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

sci.electronics.repair
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Today's topics:

==============================================================================
TOPIC: Testing SMPS
http://groups.google.com/group/sci.electronics.repair/t/1cc72f0926af56cc?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, Oct 23 2010 3:18 pm
From: Fred McKenzie

In article <i9u60e$m0o$1@news.eternal-september.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

> Now I own a 0.1 deg Fahrenheit resolution non-contact IR thermometer , the
> next problem SMPS I come across will get a scan across before ESRing
> 18GBP and its already found the awkward problem area of an analogue amp,
> well worth adding to any repairman's toolkit
> badged in UK as Maplin N19FR
> http://www.maplin.co.uk/module.aspx?moduleno=220790
> it has a scan mode , not mentioned in instructions

I have a Sears Craftsman model 50466. It resembles the "Infrared
Thermometer" shown below the pocket version in your reference, and has a
laser for aiming. "Scan" mode apparently means that it reads
continuously as long as you hold the button. When you let go of the
button, it holds the last reading for 7 seconds.

I've noticed that a GFCI outlet may be about 8 degrees F higher than
room temperature. The doorbell transformer is 7 degrees higher. It has
proven quite handy when looking for hot components. However, you need
to be aware that the sensor reads a spot that has finite size. You
could be reading an adjacent resistor instead of a capacitor!

Fred

== 2 of 2 ==
Date: Sat, Oct 23 2010 9:54 pm
From: "Michael A. Terrell"

N_Cook wrote:
>
> I imagine with .1 deg F resolution , if you could get inside and get some
> sort of decoded feed (LCD to BCD or whatever) out to a pc plus mount on an
> X/Z platform driven by geared down pair of stepper motors and a bit of
> colouring software you could make a poor-mans IR survey camera system.
> Perhaps a scan taking a few minutes rather than near real time.

You want a thermal imager, not a thermometer.

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

==============================================================================
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 10 ==
Date: Sat, Oct 23 2010 3:35 pm
From: Rich Grise

On Fri, 22 Oct 2010 22:34:47 -0700, linnix wrote:

> On Oct 22, 9:53 pm, Rich Grise <richgr...@example.net> wrote:
>>
>> ((Vdc/4)/40) A.
>
> It's not asking for I, but Req.
>
Oh, OK: Vcd/(((Vdc/4)/40) A).

Hope This Helps!
Rich

== 2 of 10 ==
Date: Sat, Oct 23 2010 3:47 pm
From: "William Sommerwerck"

>>> So if this is so all-fired obvious, why are we getting
>>> different answers?
>>> A. 153.8 ohms
>>> B. 120 ohms
>>> Both can't be correct, obviously. Which one is?

>> I don't mean to be offensive, but if you /understood/ the principle of
>> anaysis -- which is actually quite trivial -- there would be no question.

> Well, duh. Obviously, I don't. Perhaps someday I may.

>> The resistance of the JFET itself is 120 ohms, which is what
>> we're looking for, regardless of how the question is phrased.

> So I ask, perhaps naively: is this basically the same as finding
> the Thévenin equivalent of the circuit?

No. In fact, one of the things the testee has to recognize is that this
question has /nothing/ to do with the Norton or Thévenin equivalents, and
you're only going to confuse the hell out of yourself if you go in that
direction.

The principle is this... In a stable op-amp circuit, the feedback forces the
inverting and non-inverting inputs /to have the same voltage/. The rest is
trivial arithmetic.

== 3 of 10 ==
Date: Sat, Oct 23 2010 3:58 pm
From: Hammy

hamilton <hamilton@nothere.com> wrote in
news:i9vgc0$l99$1@news.eternal-september.org:

> Silly tests like this shows how a manager will behave after being
> hired.
>
> These tests work both ways.
>
> h

At least its technical.When I first graduated I had an interview with a
large comunications corp and not one question had anything to do with
electronics. I think the HR department gets their interview questions
from COSMO. I felt like I was answering one of those dumb womans
magazines quizes.

My experience was the smaller comapainies tended to be more intrested
in your technical understanding the larger ones seemed more intrested
in your psych profile.

I choked on one 6 guys asking me to reproduce the LNA I did in school I
think I screwed up all my symbols and couldnt explain the bias network
;brainfart.

Oh well it all worked out OK I make more money now then any of those
jobs so no compalints.

== 4 of 10 ==
Date: Sat, Oct 23 2010 4:02 pm
From: David Nebenzahl

On 10/23/2010 3:47 PM William Sommerwerck spake thus:

[me wrote:]

>> So I ask, perhaps naively: is this basically the same as finding
>> the Thévenin equivalent of the circuit?
>
> No. In fact, one of the things the testee has to recognize is that this
> question has /nothing/ to do with the Norton or Thévenin equivalents, and
> you're only going to confuse the hell out of yourself if you go in that
> direction.
>
> The principle is this... In a stable op-amp circuit, the feedback forces the
> inverting and non-inverting inputs /to have the same voltage/. The rest is
> trivial arithmetic.

Aha. Nice trick question, that.

So I learned something today. Thanks for your patience.

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

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

== 5 of 10 ==
Date: Sat, Oct 23 2010 4:22 pm
From: "William Sommerwerck"

>>> So I ask, perhaps naively: is this basically the same as finding
>>> the Thévenin equivalent of the circuit?

>> No. In fact, one of the things the testee has to recognize is that this
>> question has /nothing/ to do with the Norton or Thévenin equivalents, and
>> you're only going to confuse the hell out of yourself if you go in that
>> direction.

>> The principle is this... In a stable op-amp circuit, the feedback
>> forces the inverting and non-inverting inputs /to have the same
>> voltage/. The rest is trivial arithmetic.

> Aha. Nice trick question, that.
> So I learned something today. Thanks for your patience.

Thank /you/ for thinking, and asking good questions.

== 6 of 10 ==
Date: Sat, Oct 23 2010 4:49 pm
From: RadioJ

Maybe, those students have a lot of material thrown at them in a short
time. I've met both techs and engineers out of school who either "get"
op-amp theory or not... it's really just common sense on the basics. For
me, it was one practical app (and it was in a job interview that I
flunked) to cause me to get my a$$ in gear and figure it out for good.

Haven't done this stuff in while (used to do elect design but no BSEE..
just an "almost" AS in EET), and was sick/bored today, so here's some
bloated math... are you giving your potential candidates a couple of
hours to give the answer in terms of the resistors? :-)

For the over-all load on VDC:

Req = (R1 + R2) / (1 + (R1 / R3))

For just the output network:

Req = ((R1 + R2) * R3) / R1

---------------------------------
Proof-

Since non-inverting input and VR3 will be at the same voltage:

VR3 = (R1 * VDC) / (R1 + R2)

Solving for VDC:

VDC = (VR3 * (R1 + R2)) / R1

.....

IR3 = VR3 / R3

Resistance just for the output side, since current through JFET and R3
are same:

Rout = VDC / IR3

Substituting from above:

Rout = ((VR3 * (R1 + R2)) / R1) / (VR3 / R3)

Rout = ((R1 + R2) * R3) / R1

Check:

Rout = ((1k + 3k) * 40) / 1k = 160 ohms

Considering the input network, Rin:

Rin = R1 + R2

For overall load, using conductance, easier to calculate parallel:

Geq = (1 / Rout) + (1 / Rin)

Geq = (R1 / ((R1 + R2) * R3)) + (1 / (R1 + R2))

Geq = 1 / ((1 / (R1 + R2)) * (1 + (R1 / R3)))

Req = 1 / Geq

Req = (R1 + R2) / (1 + (R1 / R3))

Check:

Req = (1k + 3k) / (1 + (1k / 40))

Req = 153.85

----------------------

On 10/22/2010 10:59 PM, 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&current=programmableload.jpg
>
> 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.
>
> Thanks,
> Brian

== 7 of 10 ==
Date: Sat, Oct 23 2010 8:31 pm
From: Robert Baer

John Fields wrote:
> On Fri, 22 Oct 2010 19:59:39 -0700 (PDT), RosemontCrest
> <rosemontcrest@yahoo.com> 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&current=programmableload.jpg
>>
>> 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.
>
>
> Since R2R1 is a voltage divider, the voltage on U1+ will be:
>
> +VDC * R1
> U1+ = -----------
> R1 + R3
>
> Now, since the voltage on U1- must be equal to the voltage on U1+, and
> since R(Q1)R3 is another voltage divider,
>
> (+VDC * R3) - ((U1+) * R3)
> R(Q1) = ----------------------------
> U1+
>
> For the value, since the ratio of R2:R1 = 3 and the voltage across R1
> and R3 are equal, the ratio of R(Q1) to R3 must also be 3, making the
> FET's resistance 3 * R3 = 120 ohms.
>
> ---
> JF
Aww...i wanted to solve it without your hints.
But a quick look at the schematic makes it obvious that Req (of the
fet) is 120 ohms; took me a long 5 seconds (should have been less than
one second, so my 70+ years seems to be slowing me down).
Work? What work? ...

== 8 of 10 ==
Date: Sat, Oct 23 2010 8:56 pm
From: isw

In article <i9vome$jd1$1@news.eternal-september.org>,
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

> >>> So if this is so all-fired obvious, why are we getting
> >>> different answers?
> >>> A. 153.8 ohms
> >>> B. 120 ohms
> >>> Both can't be correct, obviously. Which one is?
>
> >> I don't mean to be offensive, but if you /understood/ the principle of
> >> anaysis -- which is actually quite trivial -- there would be no question.
>
> > Well, duh. Obviously, I don't. Perhaps someday I may.
>
>
> >> The resistance of the JFET itself is 120 ohms, which is what
> >> we're looking for, regardless of how the question is phrased.
>
> > So I ask, perhaps naively: is this basically the same as finding
> > the Thévenin equivalent of the circuit?
>
> No. In fact, one of the things the testee has to recognize is that this
> question has /nothing/ to do with the Norton or Thévenin equivalents, and
> you're only going to confuse the hell out of yourself if you go in that
> direction.
>
> The principle is this... In a stable op-amp circuit, the feedback forces the
> inverting and non-inverting inputs /to have the same voltage/. The rest is
> trivial arithmetic.

That statement is so significant, and so rarely understood...

Isaac

== 9 of 10 ==
Date: Sat, Oct 23 2010 9:09 pm
From: ehsjr

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".

== 10 of 10 ==
Date: Sat, Oct 23 2010 10:08 pm
From: "Tim Williams"

"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

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

==============================================================================
TOPIC: InovaBrasil
http://groups.google.com/group/sci.electronics.repair/t/624ffa93ca640b05?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, Oct 23 2010 4:55 pm
From: Rogerio

As mais lidas da semana em http://inovabrasil.blogspot.com

1. SECT - ES: 7ª Semana de Ciência e Tecnologia - Ciência para o
desenvolvimento sustentável
2. Protec: 6º Prêmio Inovar para Crescer
3. José Goldemberg ganha prêmio Ernesto Illy
4. CNPq: R$ 30 milhões para INCT em ciências do mar
5. Evolução ao Nível de Espécie: Répteis da América do Sul
6. Campinas lidera inovação entre 90 cidades avaliadas
7. Concurso público para CNPq e Biblioteca Nacional
8. CTIC: três novas chamadas
9. Faperj: criada bolsa de doutorado-sanduíche e assinados acordos
com instituições estrangeiras
10. UFRJ: Pesquisa sobre enzimas pode ajudar no controle de
infecções por fungos e protozoários (Candida albicans e parapsllosis)
11. INPE - CEM: treinamento em geoprocessamento com software livre
TerraView
12. 4ª Conferência Regional sobre Mudanças Globais
13. Finep: R$ 120 milhões para inovação no setor de esportes (14-
BIS)
14. Fundação Maria Cecília Souto Vidigal e FAPESP: apoio a pesquisas
em desenvolvimento infantil
15. Capes: sai o resultado do PNPD - Programa Nacional de Pós-
Doutorado
16. Fapeg: bolsas de estudo para docentes da UEG
17. FAPERJ: sai resultado do programa Equipamento Solidário
18. Fundect: edital para apoiar programas de pós-graduação
19. Mudanças Climáticas Globais – Desafios e oportunidades de
pesquisa
20. Santander Universidades: R$ 700 mil à Funcamp
21. Telegrafada a primeira fotografia em 1906
22. BIOEN Workshop on Molecular Mechanisms of Photosynthesis
23. CNPq: edital de apoio a identificação molecular da
biodiversidade (PPbIO - BR-BoL)
24. Embrapa e Unochapecó: aberta seleção de candidatos para
incubadora tecnológica
25. Lançado edital relacionado à avaliação de tecnologias em saúde -
REBRATS
26. Miguel Nicolelis receberá o NIH Director's Transformative R01
Award em 2010
27. OEPAS: Pesquisa agropecuária estadual tem apoio do governo
federal
28. Anpocs: TEM Circuito de Ciência e Tecnologia em Caxambu
29. Assinado protocolo de Nagoya-Kuala Lumpur sobre responsabilidade
e compensação de danos causados por transgênicos
30. BID: Bahia apresenta melhor programa de APLs do paí
31. Sebrae: R$122 milhões para inovação

Assine, apóie e divulgue o InovaBrasil.

Assinaturas : inovabrasil.assina@gmail.com
Twitter: @Inovabrasil2010

==============================================================================
TOPIC: Vox AD30VT small combo, 2007, PbF
http://groups.google.com/group/sci.electronics.repair/t/d5851d8e1a65198c?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, Oct 23 2010 5:48 pm
From: Arfa Daily

On 23/10/2010 16:37, Meat Plow wrote:
> On Sat, 23 Oct 2010 02:11:15 +0100, Arfa Daily wrote:
>
>> "N_Cook"<diverse@tcp.co.uk> wrote in message
>> news:i9s9fu$jr$1@news.eternal-september.org...
>>> In the end it was duff PbF solder meeting 50 yearold technology, the
>>> pcb-type pins of the valveholder. After redoing solder could simulate
>>> the reported previous intermittant situation of half power and no
>>> power by hovering a variously angled hot valve over the socket pins.
>>> The 2 cathodes are tied to -15V , beyond that quite complex, traces to
>>> njm2082 dual FET opamp and the DG211 an. sw. etc, certainly no proper
>>> anode Vs
>>>
>>>
>>>
>> Do you have a schematic for it ? This Vox is pretty similar
>>
>> http://www.blueguitar.org/new/schem/misc_amp/vox_vr30reverb.pdf
>>
>> and also uses a 12AX7 with an anode supply of just 15v, and it does
>> appear to be configured as a conventional genuine amplifier stage. I
>> seem to recall Elektor magazine doing some stuff with ECC / 12AX series
>> twin triodes. operating with low anode voltages.
>>
>> Arfa
>
> Don't they call that a starved cathode configuration?
>
>
>
Starved anode, I think.

Arfa

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

== 1 of 5 ==
Date: Sat, Oct 23 2010 6:28 pm
From: "Arfa Daily"

As if any more reasons were needed on top of their horrible startup
characteristics, their ugliness, their sick coloured light, and their
inability to last for a fraction of the claimed lifetime :-(

Like most of us, I suspect, I have hundreds of component drawers, which over
the years have become mixed up and confused, so in the circumstances of work
being very quiet at the moment, I decided to have a major tidy up and clear
out of redundant components. As a first move, I decided to rationalise the
resistors, and re-store them by individual value, rather than in groups of
values in the same drawer.

Now the other day, the bulb in my Anglepoise bench light failed, and as it
was the last 60 watt pearl one I had - nowhere stocking such an animal any
more due to EU ecobollox intervention - I put in a CFL that had come free
in a cornflake packet or some such nonsense. Once it has warmed up in the
morning - at least one coffee drinking time needed for this - it seemed to
work reasonably well. Until, that is, I started trying to identify the
resistors in my old drawers to move them into the individual value drawers
in the new location.

The spectrum from this lamp is so poor and discontinuous, that it is almost
impossible to resolve red from brown from orange, or violet from blue or
grey. Absolutely bloody useless. If I can't find any more 60 watt pearl
bulbs on the 'net, then I'm going to modify the lampholder to take a low
voltage halogen downlighter bulb, and hook it to a 12v transformer.

Arfa

== 2 of 5 ==
Date: Sat, Oct 23 2010 6:35 pm
From: "Phil Allison"

"Arfa Daily is a Bloody Whinger "

> 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.

** FFS - get a CFL that is rated for "Daylight White" colour balance.

My bench ( planetary arm) lamp uses a 22 watt " Daylight 6400K " spiral
CFL.

The light quality and quantity are both excellent.

.... Phil

== 3 of 5 ==
Date: Sat, Oct 23 2010 6:50 pm
From: David Nebenzahl

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.)

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

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

== 4 of 5 ==
Date: Sat, Oct 23 2010 10:07 pm
From: D Yuniskis

Hi David,

David Nebenzahl wrote:
> 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.

Sadly, our experience (also US) has not been that satisfying.
Warmups of 15-30 seconds and I don't think any have lasted
more than 2 years. We have been replacing them with commercial
grade incandescents as they blow out (and donating the "free
replacement" bulbs to a local charity).

We've tried three different brands and have been disgusted
with all of them. (neighbors seem to share our opinion)

And the "dimmable" lamps are absolutely worthless.

> (Well, their packages still leave something to be desired in some
> applications, but other than that they're good.)

== 5 of 5 ==
Date: Sat, Oct 23 2010 10:08 pm
From: Jeff Liebermann

On Sun, 24 Oct 2010 02:28:14 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

>Now the other day, the bulb in my Anglepoise bench light failed, and as it
>was the last 60 watt pearl one I had - nowhere stocking such an animal any
>more due to EU ecobollox intervention

One of these?
<http://www.shopadilly.co.uk/Auctions/vintage+anglepoise+lamp>

Ummm.... there should be a sticker on the Angelpoise desk lamp
indicating that due to the miserable ventilation design, the maximum
incandescent light bulb size is 60 watts. Anything bigger will blow
up rather rapidly due to overheating, as I found out in my previous
lamp. My current lamp is a Ledu, which specifies 75 watts max, mostly
because it has much larger vent holes and side ventilation slots.

>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.

You're using junk CFL bulbs. The ones I buy come on instantly. I do
have one in the kitchen that I'm too lazy to replace that takes a few
minutes to warm up. The others are almost instant on. CFL bulbs are
available in various color temperatures.

If you have a glass prism or diffraction grating, you can test your
bulbs for color spectra. Incandescent shows a continuous spectra,
while CFL shows a series of discontinuous color blobs. If the color
of your resistor band is missing from the spectra, you will have
problems even if all the other colors are present. See spectrum photo
on the right of:
<http://en.wikipedia.org/wiki/Compact_fluorescent_lamp#Spectrum_of_light>
Also, look for CRI on the package. The closer to 100, the better:
<http://en.wikipedia.org/wiki/Color_rendering_index>

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

==============================================================================
TOPIC: varicap diode testing?
http://groups.google.com/group/sci.electronics.repair/t/91a7f7edae59afb9?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, Oct 23 2010 9:09 pm
From: mynick

On Oct 20, 10:32 pm, Jeff Liebermann <je...@cruzio.com> wrote:
> On Wed, 20 Oct 2010 19:18:25 -0700 (PDT), mynick <anglom...@yahoo.com>
> wrote:
>
>
>
> >On Oct 18, 9:37 am, Jeff Liebermann <je...@cruzio.com> wrote:
> >> On Mon, 18 Oct 2010 06:41:25 -0700 (PDT), mynick <anglom...@yahoo.com>
> >> wrote:
>
> >> >if you test an OK varicapdiode with analog reistance meter what are
> >> >you supposed to get?
>
> >> Avaricapis just an ordinary diode. When reverse biased, it acts as
> >> a capacitor which varies with the applied reverse bias. It never
> >> conducts current in the forward direction. Never... Ever...
>
> >> >Does it get hot/warm in battery powered
> >> >transmitter
>
> >> No.
>
> >> >(if not than the element suspected to be a varactor and
> >> >mounted to stick a little bit out of the transmitter box, could be
> >> >an ic diode although it could not transmit trough walls, could it?)
>
> >> I have no idea. Perhaps it would be helpful if you would disclose:
> >> 1. What are you trying to accomplish?
> >> 2. What are you working on? (Make and model)?
> >> 3. What have you done so far and what happen?
> >this is a photo of the outdoor part of the wireless thermometer that
> >stopped working
> >http://img517.imageshack.us/img517/7053/img00331n.jpg
>
> Blurrrrrrry useless photo. Try again, this time with the camera set
> to macro, and without the drastic tilt angle, which requires too much
> depth of field.
>
> >checked discrete elements ok but no bias voltage at (varicap?)diode-
> >that, kind of
> >a transparent element, seen up front close to battery contacts having
> >resistance in both directions od 6Kohms,
> >any ideas?
>
> Nope. See my 3 questions.
>
> I've had far too much entertainment with wireless weather stations.
> They don't seem to fail, but they do drift off frequency, or lose
> power output due to moisture absorption in the PCB. I cheat and use a
> spectrum analyzer to look at what it's sending. To the best of my
> knowledge, most such remote thermometers do not use avaricap.
> However, the humidity sensor is a polyimide or polystyrene capacitor,
> with no case. The capacitor changes value as the dielectric absorbs
> moisture and swells.
>
> --
> Jeff Liebermann je...@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558

thanks
the 'varicap' mentioned then might be a temp sensor(no humidity)
as for frequency (589M says on the box)drift adjusting the screw near
top of pic1 did not help
I wonder where is the antenna input
please se
http://img233.imageshack.us/img233/9038/img00333.jpg
http://img6.imageshack.us/img6/9894/img00336q.jpg

== 2 of 2 ==
Date: Sat, Oct 23 2010 9:46 pm
From: Jeff Liebermann

On Sat, 23 Oct 2010 21:09:41 -0700 (PDT), mynick <anglomont@yahoo.com>
wrote:

>On Oct 20, 10:32 pm, Jeff Liebermann <je...@cruzio.com> wrote:
>> On Wed, 20 Oct 2010 19:18:25 -0700 (PDT), mynick <anglom...@yahoo.com>
>> wrote:
>>
>>
>>
>> >On Oct 18, 9:37 am, Jeff Liebermann <je...@cruzio.com> wrote:
>> >> On Mon, 18 Oct 2010 06:41:25 -0700 (PDT), mynick <anglom...@yahoo.com>
>> >> wrote:
>>
>> >> >if you test an OK varicapdiode with analog reistance meter what are
>> >> >you supposed to get?
>>
>> >> Avaricapis just an ordinary diode. When reverse biased, it acts as
>> >> a capacitor which varies with the applied reverse bias. It never
>> >> conducts current in the forward direction. Never... Ever...
>>
>> >> >Does it get hot/warm in battery powered
>> >> >transmitter
>>
>> >> No.
>>
>> >> >(if not than the element suspected to be a varactor and
>> >> >mounted to stick a little bit out of the transmitter box, could be
>> >> >an ic diode although it could not transmit trough walls, could it?)
>>
>> >> I have no idea. Perhaps it would be helpful if you would disclose:
>> >> 1. What are you trying to accomplish?
>> >> 2. What are you working on? (Make and model)?
>> >> 3. What have you done so far and what happen?
>> >this is a photo of the outdoor part of the wireless thermometer that
>> >stopped working
>> >http://img517.imageshack.us/img517/7053/img00331n.jpg
>>
>> Blurrrrrrry useless photo. Try again, this time with the camera set
>> to macro, and without the drastic tilt angle, which requires too much
>> depth of field.
>>
>> >checked discrete elements ok but no bias voltage at (varicap?)diode-
>> >that, kind of
>> >a transparent element, seen up front close to battery contacts having
>> >resistance in both directions od 6Kohms,
>> >any ideas?
>>
>> Nope. See my 3 questions.
>>
>> I've had far too much entertainment with wireless weather stations.
>> They don't seem to fail, but they do drift off frequency, or lose
>> power output due to moisture absorption in the PCB. I cheat and use a
>> spectrum analyzer to look at what it's sending. To the best of my
>> knowledge, most such remote thermometers do not use avaricap.
>> However, the humidity sensor is a polyimide or polystyrene capacitor,
>> with no case. The capacitor changes value as the dielectric absorbs
>> moisture and swells.
>>

>thanks
>the 'varicap' mentioned then might be a temp sensor(no humidity)
>as for frequency (589M says on the box)drift adjusting the screw near
>top of pic1 did not help

It's not a varicap. The thermometer element is either a thermistor,
or a semiconductor, such as an LM335:
<http://www.national.com/mpf/LM/LM335.html>
There are also thermometer chips that have the sensor inside:
<http://para.maxim-ic.com/en/results.mvp?fam=temp_sens>

>I wonder where is the antenna input
>please se
>http://img233.imageshack.us/img233/9038/img00333.jpg
>http://img6.imageshack.us/img6/9894/img00336q.jpg

The previous photo was blurry. These two are both blurry and too
small. Looks like you're using a Blackbery 8100 camera phone. Few
camera phones take decent closeup photos. Try using a real digital
camera with a "macro" setting.

See my 3 questions.

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

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

== 1 of 1 ==
Date: Sat, Oct 23 2010 9:17 pm
From: "John Fields"

"Brenda Ann" <newsgroups@fullspectrumradio.org> wrote in message
news:m6idndzQfMfjq1_RnZ2dnVY3go-dnZ2d@giganews.com...
>
>
> "nucleus" <rose122550@yahoo.com> wrote in message
> news:54849318-33dc-43b5-aabe-0a2c690cff86@k22g2000yqh.googlegroups.com...
>> for those who are energy conscious, the energy consumption of these
>> LCD TVs appear to be not only low but reversed:
>>
>> Sony Bravia 40 inch KDL-40EX401 --- 170 watts
>> Sony Bravia 52 inch KDL-52EX701 --- 142 watts
>>
>> i recently looked at the tags on back of these sets at Sams.
>
> 401: Standby mode: 0.19 W
> Shop mode: 146 W
> Home mode: 110 W
>
> 701: Standby mode: 0.16 W
> Home mode: 142 W
>
> Note: the 401 model is a standard LCD/Fluorescent backlight, while the 701
> model is an LCD/LED backlight, which is more efficient.
>
>

That's BS, Where do you get it from Punk?

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

== 1 of 3 ==
Date: Sat, Oct 23 2010 9:28 pm
From: mynick

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!)

== 2 of 3 ==
Date: Sat, Oct 23 2010 9:31 pm
From: "John Fields"

"mynick" <anglomont@yahoo.com> wrote in message
news:376a9249-e248-44a5-a135-36a535b21cf0@m7g2000yqm.googlegroups.com...
> 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!)

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.

== 3 of 3 ==
Date: Sat, Oct 23 2010 10:14 pm
From: Jeff Liebermann

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...

--
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

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