Is this oscilloscope working nornally?

[Ricky Spartacus]

I`m new to oscilloscopes. Do all scope built the same when trying to
see a digital signal? If you look at these scopes at this website
below, you`ll find that the square waves on some scopes look normal
but others just a dash lines. Normal being that we see a rise
(vertical) line and a horizontal line when probing digital signals.

If you look at model 5020 you`ll see block of square wave but on 5020G
just dash lines. Is model 5020G scope not working properly? If not why
is it doing this?

http://www.minute-man.com/acatalog/Online_Catalog_Analog_Oscilloscopes_124.html

 

[Baphomet]

"Ricky Spartacus" <RickySpartan@mailandnews.com> wrote in message
news:d1e1d73f.0310170100.10157969@posting.google.com...

I`m new to oscilloscopes. Do all scope built the same when trying to
see a digital signal? If you look at these scopes at this website
below, you`ll find that the square waves on some scopes look normal
but others just a dash lines. Normal being that we see a rise
(vertical) line and a horizontal line when probing digital signals.

If you look at model 5020 you`ll see block of square wave but on 5020G
just dash lines. Is model 5020G scope not working properly? If not why
is it doing this?


http://www.minute-man.com/acatalog/Online_Catalog_Analog_Oscilloscopes_124.html

Normally, the criteria to see rise times is a good high frequency response.
I think that for optimal reproduction, the frequency response x the risetime
= .35 . I suspect that the problem you are seeing is more one of sloppy
photography than anything else because several of the higher frequency
scopes don't show the risetime whereas several of the lower frequency scopes
do. The horizontal or flat portion of the waveform is more indicative of a
good low frequency response, and I believe all of the scopes shown go down
to D.C.

 

[CFoley1064]

If you look at model 5020 you`ll see block of square wave but on 5020G
just dash lines. Is model 5020G scope not working properly? If not why
is it doing this?

Hi, Ricky. It's normal. You need very fast vertical deflection compared to
horizontal on digital signals. For analog scopes, you adjust the intensity of
the trace so it's comfortable. You can get better visualization of the rise
and fall, but you have to bump up intensity to the point that the slower,
"flat" parts are too bright and start to fuzz. Generally a tech will keep the
intensity turned down as low as is comfortable, because you want to avoid
phosphor "burn-in", you can get crisper lines, and jacking up the brightness
also puts more stress on the scope.

If you're interested in looking carefully at the digital signal's rise or fall,
you set the scope to trigger on + (rise) or - (fall), then expand the time base
to look closely. If you're just looking at digital signals, though, usually
you just assume it's a clean transistion unless you have reason to believe
otherwise. (It's also possible, since the 5020G has a built-in function
generator, they're trying to indirectly spin how clean the function generator
digital output is???)

I've owned a Gold Star scope similar to the 5020C for about 15 years
(out-of-town field service, needed an inexpensive low-end scope in a pinch),
and have _never_ had a problem with it. If you're looking for a low-end scope
to start out with, and you're on a limited budget but still want to buy new,
it's not a bad choice.

Good luck.
Chris

 

[Bullwinkle Jones]

I'm wondering what kind of signal the top trace on the first scope is, Ive
never seen anything like that before?

Ricky Spartacus wrote:

I`m new to oscilloscopes. Do all scope built the same when trying to
see a digital signal? If you look at these scopes at this website
below, you`ll find that the square waves on some scopes look normal
but others just a dash lines. Normal being that we see a rise
(vertical) line and a horizontal line when probing digital signals.

If you look at model 5020 you`ll see block of square wave but on 5020G
just dash lines. Is model 5020G scope not working properly? If not why
is it doing this?


http://www.minute-man.com/acatalog/Online_Catalog_Analog_Oscilloscopes_124.html

 

[Peter Bennett]

On Fri, 17 Oct 2003 10:07:30 -0700, "Bullwinkle Jones"
<DELETEMEbullwinkle_01_01@HERETOOhotmail.com> wrote:

I'm wondering what kind of signal the top trace on the first scope is, Ive
never seen anything like that before?


I think it might be a video "stairstep" signal, bit IIRC the standard

stairstep goes black to white, while that one is white to black. (but
it's been over 20 years since I worked in a TV studio)



--
Peter Bennett VE7CEI
GPS and NMEA info and programs: http://vancouver-webpages.com/peter/index.html
Newsgroup new user info: http://vancouver-webpages.com/nnq

 

[Dan Dunphy]

Ricky,
On dual channel, single beam scopes, there are 2 ways to get dual
trace. Alternate, and chop.
Alternate mode switches channel data on every sweep, so chanel 1 wil
be on every other sweep, with channel 2 in between. This is effective
on all but fairly slow sweep speeds, in where there is not enough
persistance to show both channels.
For this, you use chop, where the channel info switched back and forth
several to many times during a single sweep. It the chop speed is near
your sweep frequency, or a multiple of it, you will see a dashed
lines, which I think is what you are describing, and sometimes they
will walk across the screen, depending on the chop frequency relation
to the sweep frequency.
The pictures were too small to tell, in the link below.
If you can put your hands on the scope, simply switch modes and you
can determine what is going on.
Dan

lineOn 17 Oct 2003 02:00:50 -0700, RickySpartan@mailandnews.com
(Ricky Spartacus) wrote:

I`m new to oscilloscopes. Do all scope built the same when trying to
see a digital signal? If you look at these scopes at this website
below, you`ll find that the square waves on some scopes look normal
but others just a dash lines. Normal being that we see a rise
(vertical) line and a horizontal line when probing digital signals.

If you look at model 5020 you`ll see block of square wave but on 5020G
just dash lines. Is model 5020G scope not working properly? If not why
is it doing this?

http://www.minute-man.com/acatalog/Online_Catalog_Analog_Oscilloscopes_124.html

Colorado Springs, CO
My advice may be worth what you paid for it.

 

[Glenn Gundlach]

"Bullwinkle Jones" <DELETEMEbullwinkle_01_01@HERETOOhotmail.com> wrote in message news:<UoVjb.8309$f7.449163@localhost>...

I'm wondering what kind of signal the top trace on the first scope is, Ive
never seen anything like that before?

snip

Welcome to the world of analog video. That signal appears to be either
SMPTE color bars with subcarrier filtered off, or the 'Y' channel of
component
(Y, R-Y,B-Y) color bars. It is being displayed at horizontal line
rate. The time from sync pulse to sync pulse (the most negative
portion of that signal) should be 63.555555.... microseconds.

GG

 

[Baphomet]

"Bullwinkle Jones" <DELETEMEbullwinkle_01_01@HERETOOhotmail.com> wrote in
message news:UoVjb.8309$f7.449163@localhost...

I'm wondering what kind of signal the top trace on the first scope is, Ive
never seen anything like that before?

It looks like it's a dual channel two trace scope which I take to mean four
traces. It's really almost impossible (at least for me) to tell what they
are but the bottom looks like a quasi-square wave (it could even be in
chopped mode running at a high sweep speed looking like a square wave), and
the others might be a sawtooth, and a pulse. It's almost definitely not one
unique waveform.

 

[Baphomet]

"Ricky Spartacus" <RickySpartan@mailandnews.com> wrote in message
news:d1e1d73f.0310170100.10157969@posting.google.com...

I`m new to oscilloscopes. Do all scope built the same when trying to
see a digital signal? If you look at these scopes at this website
below, you`ll find that the square waves on some scopes look normal
but others just a dash lines. Normal being that we see a rise
(vertical) line and a horizontal line when probing digital signals.

If you look at model 5020 you`ll see block of square wave but on 5020G
just dash lines. Is model 5020G scope not working properly? If not why
is it doing this?


http://www.minute-man.com/acatalog/Online_Catalog_Analog_Oscilloscopes_124.html

Congratulations -

You have come up with the first Rorshach Test for electronics
http://www.deltabravo.net/custody/rorschach.htm