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'LCD Osciloscope'
2000\04\06@172321 by mark templeman

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Does anyone know of any circuits for a reasonable quality
Oscilloscope based around an LCD graphics display

Regards

Mark Templeman

2000\04\06@173406 by smerchock, Steve

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part 0 2087 bytes
<P><FONT SIZE=2>Mark,</FONT>
</P>

<P><FONT SIZE=2>I know Velleman ( http://www.velleman.be ) makes a small O-SCOPE</FONT>
<BR><FONT SIZE=2>using a PIC16C65 and a 240x64 graphics LCD. I own one, </FONT>
<BR><FONT SIZE=2>works OK (especially lower frequencies). The users manual has</FONT>
<BR><FONT SIZE=2>the schematic in the back. You might beable to download it from</FONT>
<BR><FONT SIZE=2>their website. If not let me know and I'll dig mine out and </FONT>
<BR><FONT SIZE=2>make a copy and either EMAIL it or FAX it.</FONT>
</P>

<P><FONT SIZE=2>Best regards,</FONT>
<BR><FONT SIZE=2>Steve</FONT>
</P>
<BR>

<P><FONT SIZE=2>Steven Kosmerchock</FONT>
<BR><FONT SIZE=2>Father/Student/Engineering Technician</FONT>
<BR><FONT SIZE=2>http://www.geocities.com/researchtriangle/lab/6584 </FONT>
</P>

<P><FONT SIZE=2>&quot;Great spirits have always encountered violent </FONT>
<BR><FONT SIZE=2>oppposition from mediocre minds.&quot;--A.Einstein</FONT>
</P>

<P><FONT SIZE=2>{Original Message removed}

2000\04\06@174236 by David VanHorn

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At 10:11 PM 4/6/00 +0100, mark templeman wrote:
>Does anyone know of any circuits for a reasonable quality
>Oscilloscope based around an LCD graphics display

Tektronix new "digital phosphor" scopes.

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2000\04\07@082455 by Andrew Kunz

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TEK makes some really nice LCD scope.  I have the notebook-sized TDS-720, and I
love it.

Andy










mark templeman <spam_OUTmarktemplemanTakeThisOuTspamFSMAIL.NET> on 04/06/2000 05:11:20 PM

Please respond to pic microcontroller discussion list <.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU>








To:      PICLISTspamKILLspamMITVMA.MIT.EDU

cc:      (bcc: Andrew Kunz/TDI_NOTES)



Subject: LCD Osciloscope








Does anyone know of any circuits for a reasonable quality
Oscilloscope based around an LCD graphics display

Regards

Mark Templeman

2000\04\07@100845 by Wagner Lipnharski

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LCD technology is basically slow, so for high frequencies they are
forced to work with memory. The customer thinks it is an advantage to
have memory or delayed display, but in true there is no other way to do
that.  You can't possible "see" a 50 MHz signal in real time on a LCD
screen.  Steve, to mess with your words, I would change the phrase "OK
(specially lower frequencies)." to "OK (only in lower frequencies)"...
:)  In the high frequency real time world there is nothing that can
substitute (until now) the good and old CRT, I am wrong?
Wagner.

{Quote hidden}

2000\04\07@120639 by Don Hyde

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I've been using o-scopes for over 30 years, and feel kind of lost without
one around.  For most of that time, they've been analog because that was the
only kind available.

For the last year, I've been using one of the cute little Tek LCD scopes,
and I love it.  But sometimes you have to remember that it's not really the
same thing as an oscilloscope.  It's really an A/D converter, some memory,
and a display.  Sometimes they're equivalent, and sometimes they're not.

For digital signals, there's no way an analog scope can compete with a
storage scope for utility and ease of use.  Digital signals tend to be
one-shot things, or else have long sequences that don't repeat very often.
Storage of one-shot events and the ability to set a trigger that causes a 1
mS sample to be taken 100 mS later are incomparably better than trying to
get the event to repeat often enough to make a visible picture on an analog
scope.

For analog signals, you have to CLEARLY understand the fact that you are
looking at the output of an A/D converter with no anti-aliasing filter in
front of it.

For instance, if you have a digital o-scope that stores 1000 samples, and
you set up the horizontal display so that those 1000 samples represent 1 mS,
then you are looking at an A/D converter that's running at 1M
samples/second.  If you feed in a 1KHz sine wave, you will get a nice pretty
sine wave with one cycle across the screen.  If you feed in a 1,001,000 Hz
sine wave, you will get exactly the same picture on your screen, thanks to
aliasing.

> {Original Message removed}

2000\04\07@131603 by Dan Michaels

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Don Hyde wrote:
.....
>For instance, if you have a digital o-scope that stores 1000 samples, and
>you set up the horizontal display so that those 1000 samples represent 1 mS,
>then you are looking at an A/D converter that's running at 1M
>samples/second.  If you feed in a 1KHz sine wave, you will get a nice pretty
>sine wave with one cycle across the screen.  If you feed in a 1,001,000 Hz
>sine wave, you will get exactly the same picture on your screen, thanks to
>aliasing.

This is why, if you buy a d'scope, you want to look for one that has
a "glitch" or "envelope" feature, where you can push a button and quickly
see if aliasing is occurring. These features sample continuously at high
rate (say, 1 Msps) and display max/min over a period (say, 1 msec), rather
than just one sample every 1 msec.

Besides, with sampling, it's always a fun challenge to try to figure
out whether what you see is real or imaginary. [keeps those brain cells
clicking].
===================

Wagner Lipnharski wrote:
.....
 In the high frequency real time world there is nothing that can
>> substitute (until now) the good and old CRT, I am wrong?
>> Wagner.
>>

[Boy, you can always spot an old dyed-in-the-wool analog type].

Wagner, you're no doubt alluding to the fact that a sampling scope
would have to sample 10X or so per period of the "fastest" frequency
in a signal to produce a reasonably good "time-domain" reproduction.
Roughly speaking, the d-scope equivalent of a 100 Mhz a'scope would
have to sample at 500-1000 Msps. This is a real problem.

The difference is $800 -> $1000 for the a'scope and $5000 -> $10000+
for the equivalent d'scope. There are such things as sineX/X
reproduction of sampled signals which allow slightly slower sampling
rates, but the speed & complexity are still problems.

There are "CRT substitutes" today, from HP and Tek, etc, but they
sure ain't cheap.
================

Mark Templeman wrote:
.........
>> Does anyone know of any circuits for a reasonable quality
>> Oscilloscope based around an LCD graphics display

Steve Kosmerchock wrote:
....
>I know Velleman ( http://www.velleman.be ) makes a small O-SCOPE
>using a PIC16C65 and a 240x64 graphics LCD. I own one,
>works OK (especially lower frequencies). The users manual has
>

Jim Newton has references to this kind of project on Techref
somewhere. However, despite what Velleman and others call
"high-res" displays, their LCDs really have pretty poor
resolution for graphical data display. 128x64 pixels or so is
pretty bad, 320x128 is fair, but need to go higher (also more
$$$$) for good quality.

best regards,
- Dan Michaels
Oricom Technologies
http://www.sni.net/~oricom
==========================

2000\04\07@132617 by David VanHorn

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>Besides, with sampling, it's always a fun challenge to try to figure
>out whether what you see is real or imaginary. [keeps those brain cells
>clicking].

Besides, if you're clever, you can USE the aliasing :)

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2000\04\07@152423 by Dan Michaels

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David wrote:
.....
>>Besides, with sampling, it's always a fun challenge to try to figure
>>out whether what you see is real or imaginary. [keeps those brain cells
>>clicking].
>
>Besides, if you're clever, you can USE the aliasing :)
>

Right up until the 2nd wrap.

2000\04\07@194229 by briang

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In-Reply-To: <38EDE935.BC35C550spamspam_OUTustr.net>

Wagner Lipnharski <@spam@wagnerKILLspamspamUSTR.NET> wrote:
> LCD technology is basically slow, so for high frequencies they are
> forced to work with memory. The customer thinks it is an advantage to
> have memory or delayed display, but in true there is no other way to do
> that.  You can't possible "see" a 50 MHz signal in real time on a LCD
> screen.  Steve, to mess with your words, I would change the phrase "OK
> (specially lower frequencies)." to "OK (only in lower frequencies)"...
> :)  In the high frequency real time world there is nothing that can
> substitute (until now) the good and old CRT, I am wrong?

Wrong and very confused.

The LCD is only a display device it can be as slow as you like as long as the
circuit that's sampling the input signal and storing the readings in memory
goes fast that's all it takes.

Brian Gregory.
KILLspambriangKILLspamspamcix.co.uk

2000\04\07@200520 by Peter Schultz

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Wagner is right !!!!
You can have a tons of data captured pretty fast, if the display does not
let you update fast enough.
Did You ever try to see CD player eye-pattern signal ? You can clearly see
it with a 50 Mhz analog scope, but
my 100 MHz 1Gs/s Tektronix DSO can not display that signal at all.
Peter

{Original Message removed}

2000\04\07@205418 by Dan Michaels

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At 04:49 PM 4/17/00 -0700, you wrote:
>Wagner is right !!!!
>You can have a tons of data captured pretty fast, if the display does not
>let you update fast enough.
>Did You ever try to see CD player eye-pattern signal ? You can clearly see
>it with a 50 Mhz analog scope, but
>my 100 MHz 1Gs/s Tektronix DSO can not display that signal at all.
>Peter
>

Shoot, for YEARS, I've dreamed of, yearned for, and pined after a
1 Gs/s nirvana experience, and every Dec 25 raced downstairs like
a 6 YO hope-ing to find one under the tree, and now you go and tell
me they're just no darn good for real engineering problems. Wagner's
right, heck with digital, keep the old HP 1740, why mortgage the
house?

2000\04\08@003342 by Wagner Lipnharski

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hehe, why do you think I have one Tek2235 working at my house's bench
and another (backup) at the box with foam, humidity sensor and sylica
gel, dry ice, liquid nitrogen, and what else? ah, two dobermans and a
gard armed with a shotgun to protect it? :)  The Tek2465B (400MHz) is
the next in the wishing list ($1800), when and IF I could find one
affordable... nice all digital panel (you can store panel setups...
marvelous, marvelous), numeric digits for frequency, levels, and
everything else at the screen...
http://adams.prohosting.com/images/TEK-2465B.jpg

Ok, by around $250 you can buy a Tektronix 465 (2 x 100MHz) (piece of
resistance and magnific war tank robust unit) that if you turn power on
today, it will still working in 2040... check a picture of one:
http://web.meganet.net/n1yob/22403.JPG
another beauty:
http://adams.prohosting.com/images/TEK-465.jpg

here a nice digital panel 2245B (4 x 200MHz):
http://adams.prohosting.com/images/TEK-2445B-III.jpg

here a nice digital panel 2246A (4 x 100MHz):
http://adams.prohosting.com/images/TEK-2246A.jpg

Wagner

Dan Michaels wrote:
{Quote hidden}

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