Oscilloscope Training Class (long)

Thread Starter

w2aew

Joined Jan 3, 2012
219
Which speaker were you? I thought the main speaker (I have only watched about half so far) was a Tek engineering (and I think you said you did not work for Tek).
I am the 2nd speaker. The class is started with a 15 minute introduction by Al Klase from the NJARC. Then, I take over the class for about 2 hours, followed by a 3rd speaker talking about the historical development of the CRT for scopes.

I'm not sure where you got the impression that I didn't work for Tek. In fact, I do work for Tek, since about 2006, after being a "customer" of Tek for 25+ years.

I'm sure you'll find that the videos on MY youtube channel have much better audio quality.
 

Thread Starter

w2aew

Joined Jan 3, 2012
219
Can you do one on digital scopes and required sample rate/bandwidth for the exact same circuit?
OK. I recorded one with two different digital scopes. The same video also answers a few other questions that folks asked me regarding the first video. Click here for the new video.

With regard to your question about the 2445. It is possible that a cleaning is in order for the delayed timebase switch. However, there may likely be a deeper problem. The service manual should provide you with some troubleshooting insight for the problem.

aw
 
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spinnaker

Joined Oct 29, 2009
7,815
I'm not sure where you got the impression that I didn't work for Tek. In fact, I do work for Tek, since about 2006, after being a "customer" of Tek for 25+ years.
I see now in your PM that says you DO work for Tek. I miss read it. That is why I am confused. :)
 
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spinnaker

Joined Oct 29, 2009
7,815
I have a couple of questions.

In the video you explain that the horizontal sweep is controlled by a sawtooth wave. Is that one transition of the sawtooth per sweep? The downward transition of the wave is where the trace is reset to the beginning?

What voltage level are you triggering on when setting the trigger. Is it the voltage level of the signal being measured?

Why were deflection plates used in scope tubes as opposed to the deflection yoke like in CRT monitors and TVs? Was it just for space or were there other reasons?
 

Thread Starter

w2aew

Joined Jan 3, 2012
219
I have a couple of questions.

In the video you explain that the horizontal sweep is controlled by a sawtooth wave. Is that one transition of the sawtooth per sweep? The downward transition of the wave is where the trace is reset to the beginning?

What voltage level are you triggering on when setting the trigger. Is it the voltage level of the signal being measured?

Why were deflection plates used in scope tubes as opposed to the deflection yoke like in CRT monitors and TVs? Was it just for space or were there other reasons?
Yes - the long up-slope is the horizontal drive, and then the fast down-slope is the retrace - which is the return of the beam back to the left side. Triggered sweep scopes turn off the beam during the retrace.

When setting the trigger, you are setting the relative (or sometimes absolute) voltage on the signal that is being used as the "Trigger Source". The trigger source signal is usually the signal that you are measuring, but you can set the source to a different channel or even the line voltage.

I believe that the electrostatic deflection was used (using plates) vs. magnetic deflection (using deflection coils like TV) mainly for bandwidth reasons. It would be very tough to drive deflection coils to the speeds required for a scope.
 

spinnaker

Joined Oct 29, 2009
7,815
Yes - the long up-slope is the horizontal drive, and then the fast down-slope is the retrace - which is the return of the beam back to the left side. Triggered sweep scopes turn off the beam during the retrace.

When setting the trigger, you are setting the relative (or sometimes absolute) voltage on the signal that is being used as the "Trigger Source". The trigger source signal is usually the signal that you are measuring, but you can set the source to a different channel or even the line voltage.

I believe that the electrostatic deflection was used (using plates) vs. magnetic deflection (using deflection coils like TV) mainly for bandwidth reasons. It would be very tough to drive deflection coils to the speeds required for a scope.
Ah yes retrace. That was the word I was thinking of. You don't hear that word much today in reference to video. :)

And yes I should have mentioned the trigger is in reference to the signal being used as the trigger.

Thanks for the clarification!
 

Thread Starter

w2aew

Joined Jan 3, 2012
219
Ah yes retrace. That was the word I was thinking of. You don't hear that word much today in reference to video. :)

And yes I should have mentioned the trigger is in reference to the signal being used as the trigger.

Thanks for the clarification!
I have a video specifically on the Trigger controls. If you are interested, click here.
 
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