MOTM

Hi everyone,

I finally got my hands on my first scope, and Owon color digital 
storage scope - dual channel, 25M bandwidth, sampling rate of 
100MS/s, and 6k points of record length per channel.  I'm like a kid 
in a candy store with this!  

So my question to the group is, is there anyone with lots of 
experience with using these cool devices that would be interested in 
guiding me a bit as I learn to use this thing?  The concentration 
would be how to use a scope to monitor and test MOTM modules.  My 
intention is to write a doc, to be posted here, for all of us scope 
newbies to learn from.  I would think that any assistance giving 
could be done primarily be email.  If anyone is interested, please 
contact me off-list.

I'm off to play with my new toy!  Gonna hook it to my MOTM-390 first!

Best Rgards,

Phil

> 
> Hi everyone,
> 
> I finally got my hands on my first scope, and Owon color digital=20
> storage scope - dual channel, 25M bandwidth, sampling rate of=20
> 100MS/s, and 6k points of record length per channel.  I'm like a kid=20
> in a candy store with this!=20=20
> 
> So my question to the group is, is there anyone with lots of=20
> experience with using these cool devices that would be interested in=20
> guiding me a bit as I learn to use this thing?  The concentration=20
> would be how to use a scope to monitor and test MOTM modules.  My=20
> intention is to write a doc, to be posted here, for all of us scope=20
> newbies to learn from.  I would think that any assistance giving=20
> could be done primarily be email.  If anyone is interested, please=20
> contact me off-list.
> 
> I'm off to play with my new toy!  Gonna hook it to my MOTM-390 first!
> 
> Best Rgards,
> 
> Phil

I'm in the same boat, having just gotten a used Tektronix for the same 
reasons just last month.

I spent an evening with it and got it to display the waveform of an
electronic tambura box (as fun to watch as it was to listen to), but it
was all trial-and-error.  Outside of a few obvious controls I found a lot
of the options mystifying, and that was before a skim through the manual
left me with as many questions as answers...

For example, is there a reference standard for calibrating these things?
Or should I just send a full-strength signal out of the modular and tweak
things until the waveform fills the screen?  Right now I'm not seeing
enough amplitude, and I'd rather keep an amplifier out of the input path
if I can.

Thanks for getting this ball rolling!
JN

----------------------- Tear Along Dotted Line -----------------------
John Neilson                                           jneil@...

    this message brought to you by 'e-mail' -- safe, clean, Modern!

On 24 Mar 2007, at 01:43, jneilyahoo@... wrote:

> For example, is there a reference standard for calibrating these  
> things?
> Or should I just send a full-strength signal out of the modular and  
> tweak
> things until the waveform fills the screen?  Right now I'm not seeing
> enough amplitude, and I'd rather keep an amplifier out of the input  
> path
> if I can.

I'll give this a try...

I usually keep the vertical scale at some calibrated value. A lot of  
scopes have a separate gain setting for each channel, separate from  
the V/div setting. I keep it at the default ('calibrated') setting,  
so that I can read off the waveform's amplitude from the screen.

Keep in mind that some probes have a 10:1 attenuation built in. If  
your scope has a 5 mV/div max sensitivity, this will become 50 mV/ 
div. Some scopes might show some noise (up to 0.2 or 0.4 div on your  
screen) on their most sensitive setting, so it is best to avoid this.

This makes it difficult to focus on low-level signals. Use a 1:1  
probe, or a switchable 10:1 / 1:1. However, you will need the 10:1  
probe if you need to measure on a high-impedance circuit. For the  
analog inputs and outputs a 1:1 probe will do just fine, and you can  
set your scope to something like 1 V/Div to start with.

It is kind of odd that you have trouble filling the scope's screen  
(if I understand you correctly) with the output of an MOTM module. It  
really shouldn't be a problem. Have you checked your probes?

With kind regards,
Ben

Go to www.tektronix.com and get their primer
XYZs of Oscilloscopes

It takes a bit to find it so here is a shortcut.
http://www.tek.com/Measurement/App_Notes/XYZs/03W_8605_2.pdf

Dave


--- In motm@yahoogroups.com, "Phil Peery" <ppeery@...> wrote:
>
> Hi everyone,
> 
> I finally got my hands on my first scope, and Owon color digital 
> storage scope - dual channel, 25M bandwidth, sampling rate of 
> 100MS/s, and 6k points of record length per channel.  I'm like a kid 
> in a candy store with this!  
> 
> So my question to the group is, is there anyone with lots of 
> experience with using these cool devices that would be interested in 
> guiding me a bit as I learn to use this thing?  The concentration 
> would be how to use a scope to monitor and test MOTM modules.  My 
> intention is to write a doc, to be posted here, for all of us scope 
> newbies to learn from.  I would think that any assistance giving 
> could be done primarily be email.  If anyone is interested, please 
> contact me off-list.
> 
> I'm off to play with my new toy!  Gonna hook it to my MOTM-390 
first!

> 
> Best Rgards,
> 
> Phil
>

A high quality probe is essential, and isn't necessarily included when 
you buy a 'scope.  You want a 10x probe if you're going to look at the 
internals of circuits, so as to minimize the loading effect of the 
probe, which becomes a part of the circuit and changes it to some 
degree.  If you've got two channels, you should use them, so you'll need 
two probes.  The purpose of looking at two signals is to view their 
relationship, triggering on one of them and seeing what the other is 
doing at the same points in time.

Become familiar with the triggering options and controls.  You normally 
want to use internal triggering from one of the two inputs.

When looking at a signal, switch around to a number of different 
frequency ranges, and tune the brightness down to get a clear, sharp 
image.  One of the most useful things you can discover with a scope 
looking at audio is ultrasonic high frequency oscillations (known as 
parasitics) riding on top of the main waveform.  You don't want these!  
They cause distortions of the bad kind (as opposed to the good sorts 
that we all love).  If you find parasitics and make changes to fix them 
(usually by adding a small capacitor in the feedback loop of an op amp), 
the scope tells you if your fix worked.  The scope opens up a world of 
visualization of what's happening.

I give another example.  I recently built a pair of CGS Tube VCA 
modules.  Looking at their output on my Veeblefetzer LED displays showed 
that the outputs were skewed into the negative voltage region.  I 
thought something was wrong, because the output is AC coupled.  I 
expected the signal to be centered.  A quick look with the scope showed 
what was going on.  The wave shape was a non-symmetrical pulse wave with 
the energy concentrated in the negative region.  Nothing was wrong.  The 
Veeblefetzers are great, but cannot show the detail a scope can.

-Richard Brewster
http://www.pugix.com

Ben Stuyts wrote:

> On 24 Mar 2007, at 01:43, jneilyahoo@... wrote:
>
>   
>> For example, is there a reference standard for calibrating these  
>> things?
>> Or should I just send a full-strength signal out of the modular and  
>> tweak
>> things until the waveform fills the screen?  Right now I'm not seeing
>> enough amplitude, and I'd rather keep an amplifier out of the input  
>> path
>> if I can.
>>     
>
> I'll give this a try...
>
> I usually keep the vertical scale at some calibrated value. A lot of  
> scopes have a separate gain setting for each channel, separate from  
> the V/div setting. I keep it at the default ('calibrated') setting,  
> so that I can read off the waveform's amplitude from the screen.
>
> Keep in mind that some probes have a 10:1 attenuation built in. If  
> your scope has a 5 mV/div max sensitivity, this will become 50 mV/ 
> div. Some scopes might show some noise (up to 0.2 or 0.4 div on your  
> screen) on their most sensitive setting, so it is best to avoid this.
>
> This makes it difficult to focus on low-level signals. Use a 1:1  
> probe, or a switchable 10:1 / 1:1. However, you will need the 10:1  
> probe if you need to measure on a high-impedance circuit. For the  
> analog inputs and outputs a 1:1 probe will do just fine, and you can  
> set your scope to something like 1 V/Div to start with.
>
> It is kind of odd that you have trouble filling the scope's screen  
> (if I understand you correctly) with the output of an MOTM module. It  
> really shouldn't be a problem. Have you checked your probes?
>
> With kind regards,
> Ben
>
>
>
>  
> Yahoo! Groups Links
>
>
>
>
>

> 
> Go to www.tektronix.com and get their primer
> XYZs of Oscilloscopes
> 
> It takes a bit to find it so here is a shortcut.
> http://www.tek.com/Measurement/App_Notes/XYZs/03W_8605_2.pdf
> 
> Dave
 
Oh, yeah, I was hoping something like this was out there somewhere!

I'll try to go through this before asking too many idiotic questions.*

Thanks!


*I'm not an electrical engineer, I just play an instrument that makes me
look like one.
----------------------- Tear Along Dotted Line -----------------------
John Neilson                                           jneil@...

    this message brought to you by 'e-mail' -- safe, clean, Modern!

Will and I are soon to be in the same boat - getting our scope soon. 
Thanks so much for this thread - we'll be listening attentively... if
you guys decide to take it offline, please include us, OK?  Thanks. 
Bill and Will




--- In motm@yahoogroups.com, jneilyahoo@... wrote:

>
> > 
> > Go to www.tektronix.com and get their primer
> > XYZs of Oscilloscopes
> > 
> > It takes a bit to find it so here is a shortcut.
> > http://www.tek.com/Measurement/App_Notes/XYZs/03W_8605_2.pdf
> > 
> > Dave
>  
> Oh, yeah, I was hoping something like this was out there somewhere!
> 
> I'll try to go through this before asking too many idiotic questions.*
> 
> Thanks!
> 
> 
> *I'm not an electrical engineer, I just play an instrument that makes me
> look like one.
> ----------------------- Tear Along Dotted Line -----------------------
> John Neilson                                           jneil@...
> 
>     this message brought to you by 'e-mail' -- safe, clean, Modern!
>

At 12:11 AM -0400 3/24/07, jneilyahoo@... wrote:
>*I'm not an electrical engineer, I just play an instrument that makes me
>look like one.

That's hilarious. Can we make t-shirts or something?


          Seth

Proud owner of a roughly-paperback-sized LCD scope, but still looking 
to pick up a Tektronix on eBay.

>  Proud owner of a roughly-paperback-sized LCD scope, but still looking
>  to pick up a Tektronix on eBay.

Don't know what you're after, but check this guy out:

http://www.users.qwest.net/~jbau/tstequip.htm

For example, it looks like he has a Tek 7623A 100 MHz storage scope for $165.

Doug

http://www.analognotes.com