sci.electronics.repair@googlegroups.com

Today's topics:

* measuring ampermeter meter internal resistance - 11 messages, 6 authors
http://groups.google.com/group/sci.electronics.repair/t/27f050235cfa3de3?hl=en
* Ping Arfa (was Re: Another reason to hate CFLs ... - 9 messages, 9 authors
http://groups.google.com/group/sci.electronics.repair/t/87ea27a2579f0316?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

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

== 1 of 11 ==
Date: Sun, Oct 24 2010 11:19 am
From: Jamie

Jeff Liebermann wrote:

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

Actually, I can get sued for what I just said! Because its definition
of character for CA :)

== 2 of 11 ==
Date: Sun, Oct 24 2010 12:09 pm
From: Paul Keinanen

On Sun, 24 Oct 2010 14:01:56 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

>Paul Keinanen wrote:
>
>> On Sat, 23 Oct 2010 21:28:15 -0700 (PDT), mynick <anglomont@yahoo.com>
>> wrote:
>>
>>
>>>want to shunt a multimeter to extend it's ac ampermeter range so
>>>measured with Rish 14s
>>
>>
>> So good so far.
>>
>> According to the link the voltage drop is 270 mV at 10 A current.
>> This should not be hard to calculate the internal resistor of the
>> multimeter based of this information :-)
>>
>>
>>>in ohm meter position about 41 ohms
>>>and then measured with Rish 14s its own internal resistance to get 40
>>>ohms
>>>Is this way to much -there is some mistake?
>>
>>
>> Those values do not make any sense for any realistic current meter
>> (except for some extremely low current applications).
>>
>>
>>>(http://www.multimetercalibrationsaustralia.com.au/rishmulti14s.pdf
>>>but cannot find data about it's internal resistance!)
>>
>>
>> For your own safety, if the 10 Aac current range of the multimeter is
>> not enough, please consider using a current transformer for measuring
>> large 50/60 Hz currents.
>>
>> And remember that with current transformers, the secondary must
>> _always_ be shorted or connected to a low impedance meter.
>>
>Oh why did you have to tell him the last part! :)
>

You really learn a lot after serious mistakes,
however, what is the point of it, if you are killed by the first
mistake ?

== 3 of 11 ==
Date: Sun, Oct 24 2010 12:27 pm
From: David Sanders

On Sun, 24 Oct 2010 11:02:21 -0700, Jeff Liebermann wrote:

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

Who cares? My dick needs to be jacked.
--
Shit! I thought no one knew, goddammit!
http://preview.tinyurl.com/29p4ody
Me, jacking off! http://preview.tinyurl.com/3xpntge Available For
Lessons!

== 4 of 11 ==
Date: Sun, Oct 24 2010 1:09 pm
From: John Fields

On Sun, 24 Oct 2010 07:00:48 -0700, Fred Abse
<excretatauris@invalid.invalid> wrote:

>On Sat, 23 Oct 2010 21:31:15 -0700, someone calling himself "John Fields"
>wrote:
>
>> No Stupid, that's not the way to ampmeter range to higher range. Why did
>> you call yourself Superpower Punk? You don't even know how to multiple the
>> power of your electronic? You see, I am a superdumb-ass and I am very
>> capable to multiple current as well as AmpMeter by 10X.
>
>
>What a lousy impersonation.
>
>The John Fields that we all know (and love?) writes grammatically.
---
Thank you, sir! :-)

---
JF

== 5 of 11 ==
Date: Sun, Oct 24 2010 1:10 pm
From: John Fields

On Sun, 24 Oct 2010 08:53:52 -0700, "Proteus" <proteusiiv@gmail.com>
wrote:

>YOU ARE MORE FUCK-UP ASSHOLE FREAK!
>
>I AM PROTEUS

---
You are shit.

---
JF

== 6 of 11 ==
Date: Sun, Oct 24 2010 1:12 pm
From: John Fields

On Sun, 24 Oct 2010 08:56:53 -0700, "Proteus" <proteusiiv@gmail.com>
wrote:

>PETERDUMB,
>YOU SKUNKS KEPT FOLLOWING EACH OTHER TO SEWER. SOON THERE WON'T BE ANY
>SKUNK LEFT, DON'T YOU KNOW FREAK?
>
>YOU ARENT FOOLING ANYONE STUPID
>YOU AND JOHNNY THERE SHOULD GIVE IT A GO
>YOU ARE BOTH FREAKY FAGGOTY FOOLS
>
>I AM PROTEUS

---
You are shit.

---
JF

== 7 of 11 ==
Date: Sun, Oct 24 2010 2:40 pm
From: David Nebenzahl

On 10/24/2010 9:37 AM Fred Abse spake thus:

> On Sun, 24 Oct 2010 08:53:52 -0700, Proteus wrote:
>
>> "Fred Abse" <excretatauris@invalid.invalid> wrote in message
>> news:pan.2010.10.24.09.53.04.370083@invalid.invalid...
>>
>>> On Sat, 23 Oct 2010 21:31:15 -0700, someone calling himself "John
>>> Fields" wrote:
>>>
>>>> No Stupid, that's not the way to ampmeter range to higher
>>>> range. Why did you call yourself Superpower Punk? You don't
>>>> even know how to multiple the power of your electronic? You
>>>> see, I am a superdumb-ass and I am very capable to multiple
>>>> current as well as AmpMeter by 10X.
>>>
>>> What a lousy impersonation.
>>>
>>> The John Fields that we all know (and love?) writes
>>> grammatically.
>>
>> YOU ARE MORE FUCK-UP ASSHOLE FREAK!
>>
>> I AM PROTEUS
>
> http://maps.google.com/maps?ll=60.2631,-1.407736&spn=0.1,0.1&t=m&q=60.2631,-1.407736
>
> Plonk!

So I'm just a little curious. At the risk of opening a can of worms, I ask:

1. How did you get this geographic location from that posting?
2. Who, exactly, is "Proteus"?

Like I said, just curious, not dying to know ...

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

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

== 8 of 11 ==
Date: Sun, Oct 24 2010 3:05 pm
From: Robert Baer

mynick wrote:
> want to shunt a multimeter to extend it's ac ampermeter range so
> measured with Rish 14s in ohm meter position about 41 ohms
> and then measured with Rish 14s its own internal resistance to get 40
> ohms
> Is this way to much -there is some mistake?
> (http://www.multimetercalibrationsaustralia.com.au/rishmulti14s.pdf
> but cannot find data about it's internal resistance!)
Well, a good way to destroy a milliammeter movement is to use an
ohmmeter to measure its resistance (POOF!).
Take an adjustable low voltage supply in series with a resistor and
tweak for full scale reading.
Then connect an adjustable resistor across the meter and adjust for
half scale reading.
Remove that resistor and measure it.
I leave the proof to the student.

== 9 of 11 ==
Date: Sun, Oct 24 2010 3:13 pm
From: Robert Baer

mynick wrote:
> want to shunt a multimeter to extend it's ac ampermeter range so
> measured with Rish 14s in ohm meter position about 41 ohms
> and then measured with Rish 14s its own internal resistance to get 40
> ohms
> Is this way to much -there is some mistake?
> (http://www.multimetercalibrationsaustralia.com.au/rishmulti14s.pdf
> but cannot find data about it's internal resistance!)
Now that i told you how to determine (NOT directly measure) the
resistance of a meter, FORGET that happy horsemanure.
Use that low voltage adjustable supply and resistor in series;adjust
to get full scale reading.
Now...hold your breath...measure the VOLTAGE across the meter.
THAT is what you want your meter shunt to drop, for full scale reading.
So it does not matter if the meter was 5uA, 100uA or 1mA; treat it as
if it was a voltmeter, measuring the voltage drop across the ten amp
shunt (or whatever you wanted).
So, you asked the wrong question (internal resistance).

== 10 of 11 ==
Date: Sun, Oct 24 2010 3:14 pm
From: Robert Baer

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

== 11 of 11 ==
Date: Sun, Oct 24 2010 3:16 pm
From: Robert Baer

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

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

== 1 of 9 ==
Date: Sun, Oct 24 2010 11:23 am
From: Meat Plow

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?

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

== 2 of 9 ==
Date: Sun, Oct 24 2010 11:30 am
From: Jeff Liebermann

On Sun, 24 Oct 2010 13:37:01 -0400, Rich Webb
<bbew.ar@mapson.nozirev.ten> wrote:

>Cool stuff. Always interesting to "see" that what we perceive is not
>always (or often) 1:1 with what's really there.

Our eyes adapt very nicely to different color illumination. For
example, we see "white" light from a flourescent fixture, while the
light is heavily green tinged when viewed on an uncompensated
photograph taken with a digital or film camera.

>Make Magazine vol 24 (due out any day now) will have a DIY article on a
>hand-held diffraction grating spectroscope.
>http://makezine.com/magazine/ (Note that as of today the link shows
>volume 23; subscribers should have received an email link to number 24).

I've resisted subscribing because I know that I'll spend the rest of
my life building and playing with interesting toys. Sigh.

>There's also http://sciencefirst.com/product_info.php?products_id=403.
>It's kind of clunky (basically a kid's toy) but it does have an
>adjustable scale so it can be kinda-sorta calibrated using a known
>spectral line from a fluorescent lamp.

Some more on the Star Spectrometer.
<http://home.comcast.net/~mcculloch-brown/astro/spectwhat.html>
<http://home.comcast.net/~mcculloch-brown/astro/spectrostar.html>
<http://www.scientificsonline.com/precision-economy-spectrometer.html>

Kinda overkill for this application. All you need is a slit and a
glass prism.
<http://en.wikipedia.org/wiki/File:Simple_spectroscope.jpg>

If you want really simple, there are diffraction glasses and slides:
<http://www.mutr.co.uk/product_info.php?products_id=1009604>
<http://www.rainbowsymphonystore.com/difgratglas.html>
<http://www.scientificsonline.com/catalogsearch/result/?q=grating>

If you're really into crude, you can use a DVD as a diffraction
grating:
<http://www.mutr.co.uk/product_info.php?products_id=1009497>
<https://secure-mutr.co.uk/catalog/images/spectroscope.pdf?osCsid=8cckpjuiqluci60s4k6ubbhoc5>

Ummm....
<http://www.scientificsonline.com/party-bulbs.html>
Black bulb???

--
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

== 3 of 9 ==
Date: Sun, Oct 24 2010 11:30 am
From: Jeffrey Angus

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

== 4 of 9 ==
Date: Sun, Oct 24 2010 12:36 pm
From: "William Sommerwerck"

>>>> 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.

What is it about UseNet that attracts "human beings" who have nothing better
to do than behave in a nasty, insulting fashion to anyone who displeases
their sense of arrogant self-importance? What do your friends see in you
two, anyway?

I've had private communications with Mr Plow, who made it clear he has the
absolute right to say whatever he likes, for whatever reason, and no one has
any right to question or criticize him. He doesn't want friends; he just
wants to be surrounded by people who will graciously allow him to abuse
them.

You wouldn't dare spew your nastiness directly in the face of any member of
this group. You're sniveling cowards hiding behind the physical anonymity of
a UseNet group.

What rotten "people" you are.

PS: Posting anything in a group implicitly opens the subject for discussion.

== 5 of 9 ==
Date: Sun, Oct 24 2010 12:49 pm
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

So bipolar, not triacs, from the philips pdf. Also 105 deg C not F for the
caps, previously stated

== 6 of 9 ==
Date: Sun, Oct 24 2010 2:05 pm
From: Rich Webb

On Sun, 24 Oct 2010 11:30:14 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Sun, 24 Oct 2010 13:37:01 -0400, Rich Webb
><bbew.ar@mapson.nozirev.ten> wrote:
>
>>Cool stuff. Always interesting to "see" that what we perceive is not
>>always (or often) 1:1 with what's really there.
>
>Our eyes adapt very nicely to different color illumination. For
>example, we see "white" light from a flourescent fixture, while the
>light is heavily green tinged when viewed on an uncompensated
>photograph taken with a digital or film camera.

Yup, a lot of what we see is really what we perceive, and we're rather
easy to fool.

Some illuminating illustrations of this are over at:
http://www.lottolab.org/articles/illusionsoflight.asp

--
Rich Webb Norfolk, VA

== 7 of 9 ==
Date: Sun, Oct 24 2010 2:34 pm
From: David Nebenzahl

On 10/24/2010 8:32 AM Arfa Daily spake thus:

> "David Nebenzahl" <nobody@but.us.chickens> wrote in message
> news:4cc390a0$0$2453$822641b3@news.adtechcomputers.com...
>
>> On 10/23/2010 6:28 PM Arfa Daily spake thus:
>>
>>> 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.
>>
>> Hate to say it, Arfa, but you sound like a Croat ranting about how
>> much he hates automobiles, having driven nothing but Yugos all his
>> life.
>>
>> CFLs used to be like that, sure. The ones I use (here in the Untied
>> Snakes) are much better in all the parameters you mentioned:
>> instant on, no appreciable warm-up time, pleasing color spectrum,
>> long life.
>>
>> (Well, their packages still leave something to be desired in some
>> applications, but other than that they're good.)
>
> Over the years since this technology was vaunted as the 'replacement'
> for incandescent light, I have bought many examples from different
> manufacturers. Whilst there has been some improvement in their
> performance in that time, they remain, IMHO, a 'substitute'
> technology, rather than a 'replacement' one. They do not start up in
> the few mS that it takes an incandescent to come on, no matter how
> good and up to date they are in that respect. Neither do they reach
> full output for some considerable time after they are powered. Most
> seem to be rated to produce 80% of their maximum light output after
> 15 seconds. The remaining 20% takes a lot longer than that. Both
> shortcomings are exacerbated by low ambient temperature. The power
> ratings and light output are typically specced for an ambient
> temperature of 25 deg C. Whilst some parts of the world may achieve
> this most of the time, we don't here in the UK, and UK homes are
> certainly not heated to that level from autumn through spring. Apart
> from that, they don't sit properly in many decorative light fittings,
> and change the colour aesthetics of some lampshades - notably for
> instance, in a rather nice Tiffany style table lamp that I have. When
> I tried one in that, the beautiful ruby red panels changed to a muddy
> colour, and the whole shade took on a muted look, with much of the
> colour vibrancy that is a trademark of this type of shade, gone. I
> went back to an incandescent in it. I was able to use a clear one, as
> the bulb is not visible.

[snip]

First let me say that I totally believe you and your tale of woe
concerning CFLs vs. incandescents.

But as someone else here pointed out, this merely points to what is
apparently the comparatively poor availability of decent CFLs in your
island nation compared to other places (U.S., for example). More's the pity.

And yes, contrary to your strenuous assertions to the contrary, there
*are* compelling environmental and energy-conservation reasons to switch
to CFLs, and damn fast too. Not just some empty-headed notion from tree
huggers.

But it would be in the best interests of UK citizens if they were
presented a decent range of alternatives to incandescent bulbs before
being forced to give them up. The process actually seems to be going
pretty well on this side of the ocean, with many people switching on
account of a good range of inexpensive alternatives to the old
heat-producers.

--
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)

== 8 of 9 ==
Date: Sun, Oct 24 2010 3:54 pm
From: LSMFT

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

People like you have real issues. I have had 100% CFL's in my home for
decades. Guess what, they are better than candles.
I will be switching to LED's when they are available for all around use.

--
LSMFT

Simple job, assist the assistant of the physicist.

== 9 of 9 ==
Date: Sun, Oct 24 2010 4:29 pm
From: "Wild_Bill"

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

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

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

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

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

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

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

==============================================================================
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: Sun, Oct 24 2010 12:11 pm
From: PlainBill47@yawho.com

On Sat, 23 Oct 2010 13:05:23 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

>> Any electronics technician should be able to solve this
>> by inspection; no calculator necessary. 3K/1k = x/40,
>> therefore x= 120 ohms. Come up with more difficult ones
>> next time.
>
>What do you mean by "inspection"? Are you applying a formula you memorized?
>Or do you /understand/ what's involved?
>Probably better than you do. The voltage across R1 is 1/4 of +VDC. An op-amp tries to force both inputs to the same voltage. Since it was stipulated the op-amp is a 'classic, ideal' op amp, we can assume it has none of the defects found in the real world. As a result the voltage across R3 will also be 1/4 of VDC. The only way that can happen is if the effective resistance of Q1 is 3 times the resistance of R3, or 120 ohms.

NOW, what is less certain is the proper answer to the problem
"Calculate the equivalent resistance of this programmable load."
Given that R1, R2, and R3 are all part of the load, the proper answer
to the original diagram is 153.846 ohms. Except that circuit does not
show any evidence of being 'programmable'.

PlainBill

== 2 of 5 ==
Date: Sun, Oct 24 2010 2:50 pm
From: Robert Baer

ehsjr wrote:
> RosemontCrest wrote:
>> On Oct 22, 8:04 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
>> wrote:
>>
>>> RosemontCrest wrote:
>>>
>>>
>>>> I routinely use the following question to test candidates for EE or TE
>>>> positions. For many years, it continues to stump all but one of many.
>>>> Is it really that difficult to solve?
>>>
>>>> http://smg.photobucket.com/albums/v18/RosemontCrest/?action=view&curr...
>>>>
>>>
>>>> or
>>>
>>>> http://preview.tinyurl.com/2c8udf9
>>>
>>>> I see two ways to solve it. The preferred method is to use Ohm's law
>>>> and nodal analysis without regard to the value of +VDC. Another method
>>>> is to assign a value to +VDC and solve it that way; I find that method
>>>> lame. Is this question, or test, too challenging for a BSEE graduate?
>>>
>>>> For entertainment only, I invite any of you to provide the solution
>>>> using only nodal analysis without consideration of the value of +VDC
>>>> (showing or explaining your work). There are bonus points that have no
>>>> value for calculating the exact equivalent resistance.
>>>
>>> Then make your challenge on the proper newsgroup:
>>> news:sci.electronics.design which is where you'll find the EEs.
>>>
>>> --
>>> Politicians should only get paid if the budget is balanced, and there is
>>> enough left over to pay them.
>>
>>
>> Thank you Michael. I was not sure to which sci.electronics.* group I
>> should post. Thanks for adding sci.electronics.design to this thread.
>
> Maybe it's too easy. It is instantly obvious that Rfet has to be
> 3 times R3. So, an applicant may think it's a trick question, and
> be wracking his brains looking for the trick. OTOH, it could
> eliminate those who are not confident enough in their understanding
> of it to say "160 ohms in parallel with 4000 ohms" or "about 153.8
> ohms".
>
> Ed
OOOhhhhh; you want a trick question based on real life?
Ages ago i went to an interview for a job.
They insisted that they had d'Arsonval meters that slowly decreased
their sensitivity...toward zero (!!).
The claim was that the Alnico magnets slowly lost their magnetism.
I told them that was completely impossible; maybe a magnetic loss of
one percent in a century, but not 90% in weeks.
Did not get the job, because they "knew" they were right.
I later found out those meters were in series with the plate of the
RF final for their plywood dryer product line.
Bypass on the low side of the meter was an electrolytic capacitor.
Like in Groucho Mark's Bet your Life, when i heard that, the duck
came down!

== 3 of 5 ==
Date: Sun, Oct 24 2010 2:51 pm
From: Robert Baer

Tim Williams wrote:
> "ehsjr" <ehsjr@nospamverizon.net> wrote in message
> news:ia0bhf$3os$1@news.eternal-september.org...
>> Maybe it's too easy. It is instantly obvious that Rfet has to be
>> 3 times R3. So, an applicant may think it's a trick question, and
>> be wracking his brains looking for the trick. OTOH, it could
>> eliminate those who are not confident enough in their understanding
>> of it to say "160 ohms in parallel with 4000 ohms" or "about 153.8
>> ohms".
>
> Don't be so optimistic. Kids have a lot of trouble with controlled
> sources.
>
> Tim
>
..like a few Curies of radium?

== 4 of 5 ==
Date: Sun, Oct 24 2010 3:19 pm
From: brent

On Oct 22, 11:04 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
wrote:
> RosemontCrest wrote:
>
> > I routinely use the following question to test candidates for EE or TE
> > positions. For many years, it continues to stump all but one of many.
> > Is it really that difficult to solve?
>
> >http://smg.photobucket.com/albums/v18/RosemontCrest/?action=view&curr...
>
> > or
>
> >http://preview.tinyurl.com/2c8udf9
>
> > I see two ways to solve it. The preferred method is to use Ohm's law
> > and nodal analysis without regard to the value of +VDC. Another method
> > is to assign a value to +VDC and solve it that way; I find that method
> > lame. Is this question, or test, too challenging for a BSEE graduate?
>
> > For entertainment only, I invite any of you to provide the solution
> > using only nodal analysis without consideration of the value of +VDC
> > (showing or explaining your work). There are bonus points that have no
> > value for calculating the exact equivalent resistance.
>
>    Then make your challenge on the proper newsgroup:
> news:sci.electronics.design which is where you'll find the EEs.
>
> --
> Politicians should only get paid if the budget is balanced, and there is
> enough left over to pay them.

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.

== 5 of 5 ==
Date: Sun, Oct 24 2010 3:55 pm
From: TheGlimmerMan

On Sat, 23 Oct 2010 13:28:58 -0700 (PDT), linnix <me@linnix.info-for.us>
wrote:

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

Not if you have a title.

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