Date: Wed Oct 29 14:43:47 2008

Author: J. Terrence Klopcic

Subject: Re: oscilloscope renewal

Post:

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Steve,

Thanks for your input to my Tektronix problem.

Try this:

Set your trigger mode to NORMAL. Input a continuous signal since wave
or whatever) and lower your trigger level until you get a trace. Then
raise the trigger level above the highest signal and see if your screen
goes blank. Since you are no longer triggering - it should. Mine
doesn't; it retains the last trace - regardless of the Persistence
setting. (This behavior was confirmed by the tech folks at Tek.) As a
result, I can't use the presence of a trace in combination with
adjusting the trigger level to detect/select random signals above the
noise, a venerable practice for testing/setting radiation detectors.

Terry

* J. Terrence Klopcic, PhD
Director of Laboratories
Departments of Physics and Mathematics
Kenyon College*



Steve Anderson wrote:
>> On the subject of oscilloscopes.
>>
>> We have made a disappointing discovery in connection with our new
>> Tektronix digital oscilloscopes.
>
>
> We use the Tek 3012's, the next model up (this one also has better
> computer interface options).
> On these, the Persistence is default to Auto, but the time can be
> adjusted, or cleared (turned off).
> This is under the Display menu button. The default can be reset by
> saving a new set-up as default.
>
> My main complaint with these digital 'scopes is for doing Lissajous
> figures. You can do X-Y, but the sweep time makes an annoying
> "blanking" that obscures the pattern.
> (2:1 "infinity symbol" becomes two curves). The next model up, 4034
> also does this, but you can use slow waves and fast sweep to minimize it.
> I use an older HP or Tek 2221 analog/combo for this demo.
>
> we are doing the intro-to-scopes 209 lab today.
>
> Steve Anderson
> CSU Sonoma

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Steve,

Thanks for your input to my Tektronix problem.

Try this:

Set your trigger mode to NORMAL. Input a continuous signal since wave
or whatever) and lower your trigger level until you get a trace. Then
raise the trigger level above the highest signal and see if your screen
goes blank. Since you are no longer triggering - it should. Mine
doesn't; it retains the last trace - regardless of the Persistence
setting. (This behavior was confirmed by the tech folks at Tek.) As a
result, I can't use the presence of a trace in combination with
adjusting the trigger level to detect/select random signals above the
noise, a venerable practice for testing/setting radiation detectors.

Terry




J. Terrence Klopcic, PhD

Director of Laboratories

Departments of Physics and Mathematics

Kenyon College




Steve Anderson wrote:

On the subject of oscilloscopes.


We have made a disappointing discovery in connection with our new
Tektronix digital oscilloscopes.




We use the Tek 3012's, the next model up (this one also has better
computer interface options).

On these, the Persistence is default to Auto, but the time can be
adjusted, or cleared (turned off).

This is under the Display menu button. The default can be reset by
saving a new set-up as default.


My main complaint with these digital 'scopes is for doing Lissajous
figures. You can do X-Y, but the sweep time makes an annoying
"blanking" that obscures the pattern.

(2:1 "infinity symbol" becomes two curves). The next model up, 4034
also does this, but you can use slow waves and fast sweep to minimize
it.

I use an older HP or Tek 2221 analog/combo for this demo.


we are doing the intro-to-scopes 209 lab today.


Steve Anderson

CSU Sonoma





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