon to top up a spare car
battery just in case, using one of these I bought probably a year
ago. Serious cold now in Edinburgh and I can see some sluggish
starting coming up.

== 4 of 5 ==
Date: Fri, Dec 3 2010 9:17 am
From: "Dave Plowman (News)"

In article
<9156b7f2-2970-4352-96af-72f521cb2e64@a28g2000prb.googlegroups.com>,
robgraham <robkgraham@btinternet.com> wrote:
> > No need to pay silly prices for a sophisticated battery charger. Lidl
> > and Aldi in the UK both do similar ones for about 14 gbp. They pulse
> > charge a flat battery, change to a normal charge, then switch to a
> > maintenance one. Get the same thing with a 'name' on it and you'll pay
> > four times as much.

> The Lidl /Aldi offerings are good there is no doubt, but they are
> never there when you want them !! You have to be on their mailing
> list and make a judgement to buy when they are available - and then
> they sit around for ages ..... until that magic moment and hey presto
> they do the job. Just been there this afternoon to top up a spare car
> battery just in case, using one of these I bought probably a year
> ago. Serious cold now in Edinburgh and I can see some sluggish
> starting coming up.

They're cheap enough to build into the car. I've done this on my
'classic'. With a waterproof mains connector under the rear bumper.

I get emails from both Aldi and Lidl showing their offers of the week.
With some of them you have to get there early.

--
*Certain frogs can be frozen solid, then thawed, and survive *

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

== 5 of 5 ==
Date: Fri, Dec 3 2010 3:48 pm
From:

On 3 Dec,
"Dave Plowman (News)" <dave@davenoise.co.uk> wrote:

> In article <hgkhf6lkfti0ln71929nanqg98dlue9en5@4ax.com>,
> Terry Fields <no.spam.here@thanks.invalid> wrote:
> > >No need to pay silly prices for a sophisticated battery charger. Lidl
> > >and Aldi in the UK both do similar ones for about 14 gbp. They pulse
> > >charge a flat battery, change to a normal charge, then switch to a
> > >maintenance one. Get the same thing with a 'name' on it and you'll pay
> > >four times as much.
>
> > As the battery in the appliance seemed to be a SLA, getting maximum life
> > out of it demands using an appropriate charger rather than a random
> > wall-wart.
>
> Of course. True SLA (gel) should be charged at constant voltage. They're
> not so tolerant as car batteries in this respect.
>
> > I use an Accumate to keep both a SLA and a motorcycle battery
> > in good order - I don't have any experience of the Lidl or Aldi chargers.
>
> These things tend to have different brand names depending on who sells
> them - but most are simply a wall wart with a few pennies of extra
> components. Usually not worth the premium price.
>
My Aldi power station seems to use a basic unstabilised wall wart. However,
it seems to charge up to a reasonable voltage, then cease charging (or go to
a very low current) I've been using it to power some electronics, and I've
been monitoring its voltage. It seems to cut out somewhere between 13.5 and
14 volts.

--
B Thumbs
Change lycos to yahoo to reply

==============================================================================
TOPIC: Emachines Motherboard Failure Loss Of Onboard Video No Startup T3410
Desktop PC
http://groups.google.com/group/sci.electronics.repair/t/89c065f832dd79ec?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 3 2010 5:22 am
From: mike

Wild_Bill wrote:
> I wouldn't think these steps would be possible with the failed m-bd since
> there was no POST or video output, or access to BIOS setup.
>
With no POST then there's not much you can do - it may not make sense
to spend anymore time on the old
board, but I wonder , if you have one of those IR thermometers, if you
can find any caps that are suspiciously warm when the power is applied
to it.

> The new board is operating as it should, but I didn't check to see if the
> drivers and BIOS are the newest versions shown on the Emachine support site.
> The BIOS version shows up briefly after/during POST on older machines, but I
> didn't look for it after the new board was installed.
>
> The old CPU or the m-bd have failed, most likely.. and if I were willing to
> throw more money into it, I could first replace some electrolytic caps that
> have suspiciously high ESR (small 100uF several of 'em, and a couple of
> others), or buy a new CPU.
>
> The larger value caps for the CPU voltages appear to be connected in
> parallel, so the in-circuit ESR readings aren't reliable. Desoldering them
> for testing isn't a big deal, but the board is old and wasn't a high grade
> board when new.
>
I had a fairly reliable Emachines system for several years, but, after
developing bulging caps over a period of months it finally just
refused to start up one day - I hadn't any experience changing out
caps at that time,
kinda wish I'd held onto it, once I'd had a few successes reviving a
few things with new capacitors.

Mike

==============================================================================
TOPIC: looking for DAQ that measures PPM tia sal22
http://groups.google.com/group/sci.electronics.repair/t/8f7517bc0bc14e6f?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Dec 3 2010 5:26 am
From: N0Spam@daqarta.com (Bob Masta)

On Thu, 02 Dec 2010 15:36:33 GMT, ratullloch_delthis
<ratullloch_delthis@gmail.com> wrote:

>Greetings all
>
>I'm looking for a DAQ that will measure PPM (particles per million) over time, can anyone recomend one?
>
>tial sal22
>

Could you elaborate on exactly what you want to do?

Best regards,

Bob Masta

DAQARTA v5.10
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
DaqMusic - FREE MUSIC, Forever!
(Some assembly required)
Science (and fun!) with your sound card!

== 2 of 2 ==
Date: Fri, Dec 3 2010 5:37 am
From: Martin Brown <|||newspam|||@nezumi.demon.co.uk>

On 03/12/2010 13:26, Bob Masta wrote:
> On Thu, 02 Dec 2010 15:36:33 GMT, ratullloch_delthis
> <ratullloch_delthis@gmail.com> wrote:
>
>> Greetings all
>>
>> I'm looking for a DAQ that will measure PPM (particles per million) over time, can anyone recomend one?

Not really clear here what you are asking for.
DACs output voltages, and ADCs measure them.

Old Solatron 7060 voltmeter secondhand, provided you don't want absolute
calibration will just about do it on the 10v range (as will some of the
later models but they are usually more expensive).

It is actually rather hard to get ppm low noise ADCs to behave reliably
at 6 sig figs and you need reference gear to qualify and calibrate it.

Regards,
Martin Brown

==============================================================================
TOPIC: low cost thermocouple DAQ that works with ubuntu linux tia sal22
http://groups.google.com/group/sci.electronics.repair/t/6df4cca829179f26?hl=en
==============================================================================

== 1 of 5 ==
Date: Fri, Dec 3 2010 7:08 am
From: Glen Walpert

On Wed, 01 Dec 2010 20:21:21 -0500, Phil Hobbs wrote:

> Glen Walpert wrote:
>> On Tue, 30 Nov 2010 14:15:28 -0500, Rich Webb wrote:

>>>> Thermocouples are really really horrible temperature sensors--almost
>>>> as bad as ICs. Their advantages are small size, relatively low cost,
>>>> and (potentially) high speed, but their disadvantage is that it's
>>>> really hard to get good measurements.
>>>>
>>>> One reason for this is thermal conduction down the leads (which is a
>>>> big problem for most temperature sensors). There's a worse one,
>>>> though: due to their very low sensitivity, thermocouples are
>>>> extremely vulnerable to errors caused by offset drift in the
>>>> circuitry. See Figure 20.3 on P. 803 at
>>>> http://electrooptical.net/www/book/draftthermal.pdf
>>>
>>> "Thermocouples generate a voltage related to the temperature
>>> difference between two junctions of dissimilar metal wires, and are a
>>> pain in the neck. ... For less specialized applications, avoid
>>> thermocouples like fleas."
>>>
>>> Okay, now I'm going to *have* to buy that book!
>>
>> Yes, that is a good one, and I can't argue with Phil's assessment of TC
>> accuracy, but "You can learn all you ever wanted to know about them
>> from the Omega Engineering catalogue." is true only if you have no
>> interest in how they actually work (as opposed to how to use them) or
>> how to make a really good low drift TC measurement system with accurate
>> CJC and high immunity to EMI, for instance.
>>
>> There are many trade-offs in sensor selection, and thermocouples excel
>> in temperature range and durability as well as (sometimes) speed. A TC
>> can be smashed flat with a hammer and suffer no loss in accuracy until
>> the wires break, or welded to metal parts for excellent thermal contact
>> with the part being measured, for instance. Try that with a thermistor
>> :-).
>>
>>
> You can solder RTDs down, which is about the same thing. And the
> circuit details aren't really information about the _sensor_--any
> sufficiently poor sensor will have those problems.
>
> I've used thermocouples reasonably often, generally running inside an
> evaporator or someplace like that, and attached to a Fluke thermocouple
> thermometer with built-in cold junction compensation. That was probably
> good to a couple of degrees, which was all I really needed, especially
> since I didn't have to replace the TCs, so the measurements correlated
> pretty well over time.

From the perspective of your book - temperature stabilization of electro-
optical components - I agree completely that thermocouples should
generally be avoided like fleas. From my perspective, with a background
in power plant control, thermocouples and RTD's are the rule and
thermistors the rare exception.

What really irks me about Omega is that their "Thermocouple Introduction
and Theory" section is actually a "thermocouple introduction and
completely bogus theory". Correct theory can be found at:
<http://www.electronics-cooling.com/Resources/EC_Articles/JAN97/
jan97_01.htm>

And better yet is another article which I can no longer find on the web,
which I will post on ABSE with thread title "thermocouple theory article"
in case anyone is interested.

Glen

== 2 of 5 ==
Date: Fri, Dec 3 2010 8:01 am
From: Phil Hobbs

Glen Walpert wrote:
> On Wed, 01 Dec 2010 20:21:21 -0500, Phil Hobbs wrote:
>
>> Glen Walpert wrote:
>>> On Tue, 30 Nov 2010 14:15:28 -0500, Rich Webb wrote:
>
>>>>> Thermocouples are really really horrible temperature sensors--almost
>>>>> as bad as ICs. Their advantages are small size, relatively low cost,
>>>>> and (potentially) high speed, but their disadvantage is that it's
>>>>> really hard to get good measurements.
>>>>>
>>>>> One reason for this is thermal conduction down the leads (which is a
>>>>> big problem for most temperature sensors). There's a worse one,
>>>>> though: due to their very low sensitivity, thermocouples are
>>>>> extremely vulnerable to errors caused by offset drift in the
>>>>> circuitry. See Figure 20.3 on P. 803 at
>>>>> http://electrooptical.net/www/book/draftthermal.pdf
>>>>
>>>> "Thermocouples generate a voltage related to the temperature
>>>> difference between two junctions of dissimilar metal wires, and are a
>>>> pain in the neck. ... For less specialized applications, avoid
>>>> thermocouples like fleas."
>>>>
>>>> Okay, now I'm going to *have* to buy that book!
>>>
>>> Yes, that is a good one, and I can't argue with Phil's assessment of TC
>>> accuracy, but "You can learn all you ever wanted to know about them
>>> from the Omega Engineering catalogue." is true only if you have no
>>> interest in how they actually work (as opposed to how to use them) or
>>> how to make a really good low drift TC measurement system with accurate
>>> CJC and high immunity to EMI, for instance.
>>>
>>> There are many trade-offs in sensor selection, and thermocouples excel
>>> in temperature range and durability as well as (sometimes) speed. A TC
>>> can be smashed flat with a hammer and suffer no loss in accuracy until
>>> the wires break, or welded to metal parts for excellent thermal contact
>>> with the part being measured, for instance. Try that with a thermistor
>>> :-).
>>>
>>>
>> You can solder RTDs down, which is about the same thing. And the
>> circuit details aren't really information about the _sensor_--any
>> sufficiently poor sensor will have those problems.
>>
>> I've used thermocouples reasonably often, generally running inside an
>> evaporator or someplace like that, and attached to a Fluke thermocouple
>> thermometer with built-in cold junction compensation. That was probably
>> good to a couple of degrees, which was all I really needed, especially
>> since I didn't have to replace the TCs, so the measurements correlated
>> pretty well over time.
>
> From the perspective of your book - temperature stabilization of electro-
> optical components - I agree completely that thermocouples should
> generally be avoided like fleas. From my perspective, with a background
> in power plant control, thermocouples and RTD's are the rule and
> thermistors the rare exception.
>
> What really irks me about Omega is that their "Thermocouple Introduction
> and Theory" section is actually a "thermocouple introduction and
> completely bogus theory". Correct theory can be found at:
> <http://www.electronics-cooling.com/Resources/EC_Articles/JAN97/
> jan97_01.htm>
>
> And better yet is another article which I can no longer find on the web,
> which I will post on ABSE with thread title "thermocouple theory article"
> in case anyone is interested.
>
> Glen

I'm not too impressed with the Electronics Cooling article. The
thermoelectric effect is treated as magic--the two integrals at the
beginning of the article just integrate the magic along the length of
the wire without explaining anything. There's some useful applications
advice, but there's some pure nonsense, e.g. saying that 20 wire
diameters' worth of lead length is enough to get a good measurement of
gas temperature. The ratio of the wire's thermal conductance (in W/K)
to its surface area goes as diameter/(length**2), so for a given
accuracy, the required lead length goes as the square root of the wire
diameter.

I agree that Omega isn't the best place to look for the actual physics
of thermocouples, but they do have nice pictures. Anyway, that physics
is more or less bottomless...you can stick with classical thermodynamics
and use the grand canonical ensemble, but then you get into actual solid
state physics and have to worry about things like the density of states
differences in different crystal orientations, and then you get into the
real quantum mechanics of disordered systems stuff. As I said,
bottomless, and although I talk a good game, my actual solid state
physics expertise goes about ankle deep. (I did take graduate solid
state from Walt Harrison, who is the biggest wildman in all of
theoretical sold state physics, but didn't pay enough attention. Same
with graduate statistical mechanics.)

I'm not the worst offender, though. A lot of the explanations you hear
about physics have as much merit as the Friday afternoon stock market
guy 'explaining' what happened on Wall Street that week. The idea that
an electret mic is a variety of capacitance mic is one example, and
almost anything mentioning 'surface states' and 'traps' is another.
It's not that traps and surface states don't exist, but they're very
commonly used as a cloak for ignorance--understandably, since real solid
state measurements are hard, and tend to involve ultrahigh vacuum.

All of that said, for instrument purposes delving into the fine details
of thermocouples is putting lipstick on a pig. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

== 3 of 5 ==
Date: Fri, Dec 3 2010 9:59 am
From: George Herold

On Dec 3, 10:08 am, Glen Walpert <nos...@null.void> wrote:
> On Wed, 01 Dec 2010 20:21:21 -0500, Phil Hobbs wrote:
> > Glen Walpert wrote:
> >> On Tue, 30 Nov 2010 14:15:28 -0500, Rich Webb wrote:
> >>>> Thermocouples are really really horrible temperature sensors--almost
> >>>> as bad as ICs.  Their advantages are small size, relatively low cost,
> >>>> and (potentially) high speed, but their disadvantage is that it's
> >>>> really hard to get good measurements.
>
> >>>> One reason for this is thermal conduction down the leads (which is a
> >>>> big problem for most temperature sensors).  There's a worse one,
> >>>> though: due to their very low sensitivity, thermocouples are
> >>>> extremely vulnerable to errors caused by offset drift in the
> >>>> circuitry.  See Figure 20.3 on P. 803 at
> >>>>http://electrooptical.net/www/book/draftthermal.pdf
>
> >>> "Thermocouples generate a voltage related to the temperature
> >>> difference between two junctions of dissimilar metal wires, and are a
> >>> pain in the neck. ... For less specialized applications, avoid
> >>> thermocouples like fleas."
>
> >>> Okay, now I'm going to *have* to buy that book!
>
> >> Yes, that is a good one, and I can't argue with Phil's assessment of TC
> >> accuracy, but "You can learn all you ever wanted to know about them
> >> from the Omega Engineering catalogue." is true only if you have no
> >> interest in how they actually work (as opposed to how to use them) or
> >> how to make a really good low drift TC measurement system with accurate
> >> CJC and high immunity to EMI, for instance.
>
> >> There are many trade-offs in sensor selection, and thermocouples excel
> >> in temperature range and durability as well as (sometimes) speed.  A TC
> >> can be smashed flat with a hammer and suffer no loss in accuracy until
> >> the wires break, or welded to metal parts for excellent thermal contact
> >> with the part being measured, for instance.  Try that with a thermistor
> >> :-).
>
> > You can solder RTDs down, which is about the same thing.  And the
> > circuit details aren't really information about the _sensor_--any
> > sufficiently poor sensor will have those problems.
>
> > I've used thermocouples reasonably often, generally running inside an
> > evaporator or someplace like that, and attached to a Fluke thermocouple
> > thermometer with built-in cold junction compensation.  That was probably
> > good to a couple of degrees, which was all I really needed, especially
> > since I didn't have to replace the TCs, so the measurements correlated
> > pretty well over time.
>
> From the perspective of your book - temperature stabilization of electro-
> optical components - I agree completely that thermocouples should
> generally be avoided like fleas.  From my perspective, with a background
> in power plant control, thermocouples and RTD's are the rule and
> thermistors the rare exception.
>
> What really irks me about Omega is that their "Thermocouple Introduction
> and Theory" section is actually a "thermocouple introduction and
> completely bogus theory".  Correct theory can be found at:
> <http://www.electronics-cooling.com/Resources/EC_Articles/JAN97/
> jan97_01.htm>
>
> And better yet is another article which I can no longer find on the web,
> which I will post on ABSE with thread title "thermocouple theory article"
> in case anyone is interested.
>
> Glen- Hide quoted text -
>
> - Show quoted text -

Hmm, that link sends me to "Microthermal imaging in the infrared"
Nothing about thermal couples?

George H.

== 4 of 5 ==
Date: Fri, Dec 3 2010 10:24 am
From: hamilton

On 12/3/2010 10:59 AM, George Herold wrote:
> On Dec 3, 10:08 am, Glen Walpert<nos...@null.void> wrote:
>> On Wed, 01 Dec 2010 20:21:21 -0500, Phil Hobbs wrote:
>>> Glen Walpert wrote:
>>>> On Tue, 30 Nov 2010 14:15:28 -0500, Rich Webb wrote:
>>>>>> Thermocouples are really really horrible temperature sensors--almost
>>>>>> as bad as ICs. Their advantages are small size, relatively low cost,
>>>>>> and (potentially) high speed, but their disadvantage is that it's
>>>>>> really hard to get good measurements.
>>
>>>>>> One reason for this is thermal conduction down the leads (which is a
>>>>>> big problem for most temperature sensors). There's a worse one,
>>>>>> though: due to their very low sensitivity, thermocouples are
>>>>>> extremely vulnerable to errors caused by offset drift in the
>>>>>> circuitry. See Figure 20.3 on P. 803 at
>>>>>> http://electrooptical.net/www/book/draftthermal.pdf
>>
>>>>> "Thermocouples generate a voltage related to the temperature
>>>>> difference between two junctions of dissimilar metal wires, and are a
>>>>> pain in the neck. ... For less specialized applications, avoid
>>>>> thermocouples like fleas."
>>
>>>>> Okay, now I'm going to *have* to buy that book!
>>
>>>> Yes, that is a good one, and I can't argue with Phil's assessment of TC
>>>> accuracy, but "You can learn all you ever wanted to know about them
>>>> from the Omega Engineering catalogue." is true only if you have no
>>>> interest in how they actually work (as opposed to how to use them) or
>>>> how to make a really good low drift TC measurement system with accurate
>>>> CJC and high immunity to EMI, for instance.
>>
>>>> There are many trade-offs in sensor selection, and thermocouples excel
>>>> in temperature range and durability as well as (sometimes) speed. A TC
>>>> can be smashed flat with a hammer and suffer no loss in accuracy until
>>>> the wires break, or welded to metal parts for excellent thermal contact
>>>> with the part being measured, for instance. Try that with a thermistor
>>>> :-).
>>
>>> You can solder RTDs down, which is about the same thing. And the
>>> circuit details aren't really information about the _sensor_--any
>>> sufficiently poor sensor will have those problems.
>>
>>> I've used thermocouples reasonably often, generally running inside an
>>> evaporator or someplace like that, and attached to a Fluke thermocouple
>>> thermometer with built-in cold junction compensation. That was probably
>>> good to a couple of degrees, which was all I really needed, especially
>>> since I didn't have to replace the TCs, so the measurements correlated
>>> pretty well over time.
>>
>> From the perspective of your book - temperature stabilization of electro-
>> optical components - I agree completely that thermocouples should
>> generally be avoided like fleas. From my perspective, with a background
>> in power plant control, thermocouples and RTD's are the rule and
>> thermistors the rare exception.
>>
>> What really irks me about Omega is that their "Thermocouple Introduction
>> and Theory" section is actually a "thermocouple introduction and
>> completely bogus theory". Correct theory can be found at:
>> <http://www.electronics-cooling.com/Resources/EC_Articles/JAN97/
>> jan97_01.htm>
>>
>> And better yet is another article which I can no longer find on the web,
>> which I will post on ABSE with thread title "thermocouple theory article"
>> in case anyone is interested.
>>
>> Glen- Hide quoted text -
>>
>> - Show quoted text -
>
> Hmm, that link sends me to "Microthermal imaging in the infrared"
> Nothing about thermal couples?
>
> George H.
>
>
Did you fix the wrap ??

== 5 of 5 ==
Date: Fri, Dec 3 2010 12:10 pm
From: George Herold

On Dec 3, 1:24 pm, hamilton <hamil...@nothere.com> wrote:
> On 12/3/2010 10:59 AM, George Herold wrote:
>
>
>
> > On Dec 3, 10:08 am, Glen Walpert<nos...@null.void>  wrote:
> >> On Wed, 01 Dec 2010 20:21:21 -0500, Phil Hobbs wrote:
> >>> Glen Walpert wrote:
> >>>> On Tue, 30 Nov 2010 14:15:28 -0500, Rich Webb wrote:
> >>>>>> Thermocouples are really really horrible temperature sensors--almost
> >>>>>> as bad as ICs.  Their advantages are small size, relatively low cost,
> >>>>>> and (potentially) high speed, but their disadvantage is that it's
> >>>>>> really hard to get good measurements.
>
> >>>>>> One reason for this is thermal conduction down the leads (which is a
> >>>>>> big problem for most temperature sensors).  There's a worse one,
> >>>>>> though: due to their very low sensitivity, thermocouples are
> >>>>>> extremely vulnerable to errors caused by offset drift in the
> >>>>>> circuitry.  See Figure 20.3 on P. 803 at
> >>>>>>http://electrooptical.net/www/book/draftthermal.pdf
>
> >>>>> "Thermocouples generate a voltage related to the temperature
> >>>>> difference between two junctions of dissimilar metal wires, and are a
> >>>>> pain in the neck. ... For less specialized applications, avoid
> >>>>> thermocouples like fleas."
>
> >>>>> Okay, now I'm going to *have* to buy that book!
>
> >>>> Yes, that is a good one, and I can't argue with Phil's assessment of TC
> >>>> accuracy, but "You can learn all you ever wanted to know about them
> >>>> from the Omega Engineering catalogue." is true only if you have no
> >>>> interest in how they actually work (as opposed to how to use them) or
> >>>> how to make a really good low drift TC measurement system with accurate
> >>>> CJC and high immunity to EMI, for instance.
>
> >>>> There are many trade-offs in sensor selection, and thermocouples excel
> >>>> in temperature range and durability as well as (sometimes) speed.  A TC
> >>>> can be smashed flat with a hammer and suffer no loss in accuracy until
> >>>> the wires break, or welded to metal parts for excellent thermal contact
> >>>> with the part being measured, for instance.  Try that with a thermistor
> >>>> :-).
>
> >>> You can solder RTDs down, which is about the same thing.  And the
> >>> circuit details aren't really information about the _sensor_--any
> >>> sufficiently poor sensor will have those problems.
>
> >>> I've used thermocouples reasonably often, generally running inside an
> >>> evaporator or someplace like that, and attached to a Fluke thermocouple
> >>> thermometer with built-in cold junction compensation.  That was probably
> >>> good to a couple of degrees, which was all I really needed, especially
> >>> since I didn't have to replace the TCs, so the measurements correlated
> >>> pretty well over time.
>
> >>  From the perspective of your book - temperature stabilization of electro-
> >> optical components - I agree completely that thermocouples should
> >> generally be avoided like fleas.  From my perspective, with a background
> >> in power plant control, thermocouples and RTD's are the rule and
> >> thermistors the rare exception.
>
> >> What really irks me about Omega is that their "Thermocouple Introduction
> >> and Theory" section is actually a "thermocouple introduction and
> >> completely bogus theory".  Correct theory can be found at:
> >> <http://www.electronics-cooling.com/Resources/EC_Articles/JAN97/
> >> jan97_01.htm>
>
> >> And better yet is another article which I can no longer find on the web,
> >> which I will post on ABSE with thread title "thermocouple theory article"
> >> in case anyone is interested.
>
> >> Glen- Hide quoted text -
>
> >> - Show quoted text -
>
> > Hmm, that link sends me to "Microthermal imaging in the infrared"
> > Nothing about thermal couples?
>
> > George H.
>
> Did you fix the wrap ??- Hide quoted text -
>
> - Show quoted text -

That didn't help, but I searched the site for "thermocouple" and
found it near the end of the list.

George H.

==============================================================================
TOPIC: discount sale air jordan shoes (www.nike-black.com)
http://groups.google.com/group/sci.electronics.repair/t/981507dcb91c66c8?hl=en
==============================================================================

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==============================================================================
TOPIC: 100v--> 10V Trans. on 120V
http://groups.google.com/group/sci.electronics.repair/t/c8528fdeff78820d?hl=en
==============================================================================

== 1 of 5 ==
Date: Fri, Dec 3 2010 10:17 am
From: "Michael Kennedy"

I was wonderin if someone could educate me on Transformers.
Here I have a Japanese Nintendo which has a 100V to 10V wall wart iorn
transformer.
Am Im I correct in guessing that this transformer is going to output 12V on
120V power instead of 10V it would on 100V?

Not being in the USA at the moment I can't just check it and see what the
voltage is.

TIA

Mike

== 2 of 5 ==
Date: Fri, Dec 3 2010 10:57 am
From: nesesu

On Dec 3, 10:17 am, "Michael Kennedy" <m...@nospam.com> wrote:
> I was wonderin if someone could educate me on Transformers.
> Here I have a Japanese Nintendo which has a 100V to 10V wall wart iorn
> transformer.
> Am Im I correct in guessing that this transformer is going to output 12V on
> 120V power instead of 10V it would on 100V?
>
> Not being in the USA at the moment I can't just check it and see what the
> voltage is.
>
> TIA
>
> Mike

Yes, BUT.
Iron transformers are designed with only sufficient turns on the
primary to prevent the core beginning to saturate at the highest
expected voltate [~+10% or so] so if you try and run a transformer
designed for 100V nominal on 120V nominal the core will likely be
running into the saturation curve. This can give three effects: the
primary current draw will be excessive causing the wire to overheat,
the core running into saturation will overheat and finally, the output
waveform may be clipped causing a reduced output voltage compared to
what would be expected from the turns ratio. However, that transformer
may be specified for the Japanese 50Hz power in which case there will
be some extra margin so it could operate okay on 120V 60Hz [100V *
60/50Hz]
In other words, it is okay to run a transformer on lower primary
voltage than specified but not higher and it is okay to run a
transformer on a higher frequency than specified but not lower
[assuming typical power line frequencies 25-60Hz].

Neil S.

== 3 of 5 ==
Date: Fri, Dec 3 2010 1:08 pm
From: Meat Plow

On Sat, 04 Dec 2010 03:17:59 +0900, Michael Kennedy wrote:

> I was wonderin if someone could educate me on Transformers. Here I have
> a Japanese Nintendo which has a 100V to 10V wall wart iorn transformer.
> Am Im I correct in guessing that this transformer is going to output 12V
> on 120V power instead of 10V it would on 100V?
>
> Not being in the USA at the moment I can't just check it and see what
> the voltage is.
>
>
> TIA
>
> Mike

If the supply is rectified and well regulated it will output 10vdc or
there abouts.

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

== 4 of 5 ==
Date: Fri, Dec 3 2010 1:47 pm
From: "Phil Allison"

"nesesu"

Iron transformers are designed with only sufficient turns on the
primary to prevent the core beginning to saturate at the highest
expected voltate [~+10% or so]

** Only true for toroidal an C-core types - it is common practice to
allow the core of an E-core type to operate into some or even a lot of
saturation. The practice is almost universal with small PSUs containing
E-cores.

so if you try and run a transformer
designed for 100V nominal on 120V nominal the core will likely be
running into the saturation curve.

** See above.

This can give three effects: the
primary current draw will be excessive causing the wire to overheat,
the core running into saturation will overheat

** The operative word is "can" - chances are that the unit will tolerate
the increase.

and finally, the output
waveform may be clipped causing a reduced output voltage compared to
what would be expected from the turns ratio.

** Fraid you have gone right off the rails here.

Core saturation does NOT cause waveform clipping - for the simple reason
that the current draw increases only around the times of zero voltage on the
AC wave.

However, that transformer
may be specified for the Japanese 50Hz power in which case there will
be some extra margin so it could operate okay on 120V 60Hz [100V *
60/50Hz]

** Correct - almost all Japanese ( local market ) power transformers are
built for 100 volt AC @ 50 Hz operation.

About half the country has 50Hz power.

.... Phil

== 5 of 5 ==
Date: Fri, Dec 3 2010 4:20 pm
From: David Nebenzahl

On 12/3/2010 1:08 PM Meat Plow spake thus:

> On Sat, 04 Dec 2010 03:17:59 +0900, Michael Kennedy wrote:
>
>> I was wonderin if someone could educate me on Transformers. Here I have
>> a Japanese Nintendo which has a 100V to 10V wall wart iorn transformer.
>> Am Im I correct in guessing that this transformer is going to output 12V
>> on 120V power instead of 10V it would on 100V?
>>
>> Not being in the USA at the moment I can't just check it and see what
>
> If the supply is rectified and well regulated it will output 10vdc or
> there abouts.

How do you get DC out of a transformer? Must be a really special one ...

Of course, it's impossible to tell from the O.P. whether the thing in
question is really a transformer (outputs AC) or a power supply (outputs
DC).

To the OP, it would help us to know. What does it say on the wall wart?
Should say something like "10 VAC" or "10 VDC" or some such.

--
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: Sony KV27EXR20 Sound no picture
http://groups.google.com/group/sci.electronics.repair/t/41a66d907546cb08?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 3 2010 12:32 pm
From: b

On Nov 27, 3:23 am, mnpinball <mnpinb...@yahoo.com> wrote:UT, the
picture
> goes on then off and cycles like this every 2 seconds constantly.

This is the classic sign of a tired Sony tube. The AKB blanks out the
picture if one of the 3 guns is not emitting well.
There are a few 'bodges' such as changing the value of the heater feed
series resistor to 0R5 instead of 1R, and/or raising the SCREEN preset
on the line transformer, but these are short term fixes whose
effectivenss can generally be measured in weeks or months, if that.
I'd give it a try, but look around locally for another set. You can
get decent used sets from the likes of Hitachi and Toshiba for next to
nothing as people 'upgrade' to flat panels.
-B

==============================================================================
TOPIC: PS/2-to-AT keyboard adapter
http://groups.google.com/group/sci.electronics.repair/t/d8e9826e9e554abf?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 3 2010 4:33 pm
From: NoEmailAds@execpc.com (Chris Giese)

D Yuniskis <not.going.to.be@seen.com> wrote:

>don't expect any of the "magic buttons" common on
>newer keyboards to work.

Ah -- an added bonus :)

>Depends on what you call "old". E.g., I have still some Compaq
>Portable III's here (286 lunchbox).

The system in question is a Pentium 1 with 16 meg of RAM.

>Your local computer supply place will have them. Maybe even
>rat shak.

OK, I'll take a look.

Thanks everyone.

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