magnetic field

[John Larkin]

On Fri, 21 Jan 2005 09:58:51 GMT, Richard the Dreaded Libertarian
<eatmyshorts@doubleclick.net> wrote:

On Thu, 20 Jan 2005 16:30:04 -0800, John Larkin wrote:

On Thu, 20 Jan 2005 17:39:08 -0600, "jason" <jpop@carrollsweb.com
wrote:

Bush has the brain of a retarded clam.

He has a BS from Yale and a Masters from Harvard. He got better
grades than Kerry, and wasn't expelled for cheating like Teddy
Kennedy.

Where did you go to school?

Oh, his inauguration speech today was inspired, historical. He
explained what he's trying to do, and it's magnificent. Not easy, but
noble as all getout.

So, are you bowing down before his altar, and giving burnt offerings?

So, you're happy with half the world's population living under the
rule of thugs and leading short, miserable lives?

Yup, you probably are. After all, you've got yours.

John

 

[Rich Grise]

On Thu, 20 Jan 2005 08:42:31 +0000, John Woodgate wrote:

I read in sci.electronics.design that Tim Wescott
tim@wescottnospamdesign.com> wrote (in <10uuabeoom6vu1f@corp.supernews.
com&gt about 'Electronics employers in Toronto?', on Wed, 19 Jan 2005:

And for those of you who are still in school? Get an internship if at
all possible, or even a job as a stock clerk in your target industry.
Meet as many people as possible, keep track of them if they go someplace
else, and make sure folks know what you want to do when you get out.
Even as a stock clerk you can show drive and competence, which is a plus
when they interview you as well as a bunch of total unknowns.

I agree with this 100%. I did two spells of internship with the company
I wanted to join, and when I went for the employment interview, I'd
already worked for two of the board members. The fact that I had saved
them several thousand pounds (in 1957, when that was money) helped as
well.

Yeah, but this isn't really a fair comparison. You're one of the smart
ones. ;-)

Cheers!
Rich

 

[Allan Adler]

me <me@here.net> writes:

what were you doing reading the manual????

It's an old habit from using learning programming languages. I tried
to quit a couple of times, but it's really tough.

In this case, the device is an 8-in-3 multipurpose machine from
Harbor Freight, model 40102.
http://www.harborfreight.com

It arrives in a (cardboard box containing a) styrofoam box and is nearly
completely disassembled into almost 100 types of parts and this astonishingly
misleading manual is the only clue you get on how to put them together.
Some parts seem to be mislabeled and at least one part number seems
not to be represented. There is an exploded diagram of the box and
its contents in the manual, but due to aliasing errors, it is almost
impossible to use it to identify anything. Thus, even determining which
part numbers are represented has been a major undertaking.

On the other hand, it costs $200 (including S&H), which is cheap compared
with what lathes and milling machines cost, and even though it is clearly
just a toy, I think I'll be happy with it if I can just get it to work.
I've put together the jig saw and the wood lathe, but some details
of the metal lathe have me stumped, and there are several other
machines I still haven't built from the kit.

The main problem with the metal lathe is making sense of how one attaches
the tool to the cross slide. Otherwise, it is completely built.

In spite of these difficulties, I'm finding the experience pretty educational.

I can't post to rec.crafts.metalworking about it because:
(1) I am undoubtedly the only person on the group who has ever demeaned himself
to such an extent as to use this toy, hence people will be asking me about
it rather than the other way around.
(2) I promised that I wouldn't post to the group until I had built something,
however small or crappy. It seems that the long discussions I was having
in the hopes of getting a better set of inexpensive machine tools
provoked some judgmental heckling that made it necessary for me to
prove I was really interested in doing some metalworking. So, I'm
proving it. This is no reflection on rcm, which I think is one of
the best newsgroups in USENET by practically every standard I can
apply, and I'm looking forward to getting active in it again.
--
Ignorantly,
Allan Adler <ara@zurich.csail.mit.edu>
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.

 

[Tim Wescott]

Minus3db wrote:

Hello,

I'm a fairly recent graduate of EE, and I also have an electronics
tech. diploma under my belt. I'm *desperate* to find work in the
electronics industry, especially something in analog design, embedded
control, or RF engineering. I'm living in Toronto, Canada.

I'm having some real difficulty in finding a junior position - i.e.,
one that doesn't require 5-10 years of experience, or a Masters
degree. It's the old 'can't get the job without experience, can't get
the experience without a job' story. :-(
I've had lots of nice comments about my resume / cover letters, but
'we've hired someone else with more experience than you' is starting
to get old.
Going back to school is not an option for me, due to family
commitments.

Right now I'm working as a consultant for construction projects -
mostly low voltage distribution. Lots of drafting and paperwork, and
absolutely no exposure to electronics whatsoever, but it's paying the
bills for now. It's also driving me mad because I know exactly what
industry I want to work in, I just can't seem to get hired.

If anyone out there could offer some advice in finding a junior
position in the electronics industry, I'd be grateful. Right now, I'm
so disheartened that I'd even appreciate hearing from others in a
similar situation, just so I know that I'm not alone.

Thanks in advance,
minus3db@hotmail.com

1. Keep trying.
2. Get a copy of "What Color is your Parachute". More than half of it
is for finding the right career, but there's nice job finding bits in there.
3. Keep trying.
4. Find out if you have any friends, relations, fellow club members,
church members _whatever_ that work in the industry and _use the
connection_. I got my first job through a former girlfriend.
5. Keep trying.
6. Look for smaller companies, or companies who are hiring but not to
the position you want, or temp agencies. My first job wasn't the best
job -- I was wrenching on PC's for the most part, me with my MSEE, but I
got enough experience to apply for my _second_ job which was better, and
my _third_ job which lasted for almost 10 years and which I left to
start working independently (and my first job out of school turned into
my first customer out of 9-5 work).
7. Keep trying.

And for those of you who are still in school? Get an internship if at
all possible, or even a job as a stock clerk in your target industry.
Meet as many people as possible, keep track of them if they go someplace
else, and make sure folks know what you want to do when you get out.
Even as a stock clerk you can show drive and competence, which is a plus
when they interview you as well as a bunch of total unknowns.

Good luck.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Charles Edmondson]

Minus3db wrote:

Hello,

I'm a fairly recent graduate of EE, and I also have an electronics
tech. diploma under my belt. I'm *desperate* to find work in the
electronics industry, especially something in analog design, embedded
control, or RF engineering. I'm living in Toronto, Canada.

I'm having some real difficulty in finding a junior position - i.e.,
one that doesn't require 5-10 years of experience, or a Masters
degree. It's the old 'can't get the job without experience, can't get
the experience without a job' story. :-(
I've had lots of nice comments about my resume / cover letters, but
'we've hired someone else with more experience than you' is starting
to get old.
Going back to school is not an option for me, due to family
commitments.

Right now I'm working as a consultant for construction projects -
mostly low voltage distribution. Lots of drafting and paperwork, and
absolutely no exposure to electronics whatsoever, but it's paying the
bills for now. It's also driving me mad because I know exactly what
industry I want to work in, I just can't seem to get hired.

If anyone out there could offer some advice in finding a junior
position in the electronics industry, I'd be grateful. Right now, I'm
so disheartened that I'd even appreciate hearing from others in a
similar situation, just so I know that I'm not alone.

Thanks in advance,
minus3db@hotmail.com

Google around for the Ask the Headhunter site. He has some really good
advice for how to get hired, and how to survive the interview process.

If you know what you want, and you know who is doing it, then those are
the people to focus on. Talk to them. Talk to their sales folks. Talk
to their customer support. If they have products or development kits,
get them and learn how to use them!

--
Charlie
--
Edmondson Engineering
Unique Solutions to Unusual Problems

 

[Winfield Hill]

Tony Williams wrote...

In article <bj65u0prck12kkb1i4dliaf4a1knnh0r5p@4ax.com>,
Jim Thompson <thegreatone@example.com> wrote:

Come on, Tony, you done gone and ruined this whole thread by
introducing some actual engineering thought into the process ;-)

Sorry Jim.......

The folded cascode (with dc feedback bias) was my favorite
circuit when using a single jfet, it evades all sorts of
problems. By ratio'ing the currents it is even possible
to do the self-bias for constant gm, as per the Siliconix
app note TA70-2.

In this case, getting 29x off a 9Vdc rail is possible,
but still a little too marginal for comfort.

TA70-2 ==> Siliconix / Vishay AN102 From an old post by Tony,
"AN102 is obviously drawn from the original TA70-2 and seems
to be a 1997 update+rewrite in electronic form. The guts of
the information given in TA70-2 is still there, relatively
unchanged." http://www.vishay.com/docs/70595/70595.pdf


--
Thanks,
- Win

 

[Nicholas O. Lindan]

"Utthaman" <utthaman@gmail.com> wrote

Artificial Intelligence

I would like to see artificial strawberry jam
get perfected before I get excited about
artificial intelligence.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
To reply, remove spaces: n o lindan at ix . netcom . com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

 

[David Lesher]

James Meyer <jmeyer@nowhere.net> writes:

On Fri, 31 Dec 2004 14:56:31 -0800, artie <artie.m@gmail.com> wroth:

Been a while since I dealt with these beasties, and I'm operating under
the influence of OTC cold medication, but I seem to remember the
constant-voltage devices were saturated-core, and ran hot and noisy.

Ferroresonant transformers have terrible efficiencies. If you want to
double your power usage, they're great! Although Jim T's description of his
house seems to indicate that power usage is the least of his worries.

Indeed...A 1000 watt Sola draws ~350 watts at no load. It gets better
at full load, but that hum and heat come from somewhere. Be sure
and put it near your CRT monitor for most fun...

I second the CF suggestion; esp. since most offer free replacements.
Note the cheapest Home Despot ones will last a few days max in a
'top-hat' recessed fixture....you can guess how I know.

If you must waste heat with incandesents; a triac regulator would
be the best bet, I'd think. Maybe [cough] someone here would suggest
a design...

I've seen large servo driver Variac regulators, but that was 25
years ago and it was in a surplus store THEN...

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[David Lesher]

Jim Thompson <thegreatone@example.com> writes:

Good point. You're right, they almost always fail at turn-on.

If I recall accurately, Nela Park says that's hokum. It's a perception
issue; you always notice the ones that fail at turn-on....

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[David Lesher]

"Watson A.Name - \"Watt Sun, the Dark Remover\"" <NOSPAM@dslextreme.com> writes:

At work I've found this happens with three phase, and I've seen the
neutral wire carrying substantial current, especially when I measure the
current near areas where there is one or more copiers. They seem to
have a very high current draw at times, when the fuser comes on.

When HP-35's and such were first appearing; I read a story about a
building where HVAC motors, fluorescent lamps, elevators, and you
name it all failed regularly. Only clue was TI calculators would
regularly crash if plugged in.

After a large effort; turns out the Mini-sized (as in British car)
copier machine was putting nasty spikes on the line/neutral, nasty
enough to degrade motor insulation and other windings. They fitted
it with (!) lightning protection (Poly-phaser or such) and that
solved the issue. One wonders how ?Xerox? got UL approval....
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[Tony Williams]

In article <ct8fd602dna@drn.newsguy.com>,
Winfield Hill <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Where do you take the output? With JFET source follower from
the pnp output? Or from J1's gate signal for lower distortion?

Yes you are right, I missed that bit..... The signal across
R1 can be quite distorted, but the signal at J1's gate is
always quite good. There is the problem though that it is
only about 0.17V peak-peak. Perhaps the mod below would
develop more output swing off J1's gate.

,---------------------------------------+--- 9V
| |
\ \
/2k /1k5
\ \
_|_ 0.15mA approx, |
\_/ +--<------------------------------+ <--7V
| |/e so Rin= 180 ohms approx. |
+---|Q1,pnp | Id= 1.2mA
| |\ | Rd= 5k.
| | R2 R R |--+
| +--/\/\--+--/\/\--+--/\/\--+-->| J1, 2N3819
| | 135k | 150k | 150k | |--+
| | +| +| +| | <--5.3v
\ \R1 === === === |
/1k6 /15k | C | C | C |
\ \ +--------+--------+------+
| | |
| | |/e
+----------------------------------+--|Q2,pnp
| \_|_ |\
| ZD1 /_\ |
| 4v7 | +---->Vout
| | \
| | /3k3
| | \
| | |
0v--+----------------------------+---+--0v

There's enough headroom to squeeze a common-base pnp
underneath J1 and use J1's AC current swing to develop
Vout. That should produce about 1.8V pk-pk across a 3k3.

Moving the bottom of the 3x C's to J1-source avoids
the Gain degeneration caused by the 27/Ie of Q2.

--
Tony Williams.

 

[Mark Zenier]

In article <pan.2005.01.28.17.29.42.423374@example.net>,
Rich Grise <richgrise@example.net> wrote:

On Fri, 28 Jan 2005 15:15:23 +0000, David Lesher wrote:

And inside the microwave is a ferroresonant xfmr.....

It turns out, at least in the last one I took apart, it _looks_ like a
ferro, but that oil-filled cap is merely the filter cap in a half-wave
doubler. The tranny looks like a ferro, because the primary and secondary
are separate windings, with a space between them. But there are no shunts,
and no resonant winding. )-;

It's a linear transformer, and the cap is only a HV oil-filled cap.
The maggie _is_, however, the other diode in the half-wave doubler. ;-)

There are shunts (or some sort of welding trick), so that the transformer
current limits. It's like a Neon sign transformer.

Mark Zenier mzenier@eskimo.com Washington State resident

 

[Gary]

Malcolm Reeves wrote:

Hi,

My memory is playing tricks on me. I'm sure I read in a VCR manual
that its resolution was 312.5 lines (I'm in UK so 625 lines). I had
assumed this meant that VCR showed the same field twice in a frame to
save tape. But I can't find anything to say if they do or don't. All
I can find is that VCR tapes are 240/250 lines but I think that is
something different again.

TIA

All VCRs record both fields. If they didn't it would give picture
flicker on fast movement amongst other side effects.

The 240 line is the horizontal resolution.

Gary

 

[WEBPA]

There is a real good chance that it is not possible to do what you want without
re-wiring the headset. To work via a USB port, the headset must appear as an
active serial device. This is radically different from a the way microphones
and headphones work. In other words: It would take an active electronic device
to turn a USB headset into a microphone and headphone. Someone may well make
and market such a device, but it will not be a simple connector adaptor...and
it will probably require a separate power source.

I have a Logitech 300 USB headset/mic combo. It plugs into a USB port on my
computer.

Is there an adapter available that will adapt a USB plug to a standard 3.5mm
plug, so that the headsets can be used in non-USB applications such as a
standard audio-out jack? Thanks for the info!

webpa

 

[CWatters]

<colin_young@yahoo.com> wrote in message
news:1107309643.263922.231360@o13g2000cwo.googlegroups.com...

I'm trying to determine if it is possible to import a European
induction cooktop (hob in U.K. terminology) to the U.S. The main
difficulty appears to be the 50Hz/60Hz difference. Not surprisingly,
the manufacturers say it won't work, but I don't know if that is the
truth or if that's just what the sales people are told to say in order
to protect the American sales channel (since they don't sell them here,
and the 2 manufacturers who do cover the U.S. market are prohibitively
expensive).

I'm surprised as it's normally the other way around - prices cheaper in the
USA. Particularly given today's exchange rates. Are you looking for a
particular high cost model?

 

[CWatters]

"Michael" <NoSpam@att.net> wrote in message
news:42006AD3.5AFB72DE@att.net...

Are you certain it's a diode and not a fusing device? My coffee machine
had two of the latter in series with the heating element.

Yes sounds like a PTC fuse or similar.

 

[CWatters]

"x@nospam.com" <colin_young@yahoo.com> wrote in message
news:1107346695.931519.226640@g14g2000cwa.googlegroups.com...

$3000 and $4000 and AEG has I think 1 available for $3000.

In the U.K., one can routinely find Bosch and Siemens induction
cooktops for Ł500 to Ł800, which comes in around $1000 to $1500.

Ouch see what you mean.

.... perhaps try this site in CA. Has a 4 zone model for $ 1380 - $1600. See
"B180X"

http://www.cisolar.com/catExplorer2.html

Otherwise I'm not sure if 50Hz models will work on 60Hz. I found this site
that suggests the "high frequency" type are quite complex beasts.
http://www.jetro.go.jp/en/market/trend/market/docs/2004_11_mtm.html

Here's an idea though. I think some countries like Switzerland and Japan
have a mix of 50/60Hz. If their web sites ask which frequency you have then
it's a good bet that it matters.

http://www.gbaudio.co.uk/data/mains.htm

 

[Adam Aglionby]

So why are reverse phase dimmers/mosfet/igbt so rare?

Avolites had a prototype on their stand at PLASA a while back but the
production models went back to triacs.

Seem to remember there being a lot of wrangling about a major London
theatre installation of reverse phase dimmers that didn`t work as
intended, has the dust settled enough for anyone to say what the
problem was?

Thanks
Adam

 

[Clive Mitchell]

In message <1107468723.919105.137720@o13g2000cwo.googlegroups.com>, Adam
Aglionby <ledlight@gmail.com> writes

So why are reverse phase dimmers/mosfet/igbt so rare?

The circuitry is a bit more complex, particularly given the ease with
which a MOSFET/IGBT can be blootered. (Technical term for extreme
failure.)

Fundamentally I think the issue is with the sheer expense of developing
new RPC dimmers and the simple fact that most manufacturers are waiting
for their rivals to bring one out so that they can copy it's circuitry.

Meeeeeyow!

--
Clive Mitchell
http://www.bigclive.com

 

[Winfield Hill]

Tomi Holger Engdahl wrote...

The correct URL to this document is
http://www.epanorama.net/documents/lights/lightdimmer.html

It's also available without the epanorama.net header at
http://home2.planetinternet.be/gronsijn/ham/Schemas/Light%20dimmer%20circuits.htm

Tomi, I'm curious, who owns and operates the epanorama website, with
all your material on it? Who owns ELH Communications Ltd? Are you
personally involved? Who receives the webmaster@epanorama.net email?

Much of the epanorama.net material has the phrase, "Published by ELH
Communications Ltd., all rights reserved." How is material selected
for this designation, is it mostly your own stuff?


--
Thanks,
- Win