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Author Topic: Test Equipment: Oscillocopes  (Read 100121 times)

TinselKoala

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Re: Test Equipment: Oscillocopes
« Reply #225 on: March 01, 2015, 01:15:24 AM »
No, I'd suggest you leave the +55 volt adjustment alone, until you go into the complete calibration procedure, which you probably don't need to do anyway.

The Astig control is easy to re-set if you change it for the worse and it's right there on the front panel. But again, I'd only mess with this if you actually see the "teardrop" dot in xy-mode when both channels are set to "ground" input coupling and the scope is fully warmed up, the dot is focused well, and the intensity is set to a reasonable, not overly bright level.

It is true that the mains-powered instruments are grounded back through the mains plug but it is not a good idea to depend on this for your signal ground path. (Even though it worked for the signal I was displaying on the LINE trigger video above... both the F43 and the scope are plugged into the same power strip and when I selected the non-isolated position on the FG it made the ground path connection through the ground prongs of the three-prong plugs and the power strip.) You should properly use short, direct paths for the signal ground just as you do for the signal itself.

The LINE trigger source setting is to see if you are experiencing some 60Hz hum, which might be due to improper grounding or high-resistance in the grounding. I suggested it because of the way the display was jumping up and down and seemed unstable otherwise in that video you posted.

The laptop's power supply will generally isolate the output to the laptop from the mains line plug, at least both of mine do. You can use your DMM to check continuity between the laptop-plug end and the mains cord prongs (unplugged of course!); I'll bet you do not have a proper path to the mains ground from the laptop's chassis through the power supply.

Yes, I think you will have to provide the proper ground connection to the laptop either way, whether the power supply is used or not, by clipping to the ground conductor of the headphone output jack which should be the outer collar, or to the USB jack's outer shield or similar chassis ground point. I just checked my laptops again and they are definitely _not_ grounded back to the mains through the power supplies. (an old IBM 600e and a newer Samsung netbook).

TinselKoala

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Re: Test Equipment: Oscillocopes
« Reply #226 on: March 01, 2015, 01:25:40 AM »
TK:

I am glad you noticed that the lettering was correct on Dave's digital scope.  I thought I saw that as well.  My new pc, if using the headphone jack on the front, disables the speakers of which I am running a total of 11 including a sub.  (All of my speakers except one pair have their own amps including a 100 watt/channel driving my 12" Cerwin Vegas in the living room.)  I can take or tap into one of the line outs on the back and still hear the music.

What the hell is a flac file?  I mean, I know what it is...I looked it up...but have not downloaded any program to open such a file.  I have used some of the choices given in the past and, my problem is, they take over every audio file and you have to use their program to play anything.  Should I just convert the youscope file to mp3?

I thought you would enjoy Dave's video on this.  He really had to manipulate that digital scope to get it to look right, and it still did not look as good, in my opinion, as the older model, ha ha.

Bill

Well, you can use VLC to play the FLAC file, and when you install it you can choose not to make it the default player for all media files.
http://www.videolan.org/vlc/#download
But once you get used to VLC you probably will use it for everything.

Pirate88179

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Re: Test Equipment: Oscillocopes
« Reply #227 on: March 01, 2015, 01:31:50 AM »
Well, you can use VLC to play the FLAC file, and when you install it you can choose not to make it the default player for all media files.
http://www.videolan.org/vlc/#download
But once you get used to VLC you probably will use it for everything.

VLC was one of the ones that took over my music collection.  It added little cone icons to every file.  I did not realize that I could stop it from doing so.  I will give it another try...thank you.

Bill

TinselKoala

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Re: Test Equipment: Oscillocopes
« Reply #228 on: March 01, 2015, 01:47:56 AM »
VLC was one of the ones that took over my music collection.  It added little cone icons to every file.  I did not realize that I could stop it from doing so.  I will give it another try...thank you.

Bill

hmmm... the last time I installed it, as I recall it gave a list of media file types and asked if you wanted to make it the default player for them, and showed checkboxes that you could uncheck for each file type extension. Now you've got me worried. I can't find where to change the file assignments now either. So maybe you can just find the right decoder for your favorite player to play the FLAC files instead of screwing up your system by installing VLC. Sorry.... I forget that my favorite solutions may not work for everyone sometimes.

Brian516

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Re: Test Equipment: Oscillocopes
« Reply #229 on: March 01, 2015, 01:50:27 AM »
WELP....

 ::)
Thanks TK for telling me to slow down, and PW for telling me to start back at square 1.  When I combined both pieces of advice, I solved the issue...

It appears that my PC wasn't actually disabling the enhancements when I was telling it to, for some reason or another. So it was the "Loudness Equalization" enhancement that was causing all the trouble.  I guess when I split up the HP jack and the main internal speakers, it disabled my ability to change those settings, even though it let me check/uncheck boxes and hit OK....  stupid computers.

https://www.youtube.com/watch?v=GKLZJ8hCClY
At 0:28 I say "microphone" when I meant Headphones.

Simple problem, simple fix.  Now to figure out WHY my laptop didn't change the HP settings with dual outputs enabled!! (or maybe it even had something to do with me shutting off the PC for a few min, and then powering it back on... who knows.... maybe I didn't restart after installing Soundcard Scope, and it froze my audio settings?
my bet is that it had something to do with the restart, and I won't be able to get it to freeze my settings again.)

Sooooooo..... NOW to see if I actually see the proper visuals for Youscope & Oscillofun!!! ANNDD  I can probably listen in, too!

Thanks for the always-good-advice, everyone!

Brian

I should have remembered this little trick from my PC repair/programming days..... if there's an issue and it involves a computer - RESTART THAT SUCKER FIRST!!!!  hahha

Brian516

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Re: Test Equipment: Oscillocopes
« Reply #230 on: March 01, 2015, 02:14:46 AM »
OscilloFUN!     8)

https://www.youtube.com/watch?v=YUlk-zwKfWo

Looks a whoooooole lot better now!
Hooked up a pair of old active PC speakers instead of the headphones, so you can actually hear it on the vid, too.

Other than being 90 degrees off, it looks like it should!

picowatt

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Re: Test Equipment: Oscillocopes
« Reply #231 on: March 01, 2015, 02:27:13 AM »
WELP....

 ::)
Thanks TK for telling me to slow down, and PW for telling me to start back at square 1.  When I combined both pieces of advice, I solved the issue...

It appears that my PC wasn't actually disabling the enhancements when I was telling it to, for some reason or another. So it was the "Loudness Equalization" enhancement that was causing all the trouble.  I guess when I split up the HP jack and the main internal speakers, it disabled my ability to change those settings, even though it let me check/uncheck boxes and hit OK....  stupid computers.

https://www.youtube.com/watch?v=GKLZJ8hCClY
At 0:28 I say "microphone" when I meant Headphones.

Simple problem, simple fix.  Now to figure out WHY my laptop didn't change the HP settings with dual outputs enabled!! (or maybe it even had something to do with me shutting off the PC for a few min, and then powering it back on... who knows.... maybe I didn't restart after installing Soundcard Scope, and it froze my audio settings?
my bet is that it had something to do with the restart, and I won't be able to get it to freeze my settings again.)

Sooooooo..... NOW to see if I actually see the proper visuals for Youscope & Oscillofun!!! ANNDD  I can probably listen in, too!

Thanks for the always-good-advice, everyone!

Brian

I should have remembered this little trick from my PC repair/programming days..... if there's an issue and it involves a computer - RESTART THAT SUCKER FIRST!!!!  hahha

Brian,

Looks like you are getting a stable display!!

It appears that you have stumbled upon one of the handy uses for a 1K square wave and a scope when doing audio testing.

A 1K square wave contains harmonics.  A perfect square wave would contain an infinite number of harmonics, but for audio work, we usually figure the leading edge of a 1K square wave will let us see out to 10K, and that a 2K square wave will let us see out to 20K.

If you feed a 1K or 2K square wave into an audio system and adjust its equalizer (tone controls) at various frequencies, you can rapidly tell if the equalizer is working.  For instance, a treble control when boosted, will create a peak at the leading edge of the square wave as the level of the higher frequency harmonics is increased (similar to the large peak at leading edge of the square wave in your video).  Cutting the treble control will cause the leading edge of the square wave to droop, or round, as the high frequency harmonics in the square wave are reduced.

A midrange tone control will produce a hump or dip in the middle of the square depending upon whether it is boosted or cut respectively.  A bass tone control will generally produce a left to right upward or downward slant of the square wave if boosted or cut respectively (sometimes you need to reduce the square wave to 100 to 500 Hertz to see the effects of a very LF equalizer that is centered at 50Hz or lower).

In your video, it looks like the high frequencies are being boosted quite a bit when your "enhancements" are turned on.  Any audio played thru that setting would sound VERY bright.

A "loudness" control typically boosts the bottom end (low frequencies) of an audio signal (as well as some upper mid boost).  Usually the lower the level control is set, the greater the bottom end is boosted when "loudness" is selected.  Your waveform looks more like just high frequencies and upper midrange are being boosted.  Possibly selecting a 100Hz square wave will allow you to see if the extreme LF is also being boosted, which would be indicated by the square wave tilting upward from left to right.   

Try to ensure that all EQ and "enhancements" are turned off when using the PC FG so that the waveforms will look correct (flat frequency response thru the soundcard).

I sure like seeing your waveform lock right up when you tweak the trigger level control.

You're getting there...

PW

TinselKoala

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Re: Test Equipment: Oscillocopes
« Reply #232 on: March 01, 2015, 02:59:53 AM »
OscilloFUN!     8)

https://www.youtube.com/watch?v=YUlk-zwKfWo

Looks a whoooooole lot better now!
Hooked up a pair of old active PC speakers instead of the headphones, so you can actually hear it on the vid, too.

Other than being 90 degrees off, it looks like it should!

That's great! It's actually one of the best displays of that file I've seen! This is actually the first time I've been able to see the full  A T O M D E L T A letters so clearly, even if they are upside down (instead of sideways?)  You could try inverting CH2 and see if the letters show right-side up!

Clearly there is nothing wrong with the major sections of the scope: input and display. I doubt that there will be any issues with timebase or trigger either.

You've got the L and R channels going to the wrong scope channels is all, just swap them and you'll see the display rotate 90 degrees to conform to what is usually seen. But before you do that try inverting CH2 !

TinselKoala

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Re: Test Equipment: Oscillocopes
« Reply #233 on: March 01, 2015, 03:15:46 AM »
Brian, in the earlier video you are puzzled by the fact that at one point the scope still showed a horizontal line when you had no signal from the laptop going to it. Later on, the screen blanked when you had no signal. What was the scope control that you adjusted between those incidents? The scope's Trigger Level control.  ;)
When it didn't blank, you had the trigger level set so precisely that it responded to the inevitable tiny noise left on the signal and showed you the baseline. Moving the control a tiny fraction either way would have caused the screen to blank. When you reset the trigger level later on, you didn't hit this exact setting, so when you turned off the signal from the soundcard the screen blanked as you expected it to. That all actually indicates _great_ trigger performance from a very sensitive trigger circuit.

 :D

picowatt

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Re: Test Equipment: Oscillocopes
« Reply #234 on: March 01, 2015, 03:26:46 AM »
Brian, in the earlier video you are puzzled by the fact that at one point the scope still showed a horizontal line when you had no signal from the laptop going to it. Later on, the screen blanked when you had no signal. What was the scope control that you adjusted between those incidents? The scope's Trigger Level control.  ;)
When it didn't blank, you had the trigger level set so precisely that it responded to the inevitable tiny noise left on the signal and showed you the baseline. Moving the control a tiny fraction either way would have caused the screen to blank. When you reset the trigger level later on, you didn't hit this exact setting, so when you turned off the signal from the soundcard the screen blanked as you expected it to. That all actually indicates _great_ trigger performance from a very sensitive trigger circuit.

 :D

TK,

Do you know if AUTO on Brian's TEK allows the scope to free run (display a trace) in the absence of a trigger (signal input)?

If so, he might be more comfortable using that mode instead of NORM.

PW


TinselKoala

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Re: Test Equipment: Oscillocopes
« Reply #235 on: March 01, 2015, 04:14:30 AM »
TK,

Do you know if AUTO on Brian's TEK allows the scope to free run (display a trace) in the absence of a trigger (signal input)?

If so, he might be more comfortable using that mode instead of NORM.

PW

Yes, I believe it does.


Meanwhile, scoposcopy fans... check out Jerobeam Fenderson's website. Scroll down about half-way. See anything familiar?    ;)

http://www.jerobeamfenderson.net/


Brian516

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Re: Test Equipment: Oscillocopes
« Reply #236 on: March 01, 2015, 05:07:01 AM »
PW,
that's most definitely good to know.  I'll remember that for the next time I set up an audio system.

That's great! It's actually one of the best displays of that file I've seen! This is actually the first time I've been able to see the full  A T O M D E L T A letters so clearly, even if they are upside down (instead of sideways?)  You could try inverting CH2 and see if the letters show right-side up!

Clearly there is nothing wrong with the major sections of the scope: input and display. I doubt that there will be any issues with timebase or trigger either.

You've got the L and R channels going to the wrong scope channels is all, just swap them and you'll see the display rotate 90 degrees to conform to what is usually seen. But before you do that try inverting CH2 !

I will most definitely try both right after I get this post typed up and see if I can get them to display right side up!  If I can, I'll make another vid of it.  I can actually make it look even sharper if I run it without an audio output.  Seems I got a good scope! Must have been very well taken care of by the power company that had it for a while, and then when they got rid of it, it was rarely ever used at all from what I was told.

Quote
Brian, in the earlier video you are puzzled by the fact that at one point the scope still showed a horizontal line when you had no signal from the laptop going to it. Later on, the screen blanked when you had no signal. What was the scope control that you adjusted between those incidents? The scope's Trigger Level control.  ;)
When it didn't blank, you had the trigger level set so precisely that it responded to the inevitable tiny noise left on the signal and showed you the baseline. Moving the control a tiny fraction either way would have caused the screen to blank. When you reset the trigger level later on, you didn't hit this exact setting, so when you turned off the signal from the soundcard the screen blanked as you expected it to. That all actually indicates _great_ trigger performance from a very sensitive trigger circuit.

Yep!  I realized that afterwards, and noticed that when the trigger is set in a certain range, it is EXTREMELY sensitive.  In that range, even lightly bumping the table, or setting something down will make it trigger.


Quote
TK,

Do you know if AUTO on Brian's TEK allows the scope to free run (display a trace) in the absence of a trigger (signal input)?

If so, he might be more comfortable using that mode instead of NORM.

PW

Yes, it most certainly does.  Isn't it a good idea to keep it on NORM and get used to adjusting the tigger level?  I'm sure there will also be some applications from time to time where I would want it on AUTO, so I will also set it on AUTO and repeat whatever process I had just done with it on NORM, that way I know what to expect with both.

Quote
Meanwhile, scoposcopy fans... check out Jerobeam Fenderson's website. Scroll down about half-way. See anything familiar?    ;)

http://www.jerobeamfenderson.net/

It's allllmost my scope!  that's the B model, though. Wonder what the difference is other than the button setup... looks like it's got a few extra knobs as well.

TinselKoala

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Re: Test Equipment: Oscillocopes
« Reply #237 on: March 01, 2015, 06:39:28 AM »
What I usually do is to use Auto to set up baselines (channel input coupling to Ground) and V/div settings (input coupling to DC or AC coupled) and trigger slope (rising or falling edge) , then once I know I can get the trace at the proper vertical scale, I switch to Normal and use the trigger level knob to get a triggered trace when the signal of interest is applied. Then when I'm not probing anything the screen blanks. When I apply the signal the screen wakes up and shows the trace.

Brian516

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Re: Test Equipment: Oscillocopes
« Reply #238 on: March 01, 2015, 06:50:38 AM »
That's great! It's actually one of the best displays of that file I've seen! This is actually the first time I've been able to see the full  A T O M D E L T A letters so clearly, even if they are upside down (instead of sideways?)  You could try inverting CH2 and see if the letters show right-side up!

Clearly there is nothing wrong with the major sections of the scope: input and display. I doubt that there will be any issues with timebase or trigger either.

You've got the L and R channels going to the wrong scope channels is all, just swap them and you'll see the display rotate 90 degrees to conform to what is usually seen. But before you do that try inverting CH2 !

!!!!!!!!!!!!!!!!!!!!!!!     :D

https://www.youtube.com/watch?v=bOPaevLfGnc

I am downloading Ubuntu ISO for the desktop, and decided to do a search for Linux Oscilloscope and Function Generator, and found this:

http://www.filebuzz.com/findsoftware/Linux_Function_Generator_Sound_Card/1.html

click on the Oscilloscope and read the features of that!   Not bad for $25, and the multiInstrument version has everything for $50.  I may try and get that at some point if I'm able to get 2 input channels going via soundcard, and don't end up finding something similar for free. That's after I get some real hardware of course...

Brian516

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Re: Test Equipment: Oscillocopes
« Reply #239 on: March 01, 2015, 06:52:20 AM »
What I usually do is to use Auto to set up baselines (channel input coupling to Ground) and V/div settings (input coupling to DC or AC coupled) and trigger slope (rising or falling edge) , then once I know I can get the trace at the proper vertical scale, I switch to Normal and use the trigger level knob to get a triggered trace when the signal of interest is applied. Then when I'm not probing anything the screen blanks. When I apply the signal the screen wakes up and shows the trace.

good stuff. I'll try to get in the habit of doing that.