MessageView 421F schematic

[Robert Baer]

Mik wrote:

Actually it's refered to as "knob and tube"
FYI

Robert Baer wrote:


HedgeWarden wrote:


Joe,

We had jitter problems in our monitors when we set them on top of a
power distribution box. That was back in the eighties, and people
don't use those power distribution boxes anymore, as far as I know.
(They had a "master" on/off switch, and switches for the system unit,
monitor, printer, and a few additional units. They were designed to
sit between the system unit, usually horizontal back then, and the
monitor.)

But the 60 Hz radiation from the box was too much for the monitor to
bear.

Any-ho, look for any electrical appliances near your monitor -
flourescent light, power strip, even an incandescent lamp.

It "may be" your building wiring. However, if the wiring uses cable
(hot and neutral in a common sheath) instead of separate wires at some
distance from each other (that predates even me - called "post and ??"
or something), it is unlikely to create much of a magnetic field very
far from the wires. More likely it is something much closer to the
monitor.

Here is a clue - if the wires to-and-from the appliance or circuit are
close together, the magnetic fields cancel each other a very short
distance from the wires. If the wires are separated by a distance, as
apparently they were inside the aforementioned box, they will radiate a
60 Hz magnetic field for some distance, potentially messing with that
delicate stream of electrons hurrying from the "guns" at the back of
the CRT to the precision phosphorescent dots on the face of the CRT.

-Howard

joe_macdonald25@yahoo.com wrote:


Hi all,

I have a bit of a strange problem. I have a fairly new, fairly high
quality 19" monitor that sometime suffers from an annoying "shake".
Usually it's most noticible in the upper left corner, but sometimes

it


occurs around the entire perimiter of the screen. I recently

connected


it to a SmartUPS 700, but the problem will still occur. I even
connected a 500 joules surge protector to the outlet which the UPS
connects to, but the problem STILL occurs. I've taken the monitor to
other locations and the problem does not happen. I live in an old
building (>75 yrs old), and I'm betting the wiring is also very old.
Things like turning on the washer/dryer set this off.

What else can I do to prevent this from happening? Is the APC

SmartUPS


700 simply not powerful enough to "condition" the line? I know the

UPS


works in terms of being able to keep my equipment online when there

is


no AC power, but it does not appear to be helping w/ preventing these
spikes/surges (correct terminology?) from reaching my monitor. For

my


own knowledge, why would this be the case?

Thanks for any insight...

joe.


FYI:
The older system is called "knob and post"; used until the late
1930's AFAIK.
************
AC power transformers near the monitor can also cause what is described.


"knob and post" might be another term...

 

[Mark Hansen]

On 4/4/2005 11:15, joe_macdonald25@yahoo.com wrote:

Hi all,

I have a bit of a strange problem. I have a fairly new, fairly high
quality 19" monitor that sometime suffers from an annoying "shake".
Usually it's most noticible in the upper left corner, but sometimes it
occurs around the entire perimiter of the screen. I recently connected
it to a SmartUPS 700, but the problem will still occur. I even
connected a 500 joules surge protector to the outlet which the UPS
connects to, but the problem STILL occurs. I've taken the monitor to
other locations and the problem does not happen. I live in an old
building (>75 yrs old), and I'm betting the wiring is also very old.
Things like turning on the washer/dryer set this off.

What else can I do to prevent this from happening? Is the APC SmartUPS
700 simply not powerful enough to "condition" the line? I know the UPS
works in terms of being able to keep my equipment online when there is
no AC power, but it does not appear to be helping w/ preventing these
spikes/surges (correct terminology?) from reaching my monitor. For my
own knowledge, why would this be the case?

Thanks for any insight...

joe.

I would look for an EM source bothering the monitor from the outside. For
example, having electrical devices sitting too close to the face of the
monitor. I have an electric pencil sharpener which, when activated, causes
a terrible shake on the display screen - and it's sits about two feet from
the monitor.

 

[Mark Jones]

Vidar Lřkken wrote:

Don Pearce wrote:

This experiment has nothing to do with cancellation in a room. Take
the speakers out of the pipe and try again. Use broadband noise as
your sound, and see what you can achieve by way of cancellation.
Mainly find out how far apart you can place the speakers and still
achieve useful results.


Well, I can't see how not. If you manage to place them according to the
noise, you should get the same effect, if using a DSP that calculates
the waveform, and timing.
Mercedes used this on some of their cars to cancel out noise, and many
planes use it...

And what happens when the listener changes position, say, rolls over or gets
out of bed? What if there are two listeners? Implant transmitters in their
craniums and track realtime position in 3D, adjust DSP to fit?

A pair of soft earplugs might be a -trifle- easier solution. Or better windows.
Or insulation. Or moving out of the 'hood and into the 'burbs, like the rest of
middle-class.

 

[Pooh Bear]

Vidar Lřkken wrote:

Don Pearce wrote:

This experiment has nothing to do with cancellation in a room. Take
the speakers out of the pipe and try again. Use broadband noise as
your sound, and see what you can achieve by way of cancellation.
Mainly find out how far apart you can place the speakers and still
achieve useful results.

Well, I can't see how not. If you manage to place them according to the
noise, you should get the same effect, if using a DSP that calculates
the waveform, and timing.

You can only do it for a single point in the room ( and even that's pushing
it ). Room reverberation and the indivual source locations make the concept
unrealisable.

Extra glazing by comparision works and is inexpensive.

Mercedes used this on some of their cars to cancel out noise,

A car cabin is a much smaller environment than a room. Some success can be
acheived. Lotus did a lot of early work on this but I don't think it ever
went into production. I have no idea why Mercedes bothered though. The
cabin in my Saab for comparison is so quiet that I find the 'tick' of the
brake light relay intrusive !

and many
planes use it...

They do ? You can get noise cancelling headsets ( easy to do ) but I'd like
to see a link to any further use.


Graham

 

[Mike Harrison]

On Sun, 10 Apr 2005 09:06:58 GMT, Robert Baer <robertbaer@earthlink.net> wrote:

kolotun@gmail.com wrote:
Robert Baer wrote:

kolotun@gmail.com wrote:

I would appreciate your opinions about the following device:

"Smart Tweezers LCR RCL RLC Meter Digital MultiMeter SMD"

I found on eBay. Looks like an interesting concept but is it as

good as

the seller tells?


Without a link, to look and evaluate????
Forgeddit!


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=25412&item=7506323975

1) For the size, Priority Mail Flat Rate is $3.85; the envelope could be
distorted more by adding padding. As long as one can fit something in
that envelope and seal it, there is no limit to the weight.
Theoretically, one could ship about 42 pounds of pure osmimum (the most
dense element known).
2) ?Five? digits? Forget it.
a) Impossible for capacitors and impractical as the best accuracy one
could possibly find in an SMD capacitor might be 5%. Stray capacitance
around the probe leads can add anything from 0.2pF to 5-10pF. The PCB,
the PCB traces, and all parts in parallel with the capacitor to be
?measured? can add another 2-20pF on strays alone.
b) Impossible for non-PCB resistors; maybe 3 digits for the low values
as the probe is *not* kelvin - and maybe 4 digits for higher values to a
few megs. If the resistors are on a PCB, then there are too many parts
that can be in parallel, and the reading can me orders of magnitude off.
c) Inductors: maybe 2 digits at best in a PCB environment. The stray
capacitances mentioned previously can royally mess up readings.
3) Parts sorting - Possible; 3 digits at most.
**
Now i see their specs; the best is 1%, which absolutely KILLs 5
digits and underscores my 3 digit statement above.

There is a difference between resolution and accuracy. Most DMMs have at least 1 more digit of
resolution than their accuracy spec. The extra digits can be useful for part matching, and
evaluation of tempcos and mechanical stability.
Nobody needs 5 digit accuracy on an LCR meter.

 

[mike]

kevinwile@hotmail.com wrote:

I have a TDR Pluser (Tek TU-5) but can't find any information on it's
use. Anyone?

Ask that question here:
http://groups.yahoo.com/group/TekScopes/messages

mike

--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
..
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Wanted 12" LCD for Compaq Armada 7770MT.
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

 

[Glenn]

Probably this just means that with the leads disconnected it finds no
device (infinite loss and an infinite noise figure).
Try hooking the input/output connections together to see if it tries to
measure it's own noise figure...

Glenn

kerlin wrote:

When I first turn on the meter I believ I should disconnect all leads
and then press the preset button. The displays should then show 30mhz
on the left hand side and Fdb on the right hand side. Mine show 30 mz
and E26. This is some kind od error message I guess. What could be the
prob and does anyone have a manual.
Thanks

 

[Robert Baer]

Mike Harrison wrote:

On Sun, 10 Apr 2005 09:06:58 GMT, Robert Baer <robertbaer@earthlink.net> wrote:


kolotun@gmail.com wrote:

Robert Baer wrote:


kolotun@gmail.com wrote:


I would appreciate your opinions about the following device:

"Smart Tweezers LCR RCL RLC Meter Digital MultiMeter SMD"

I found on eBay. Looks like an interesting concept but is it as

good as


the seller tells?


Without a link, to look and evaluate????
Forgeddit!


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=25412&item=7506323975


1) For the size, Priority Mail Flat Rate is $3.85; the envelope could be
distorted more by adding padding. As long as one can fit something in
that envelope and seal it, there is no limit to the weight.
Theoretically, one could ship about 42 pounds of pure osmimum (the most
dense element known).
2) ?Five? digits? Forget it.
a) Impossible for capacitors and impractical as the best accuracy one
could possibly find in an SMD capacitor might be 5%. Stray capacitance
around the probe leads can add anything from 0.2pF to 5-10pF. The PCB,
the PCB traces, and all parts in parallel with the capacitor to be
?measured? can add another 2-20pF on strays alone.
b) Impossible for non-PCB resistors; maybe 3 digits for the low values
as the probe is *not* kelvin - and maybe 4 digits for higher values to a
few megs. If the resistors are on a PCB, then there are too many parts
that can be in parallel, and the reading can me orders of magnitude off.
c) Inductors: maybe 2 digits at best in a PCB environment. The stray
capacitances mentioned previously can royally mess up readings.
3) Parts sorting - Possible; 3 digits at most.
**
Now i see their specs; the best is 1%, which absolutely KILLs 5
digits and underscores my 3 digit statement above.


There is a difference between resolution and accuracy. Most DMMs have at least 1 more digit of
resolution than their accuracy spec. The extra digits can be useful for part matching, and
evaluation of tempcos and mechanical stability.
Nobody needs 5 digit accuracy on an LCR meter.

Not true; most DMMs have an accuracy less than the digits.

A typical 3.5 digit DMM has +/- 0.5% +/- 1 digit (DC voltage, the
best scale).
A typical 4.5 digit DMM has +/- 0.1% +/- 3 digits (DC voltage, the
best scale).
The HP5326/27B (5.5 digits) has +/- 0.04% +/- 1 digit (DC voltage,
the worst scale, as it is made for measuring frequency or time).
The B&K 5492 (5.5 digits) has +/- 0.012% +/- 1 digit (DC voltage, the
best scale).

3 digits implies a possible 0.1% absolute best case; granularity
makes it worse.

The photo showed a falsely stable FIVE DIGITS!
Gee, maybe i can measure microns with a meter stick after all!

 

[Don Pearce]

On Wed, 06 Apr 2005 17:11:12 GMT, Vidar Lřkken <njus@vidarlo.net>
wrote:

Don Pearce wrote:

This experiment has nothing to do with cancellation in a room. Take
the speakers out of the pipe and try again. Use broadband noise as
your sound, and see what you can achieve by way of cancellation.
Mainly find out how far apart you can place the speakers and still
achieve useful results.

Well, I can't see how not. If you manage to place them according to the
noise, you should get the same effect, if using a DSP that calculates
the waveform, and timing.
Mercedes used this on some of their cars to cancel out noise, and many
planes use it...

Do the experiment. You will find out why. The stuff in cars and planes
works - barely - for two reasons.

1. The volume is very small
2. The frequencies being cancelled are very low

d

Pearce Consulting
http://www.pearce.uk.com

 

[Robert Baer]

Vidar Lřkken wrote:

Don Pearce wrote:

This experiment has nothing to do with cancellation in a room. Take
the speakers out of the pipe and try again. Use broadband noise as
your sound, and see what you can achieve by way of cancellation.
Mainly find out how far apart you can place the speakers and still
achieve useful results.


Well, I can't see how not. If you manage to place them according to the
noise, you should get the same effect, if using a DSP that calculates
the waveform, and timing.
Mercedes used this on some of their cars to cancel out noise, and many
planes use it...


Iffin eye 'member ritely, methinks i mentioned using DSPs (in opera

houses and other sound stages)...

 

[Rob Gaddi]

Jim wrote:

Hi,

I need to buy a small voltage constant current power supply. I'm
trying to decide on risking an ebay purchase for a used HP or spend
about the same for a new Mastech. The Mastech has a higher voltage
range that I could find useful.

Anyone own a Mastech? Did you ever have any problems? I've never
heard of 'em (the companies I worked for all used HP).


Thanks much!


Jim

We have a few Mastech HY1803Ds, picked them up for something like $70 a

pop. Been running them for around 6 months now with no problems.
Output ripple is next to non-existant, and none of my projects have
suffered any problems with them.

 

[Glenn]

Ah, that was it! Hook the leads together as I suggested and have it do a
calibration. That will fill the internal cal constants. As
113101.2243@compuserve.com suggested, if it happens again, the next time
you do a cold power-up, it means your batteries aren't keeping the data
alive when the instrument is off.

The Error is normal for the instrument before calibration (measurment of
itself). If it persists it means your battery is tired out.

Glenn

Error E26 means "internal attenuators not calibrated". You have just to
run at power on the cal routine. If cal constants are lost at the next
day turn on again errE26, the mem bat in the CPU is dead. Be very
careful : there was two models and one is rechargeagle, the other not
(it depends the ser nb)

 

[Yves Tardif]

I have service manual for Tek 2445. It is possible to send you via email if
you are interested. 3 zip files (5 meg each).

"joe4702" <joe4702@hotmail.com> a écrit dans le message de news:
1113704245.611111.174770@l41g2000cwc.googlegroups.com...

Hi,

I just purchased a Tek 2445A o'scope
for home hobby use and have two questions.

1) How do I activate the diagnostics? I'm use to
modern digital scopes at work where everything
is menu driven and pretty obvious.

2) When operating any of the controls, all of the
front panel LEDs flicker in unison. Is this
common or indicative of a serious problem?
Could it be dried out power supply caps?
Other than being an annoyance, does it affect
scope operation in a any way?

I'm in the process of ordering operating and
service manuals.

Any info would be appreciated.

Thanks much,
Joe

 

[John Musselman]

Taku,

E-mail me directly with some particulars and I'll check with some of the
suppliers I use regularly.

Quantity?
Technology: black and white/color, character/bitmap, etc.

I don't think they make them round but I'll ask the experts.

John Musselman

"taku" <thmushangi@yahoo.co.uk> wrote in message
news:f352abaa.0504181847.27856237@posting.google.com...

Hi
I was wondering if anyone knew if and where i could get round lcd
screens manufactured or possibly the price range if i could get
someone to manufacture it for me. I've been doing some research and
all the manufacturers seem to only build rectangular ones, but yet
i've seen at certain shows / awards that they sometimes use lcd/plasma
screens that are of a strange shape. I am looking for screens with a
radius of 15 inches.
Thanx

 

[OBones]

taku wrote:

Hi
I was wondering if anyone knew if and where i could get round lcd
screens manufactured or possibly the price range if i could get
someone to manufacture it for me. I've been doing some research and
all the manufacturers seem to only build rectangular ones, but yet
i've seen at certain shows / awards that they sometimes use lcd/plasma
screens that are of a strange shape. I am looking for screens with a
radius of 15 inches.

What if you were to use a rectangular one with a mask that only show a
round part of it?
Then your driving circuit only "draws" to the visible part and you're
sorted. That shouldn't be too hard to do, I would think.

 

[Dave Garnett]

"taku" <thmushangi@yahoo.co.uk> wrote in message
news:f352abaa.0504181847.27856237@posting.google.com...

Hi
I was wondering if anyone knew if and where i could get round lcd
screens manufactured or possibly the price range if i could get
someone to manufacture it for me. I've been doing some research and
all the manufacturers seem to only build rectangular ones, but yet
i've seen at certain shows / awards that they sometimes use lcd/plasma
screens that are of a strange shape. I am looking for screens with a
radius of 15 inches.
Thanx

15 inch Radius ? 30 inches diameter ? Thats pretty big ! AFAIK screens that
size get hand made at almost infinite cost.

What is the application ? What is your target price ? Is a larger pixel size
acceptable (say 1.5mm instead of 0.3mm) ?

For a one of, consider back projection

regards,
Dave




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[Dave Garnett]

"taku" <thmushangi@yahoo.co.uk> wrote in message
news:f352abaa.0504181847.27856237@posting.google.com...

Hi
I was wondering if anyone knew if and where i could get round lcd
screens manufactured or possibly the price range if i could get
someone to manufacture it for me. I've been doing some research and
all the manufacturers seem to only build rectangular ones, but yet
i've seen at certain shows / awards that they sometimes use lcd/plasma
screens that are of a strange shape. I am looking for screens with a
radius of 15 inches.
Thanx

15 inch Radius ? 30 inches diameter ? Thats pretty big ! AFAIK screens that
size get hand made at almost infinite cost.

What is the application ? What is your target price ? Is a larger pixel size
acceptable (say 1.5mm instead of 0.3mm) ?

For a one of, consider back projection

regards,
Dave




Posted Via Nuthinbutnews.Com Premium Usenet Newsgroup Services
----------------------------------------------------------
** SPEED ** RETENTION ** COMPLETION ** ANONYMITY **
----------------------------------------------------------
http://www.nuthinbutnews.com

 

[JW]

On Mon, 18 Apr 2005 20:42:23 -0700 "John Musselman" <fake@fake.org> wrote
in Message id: <u6%8e.483$2X2.104@okepread06>:

I don't think they make them round but I'll ask the experts.

http://www.geeks.com/pix/wootlp.htm

What use they'd be is anyone's guess.

 

[Grant Edwards]

On 2005-04-19, JW <none@dev.nul> wrote:

On Mon, 18 Apr 2005 20:42:23 -0700 "John Musselman" <fake@fake.org> wrote
in Message id: <u6%8e.483$2X2.104@okepread06>:

I don't think they make them round but I'll ask the experts.

http://www.geeks.com/pix/wootlp.htm

What use they'd be is anyone's guess.

I think this explains the primary use:

http://www.geeks.com/details.asp?invtid=ROUNDLCD

--
Grant Edwards grante Yow! Yow! It's some people
at inside the wall! This is
visi.com better than mopping!

 

[Casey]

JW said

"John Musselman" <fake@fake.org> wrote

I don't think they make them round but I'll ask the experts.

http://www.geeks.com/pix/wootlp.htm

What use they'd be is anyone's guess.

Might be great for testing the upcoming beta version of
Microsoft Portholes XP ....





Casey