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Phil Allison
Guest

Thu Aug 25, 2016 9:20 am   



Hi,

most of you know former regular on this NG, David L Jones, who reinvented himself as a video star with his EEVblog site. I stumbled on one of his many hundreds of blogs recently - please take a look.

https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/

The blog attempts to explode a "myth" about analogue and digital scopes in relation to display noise - particularly that DSOs are inherently noisier.

While I am not sure just what Dave is trying to prove, some of his assertions are very dubious.

The facts are that an analogue scope normally has a sharp trace revealing a great more detail of waveform being viewed. This is also a direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at all sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a thousand.

3. Absence of any artefacts due to sampling or quantising.


All this results in an accurate display of any continuous signal, including random noise. The clean trace shown on an analogue scope with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and bandwidth of 50MHz which has a calculated thermal noise of almost 1mV rms - with regular peaks over 4mV. The simple answer is that 1Mohm is in parallel with 20pF, so the impedance falls steadily from 8kHz onwards down to 160 ohms at 50MHz. Thermal noise is reduced by this to about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the blog is mainly due to quantising errors plus the discontinuous, vertical screen resolution of only 200 pixels in case of two of them. When the sampled value falls between pixels, random toggling occurs.

Lastly, when Dave turns up the brightness on his Tek 2225, you see the trace thicken ( due to mutual repulsion between electrons in the beam ) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which lights up when you do that revealing any imperfections in the plastic. He should have detached it.

Also when he uses the digital camera, the image becomes over exposed which again results in trace thickening. The story about "revealing missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems to contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk


..... Phil

Phil Allison
Guest

Fri Aug 26, 2016 5:53 am   



~misfit~ wrote:

Quote:

While I am not sure just what Dave is trying to prove, some of his
assertions are very dubious.


Indeed. For a while I managed to put up with his really annoying voice and
watched several of his videos trying to educate myself further. However he
talks so much shite and makes so many mistakes (sometimes fixing them with
text overlays afterwards or conceeding points in the comments section) that
I decided not to carry on torturing myself with his whine.


** Yes - unscripted presentations on video are usually tedious and often painful to watch. In that respect, Dave is not much worse than many others.

Thanks for the vote of confidence, but in the case of this vid Dave almost had me believing him for a few minutes. So much so, I experimented with my Rigol and BWD scopes to see if any of it was for real - finally convincing myself that it wasn't.

In any case, how unlikely would it be for Dave or anyone to come up with a fundamental truth about analogue scopes that has gone unnoticed for so long by millions of others ?

BTW:

Far as I can tell, no-one is manufacturing analogue scopes any more despite the fact that most agree they have unique capabilities when it comes to viewing analogue signals.

So I assume the manufacture of suitable CRTs and other essential parts has stopped too. Keeping the old ones going will become near impossible in the future.

This is not a good thing.



..... Phil

axolotyl
Guest

Fri Aug 26, 2016 7:30 am   



On 25-Aug-16 3:20 PM, Phil Allison wrote:
Quote:
Hi,

most of you know former regular on this NG, David L Jones, who reinvented himself as a video star with his EEVblog site. I stumbled on one of his many hundreds of blogs recently - please take a look.

https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/

The blog attempts to explode a "myth" about analogue and digital scopes in relation to display noise - particularly that DSOs are inherently noisier.

While I am not sure just what Dave is trying to prove, some of his assertions are very dubious.

The facts are that an analogue scope normally has a sharp trace revealing a great more detail of waveform being viewed. This is also a direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at all sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a thousand.

3. Absence of any artefacts due to sampling or quantising.


All this results in an accurate display of any continuous signal, including random noise. The clean trace shown on an analogue scope with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and bandwidth of 50MHz which has a calculated thermal noise of almost 1mV rms - with regular peaks over 4mV. The simple answer is that 1Mohm is in parallel with 20pF, so the impedance falls steadily from 8kHz onwards down to 160 ohms at 50MHz. Thermal noise is reduced by this to about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the blog is mainly due to quantising errors plus the discontinuous, vertical screen resolution of only 200 pixels in case of two of them. When the sampled value falls between pixels, random toggling occurs.

Lastly, when Dave turns up the brightness on his Tek 2225, you see the trace thicken ( due to mutual repulsion between electrons in the beam ) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which lights up when you do that revealing any imperfections in the plastic. He should have detached it.

Also when he uses the digital camera, the image becomes over exposed which again results in trace thickening. The story about "revealing missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems to contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk


.... Phil



At the end of the day he may make some mistakes (who doesn't) but to
give him credit he's build a large following and has probably
contributed quite a bit to folk learning more and doing more around
electronics. His forum is very active, aus.electronics is dead. :(



It seems odd that one would find fault and start a post on Usenet about it.

~misfit~
Guest

Fri Aug 26, 2016 7:30 am   



Once upon a time on usenet Phil Allison wrote:
Quote:
Hi,

most of you know former regular on this NG, David L Jones, who
reinvented himself as a video star with his EEVblog site. I stumbled
on one of his many hundreds of blogs recently - please take a look.

https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/

The blog attempts to explode a "myth" about analogue and digital
scopes in relation to display noise - particularly that DSOs are
inherently noisier.

While I am not sure just what Dave is trying to prove, some of his
assertions are very dubious.


Indeed. For a while I managed to put up with his really annoying voice and
watched several of his videos trying to educate myself further. However he
talks so much shite and makes so many mistakes (sometimes fixing them with
text overlays afterwards or conceeding points in the comments section) that
I decided not to carry on torturing myself with his whine.

Quote:
The facts are that an analogue scope normally has a sharp trace
revealing a great more detail of waveform being viewed. This is also
a direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at all
sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a
thousand.

3. Absence of any artefacts due to sampling or quantising.


All this results in an accurate display of any continuous signal,
including random noise. The clean trace shown on an analogue scope
with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and
bandwidth of 50MHz which has a calculated thermal noise of almost 1mV
rms - with regular peaks over 4mV. The simple answer is that 1Mohm is
in parallel with 20pF, so the impedance falls steadily from 8kHz
onwards down to 160 ohms at 50MHz. Thermal noise is reduced by this
to about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the blog
is mainly due to quantising errors plus the discontinuous, vertical
screen resolution of only 200 pixels in case of two of them. When the
sampled value falls between pixels, random toggling occurs.

Lastly, when Dave turns up the brightness on his Tek 2225, you see
the trace thicken ( due to mutual repulsion between electrons in the
beam ) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which
lights up when you do that revealing any imperfections in the
plastic. He should have detached it.

Also when he uses the digital camera, the image becomes over exposed
which again results in trace thickening. The story about "revealing
missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems to
contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk


I dare say that you're correct - my experience with EEV blog says you are. I
can't bring myself to listen to him long enough to check.
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

Phil Allison
Guest

Fri Aug 26, 2016 11:06 am   



axolotyl wrote:

Quote:
, Phil Allison wrote:
Hi,

most of you know former regular on this NG, David L Jones, who reinvented himself as a video star with his EEVblog site. I stumbled on one of his many hundreds of blogs recently - please take a look.

https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/

The blog attempts to explode a "myth" about analogue and digital scopes in relation to display noise - particularly that DSOs are inherently noisier.

While I am not sure just what Dave is trying to prove, some of his assertions are very dubious.

The facts are that an analogue scope normally has a sharp trace revealing a great more detail of waveform being viewed. This is also a direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at all sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a thousand..

3. Absence of any artefacts due to sampling or quantising.


All this results in an accurate display of any continuous signal, including random noise. The clean trace shown on an analogue scope with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and bandwidth of 50MHz which has a calculated thermal noise of almost 1mV rms - with regular peaks over 4mV. The simple answer is that 1Mohm is in parallel with 20pF, so the impedance falls steadily from 8kHz onwards down to 160 ohms at 50MHz. Thermal noise is reduced by this to about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the blog is mainly due to quantising errors plus the discontinuous, vertical screen resolution of only 200 pixels in case of two of them. When the sampled value falls between pixels, random toggling occurs.

Lastly, when Dave turns up the brightness on his Tek 2225, you see the trace thicken ( due to mutual repulsion between electrons in the beam ) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which lights up when you do that revealing any imperfections in the plastic. He should have detached it.

Also when he uses the digital camera, the image becomes over exposed which again results in trace thickening. The story about "revealing missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems to contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk




At the end of the day he may make some mistakes (who doesn't) but to
give him credit he's build a large following and has probably
contributed quite a bit to folk learning more and doing more around
electronics. His forum is very active, aus.electronics is dead. Sad


** AFAIK, EEVblog Forum posters are predominately Yanks and it's moderated by Dave himself as the "administrator".

At the moment, I have no great wish to join up and suspect I might even be barred anyhow. OTOH, David L. Jones can appear here any time he cares to.


> It seems odd that one would find fault and start a post on Usenet about it.

** Not odd at all, the topic itself is very interesting - Analogue V. Digital scope performance is red hot, debatable stuff these days.

BTW

Do I detect a hint of " I *heart* Dave " going on ??



..... Phil

Clocky
Guest

Fri Aug 26, 2016 2:15 pm   



On 26/08/2016 1:27 PM, axolotyl wrote:
Quote:
On 25-Aug-16 3:20 PM, Phil Allison wrote:
Hi,

most of you know former regular on this NG, David L Jones, who
reinvented himself as a video star with his EEVblog site. I stumbled
on one of his many hundreds of blogs recently - please take a look.

https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/


The blog attempts to explode a "myth" about analogue and digital
scopes in relation to display noise - particularly that DSOs are
inherently noisier.

While I am not sure just what Dave is trying to prove, some of his
assertions are very dubious.

The facts are that an analogue scope normally has a sharp trace
revealing a great more detail of waveform being viewed. This is also a
direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at all
sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a thousand.

3. Absence of any artefacts due to sampling or quantising.


All this results in an accurate display of any continuous signal,
including random noise. The clean trace shown on an analogue scope
with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and
bandwidth of 50MHz which has a calculated thermal noise of almost 1mV
rms - with regular peaks over 4mV. The simple answer is that 1Mohm is
in parallel with 20pF, so the impedance falls steadily from 8kHz
onwards down to 160 ohms at 50MHz. Thermal noise is reduced by this to
about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the blog is
mainly due to quantising errors plus the discontinuous, vertical
screen resolution of only 200 pixels in case of two of them. When the
sampled value falls between pixels, random toggling occurs.

Lastly, when Dave turns up the brightness on his Tek 2225, you see the
trace thicken ( due to mutual repulsion between electrons in the beam
) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which lights
up when you do that revealing any imperfections in the plastic. He
should have detached it.

Also when he uses the digital camera, the image becomes over exposed
which again results in trace thickening. The story about "revealing
missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems to
contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk


.... Phil



At the end of the day he may make some mistakes (who doesn't) but to
give him credit he's build a large following and has probably
contributed quite a bit to folk learning more and doing more around
electronics. His forum is very active, aus.electronics is dead. :(



It seems odd that one would find fault and start a post on Usenet about it.


You'd think he would take it up with Dave, he's quite open to discussion.

~misfit~
Guest

Fri Aug 26, 2016 2:49 pm   



Once upon a time on usenet Clocky wrote:
Quote:
On 26/08/2016 1:27 PM, axolotyl wrote:
On 25-Aug-16 3:20 PM, Phil Allison wrote:
Hi,

most of you know former regular on this NG, David L Jones, who
reinvented himself as a video star with his EEVblog site. I stumbled
on one of his many hundreds of blogs recently - please take a look.

https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/


The blog attempts to explode a "myth" about analogue and digital
scopes in relation to display noise - particularly that DSOs are
inherently noisier.

While I am not sure just what Dave is trying to prove, some of his
assertions are very dubious.

The facts are that an analogue scope normally has a sharp trace
revealing a great more detail of waveform being viewed. This is
also a direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at
all sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a
thousand. 3. Absence of any artefacts due to sampling or quantising.


All this results in an accurate display of any continuous signal,
including random noise. The clean trace shown on an analogue scope
with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and
bandwidth of 50MHz which has a calculated thermal noise of almost
1mV rms - with regular peaks over 4mV. The simple answer is that
1Mohm is in parallel with 20pF, so the impedance falls steadily
from 8kHz onwards down to 160 ohms at 50MHz. Thermal noise is
reduced by this to about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the blog
is mainly due to quantising errors plus the discontinuous, vertical
screen resolution of only 200 pixels in case of two of them. When
the sampled value falls between pixels, random toggling occurs.

Lastly, when Dave turns up the brightness on his Tek 2225, you see
the trace thicken ( due to mutual repulsion between electrons in
the beam ) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which
lights up when you do that revealing any imperfections in the
plastic. He should have detached it.

Also when he uses the digital camera, the image becomes over exposed
which again results in trace thickening. The story about "revealing
missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems to
contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk


.... Phil



At the end of the day he may make some mistakes (who doesn't) but to
give him credit he's build a large following and has probably
contributed quite a bit to folk learning more and doing more around
electronics. His forum is very active, aus.electronics is dead. :(



It seems odd that one would find fault and start a post on Usenet
about it.

You'd think he would take it up with Dave, he's quite open to
discussion.


It seemed to me like he was seeing if others thought there was substance to
his take on things first. Dave can be a bit OTT.
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

JW
Guest

Fri Aug 26, 2016 3:20 pm   



On Thu, 25 Aug 2016 20:53:38 -0700 (PDT) Phil Allison
<pallison49_at_gmail.com> wrote in Message id:
<cce8dac8-d669-49bf-ad3d-52429f60cfd6_at_googlegroups.com>:

>Far as I can tell, no-one is manufacturing analogue scopes any more despite the fact that most agree they have unique capabilities when it comes to viewing analogue signals.

These guys still do.
http://www.gwinstek.com/en-global/products/Oscilloscopes/Analog_Oscilloscopes/1

axolotyl
Guest

Fri Aug 26, 2016 5:01 pm   



On 26-Aug-16 5:06 PM, Phil Allison wrote:
Quote:
axolotyl wrote:

, Phil Allison wrote:
Hi,

most of you know former regular on this NG, David L Jones, who reinvented himself as a video star with his EEVblog site. I stumbled on one of his many hundreds of blogs recently - please take a look.

https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/

The blog attempts to explode a "myth" about analogue and digital scopes in relation to display noise - particularly that DSOs are inherently noisier.

While I am not sure just what Dave is trying to prove, some of his assertions are very dubious.

The facts are that an analogue scope normally has a sharp trace revealing a great more detail of waveform being viewed. This is also a direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at all sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a thousand.

3. Absence of any artefacts due to sampling or quantising.


All this results in an accurate display of any continuous signal, including random noise. The clean trace shown on an analogue scope with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and bandwidth of 50MHz which has a calculated thermal noise of almost 1mV rms - with regular peaks over 4mV. The simple answer is that 1Mohm is in parallel with 20pF, so the impedance falls steadily from 8kHz onwards down to 160 ohms at 50MHz. Thermal noise is reduced by this to about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the blog is mainly due to quantising errors plus the discontinuous, vertical screen resolution of only 200 pixels in case of two of them. When the sampled value falls between pixels, random toggling occurs.

Lastly, when Dave turns up the brightness on his Tek 2225, you see the trace thicken ( due to mutual repulsion between electrons in the beam ) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which lights up when you do that revealing any imperfections in the plastic. He should have detached it.

Also when he uses the digital camera, the image becomes over exposed which again results in trace thickening. The story about "revealing missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems to contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk




At the end of the day he may make some mistakes (who doesn't) but to
give him credit he's build a large following and has probably
contributed quite a bit to folk learning more and doing more around
electronics. His forum is very active, aus.electronics is dead. :(


** AFAIK, EEVblog Forum posters are predominately Yanks and it's moderated by Dave himself as the "administrator".


I haven't done a head count but the mix seems pretty even, plenty of
Aussies.

Quote:
At the moment, I have no great wish to join up and suspect I might even be barred anyhow. OTOH, David L. Jones can appear here any time he cares to.


Bah! Just create a nym.


Quote:
It seems odd that one would find fault and start a post on Usenet about it.

** Not odd at all, the topic itself is very interesting - Analogue V. Digital scope performance is red hot, debatable stuff these days.


I still keep my old Philips analog CRO around, it's good for some jobs.

Quote:

BTW

Do I detect a hint of " I *heart* Dave " going on ??


Not really he's entertaining and seems motivated by the right things.
My voice is like his, hence me not doing videos....


Quote:

.... Phil


Clocky
Guest

Fri Aug 26, 2016 8:19 pm   



On 26/08/2016 4:49 PM, ~misfit~ wrote:
Quote:
Once upon a time on usenet Clocky wrote:
On 26/08/2016 1:27 PM, axolotyl wrote:
On 25-Aug-16 3:20 PM, Phil Allison wrote:
Hi,

most of you know former regular on this NG, David L Jones, who
reinvented himself as a video star with his EEVblog site. I stumbled
on one of his many hundreds of blogs recently - please take a look.

https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/


The blog attempts to explode a "myth" about analogue and digital
scopes in relation to display noise - particularly that DSOs are
inherently noisier.

While I am not sure just what Dave is trying to prove, some of his
assertions are very dubious.

The facts are that an analogue scope normally has a sharp trace
revealing a great more detail of waveform being viewed. This is
also a direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at
all sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a
thousand. 3. Absence of any artefacts due to sampling or quantising.


All this results in an accurate display of any continuous signal,
including random noise. The clean trace shown on an analogue scope
with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and
bandwidth of 50MHz which has a calculated thermal noise of almost
1mV rms - with regular peaks over 4mV. The simple answer is that
1Mohm is in parallel with 20pF, so the impedance falls steadily
from 8kHz onwards down to 160 ohms at 50MHz. Thermal noise is
reduced by this to about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the blog
is mainly due to quantising errors plus the discontinuous, vertical
screen resolution of only 200 pixels in case of two of them. When
the sampled value falls between pixels, random toggling occurs.

Lastly, when Dave turns up the brightness on his Tek 2225, you see
the trace thicken ( due to mutual repulsion between electrons in
the beam ) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which
lights up when you do that revealing any imperfections in the
plastic. He should have detached it.

Also when he uses the digital camera, the image becomes over exposed
which again results in trace thickening. The story about "revealing
missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems to
contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk


.... Phil



At the end of the day he may make some mistakes (who doesn't) but to
give him credit he's build a large following and has probably
contributed quite a bit to folk learning more and doing more around
electronics. His forum is very active, aus.electronics is dead. :(



It seems odd that one would find fault and start a post on Usenet
about it.

You'd think he would take it up with Dave, he's quite open to
discussion.

It seemed to me like he was seeing if others thought there was substance to
his take on things first.


Yeah I guess that is fair enough, I wasn't really being critical but
just making the point that Dave is open to discussion unlike some people.

Dave can be a bit OTT.
>

No argument there. It's certainly a style that can grate but he makes no
apologies for it nor does he have to given his success.

Computer Nerd Kev
Guest

Sat Aug 27, 2016 3:09 am   



Phil Allison <pallison49_at_gmail.com> wrote:
Quote:
~misfit~ wrote:


While I am not sure just what Dave is trying to prove, some of his
assertions are very dubious.

Indeed. For a while I managed to put up with his really annoying voice and
watched several of his videos trying to educate myself further. However he
talks so much shite and makes so many mistakes (sometimes fixing them with
text overlays afterwards or conceeding points in the comments section) that
I decided not to carry on torturing myself with his whine.


** Yes - unscripted presentations on video are usually tedious and often
painful to watch. In that respect, Dave is not much worse than many others.


It's simply that his presentation style is more love or hate than most. I always
suspected that it appealed more to Americans, as they more often tend towards
exaggeration more than other major English speaking cultures. For me the result
is that I can quite enjoy similar videos by Mike Harrison (mikes electric stuff),
but I just can't hang in there with D. Jones.

It's similar to that American show on 7two called "Mysteries of the Underworld"
or something equally ridiculous. The places shown are often (though not always)
very interesting and historically informative, but the hyped up presentation
is so bad that I've never been able to sit through a whole one. At the same time
it's been going for a while now, so obviously a lot of people are drawn in by the
hype.

Give it a calm monotone commentary and excessively long cuts and I'd find it most
enjoyable, while 90% of the audience falls asleep.

Quote:
BTW:

Far as I can tell, no-one is manufacturing analogue scopes any more despite
the fact that most agree they have unique capabilities when it comes to
viewing analogue signals.

So I assume the manufacture of suitable CRTs and other essential parts has
stopped too. Keeping the old ones going will become near impossible in the
future.


I wouldn't be too worried. While a few will deliberately stick with CRTs, most
will continue along the eternal upgrade ritual and consider anything with a
deflection coil to be just lump of old junk. Hopefully the result will be that
lots of old CROs will be circulating for the same sort of price that would have
bought a replacement part back when they were available, and will do so for a
good few decades.

Consider how vintage television restorers still manage to find parts like CRTs
for their old 50s TVs.

--
__ __
#_ < |\| |< _#

Computer Nerd Kev
Guest

Sat Aug 27, 2016 3:12 am   



JW <none_at_dev.null> wrote:
Quote:
On Thu, 25 Aug 2016 20:53:38 -0700 (PDT) Phil Allison
pallison49_at_gmail.com> wrote in Message id:
cce8dac8-d669-49bf-ad3d-52429f60cfd6_at_googlegroups.com>:

Far as I can tell, no-one is manufacturing analogue scopes any more
despite the fact that most agree they have unique capabilities when
it comes to viewing analogue signals.

These guys still do.
http://www.gwinstek.com/en-global/products/Oscilloscopes/Analog_Oscilloscopes/1


There's always one.

They even have some Australian distributers:
http://www.rapid-tech.com.au/gwinstek_oscilloscopes.htm
http://www.ledaelectronics.com.au/gwinstek_oscilloscopes.htm

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Phil Allison
Guest

Sat Aug 27, 2016 4:30 am   



Computer Nerd Kev wrote:
Quote:



Far as I can tell, no-one is manufacturing analogue scopes any more despite
the fact that most agree they have unique capabilities when it comes to
viewing analogue signals.

So I assume the manufacture of suitable CRTs and other essential parts has
stopped too. Keeping the old ones going will become near impossible in the
future.

I wouldn't be too worried. While a few will deliberately stick with CRTs,
most will continue along the eternal upgrade ritual and consider anything
with a deflection coil to be just lump of old junk.



** Huh ??

There are no deflection coils inside an analogue scope - beam focusing and deflection is completely electrostatic.

FYI:

I can well understand colour LCD screens taking over for TV receivers - as there are almost no draw backs involved, only advantages.

The situation with scopes however is quite different, analogue and DSO instruments are not equivalent to each other.

All that has changed is that entry level DSOs, bristling with wiz-bang features, have recently dropped to a price less than that of a typical 20MHz analogue scope. Such DSOs are now easily the cheapest option and sales of analogue scopes has fallen to almost nil.

One of the biggest markets for new scopes is in education where the low price and extra measurement capabilities of DSOs mean they win the purchase contracts every time. The poor students get no say.

Do Tafes and Universities even teach analogue electronics any more ?

It hasn't gone away you know.


..... Phil

Computer Nerd Kev
Guest

Sat Aug 27, 2016 5:43 am   



Phil Allison <pallison49_at_gmail.com> wrote:
Quote:
Computer Nerd Kev wrote:


Far as I can tell, no-one is manufacturing analogue scopes any more despite
the fact that most agree they have unique capabilities when it comes to
viewing analogue signals.

So I assume the manufacture of suitable CRTs and other essential parts has
stopped too. Keeping the old ones going will become near impossible in the
future.

I wouldn't be too worried. While a few will deliberately stick with CRTs,
most will continue along the eternal upgrade ritual and consider anything
with a deflection coil to be just lump of old junk.

** Huh ??

There are no deflection coils inside an analogue scope - beam focusing and
deflection is completely electrostatic.


Sorry, I've spent more time looking at TV circuitry than CRO. Pretend I said
"anything that uses flying electrons".

Quote:
FYI:

I can well understand colour LCD screens taking over for TV receivers - as
there are almost no draw backs involved, only advantages.

The situation with scopes however is quite different, analogue and DSO
instruments are not equivalent to each other.

All that has changed is that entry level DSOs, bristling with wiz-bang features,
have recently dropped to a price less than that of a typical 20MHz analogue scope.
Such DSOs are now easily the cheapest option and sales of analogue scopes has
fallen to almost nil.

One of the biggest markets for new scopes is in education where the low price
and extra measurement capabilities of DSOs mean they win the purchase contracts
every time. The poor students get no say.

Do Tafes and Universities even teach analogue electronics any more ?


Well obviously they'd have to. However it may well have been dropped from
many courses where it's now thought that all you need to know is how to
program a microcontroller.

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~misfit~
Guest

Sat Aug 27, 2016 7:30 am   



Once upon a time on usenet Clocky wrote:
Quote:
On 26/08/2016 4:49 PM, ~misfit~ wrote:
Once upon a time on usenet Clocky wrote:
On 26/08/2016 1:27 PM, axolotyl wrote:
On 25-Aug-16 3:20 PM, Phil Allison wrote:
Hi,

most of you know former regular on this NG, David L Jones, who
reinvented himself as a video star with his EEVblog site. I
stumbled on one of his many hundreds of blogs recently - please
take a look.
https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/


The blog attempts to explode a "myth" about analogue and digital
scopes in relation to display noise - particularly that DSOs are
inherently noisier.

While I am not sure just what Dave is trying to prove, some of his
assertions are very dubious.

The facts are that an analogue scope normally has a sharp trace
revealing a great more detail of waveform being viewed. This is
also a direct result of having:

1. Constant bandwidth ( 20,50,100MHz ) plus the same rise time at
all sweep speeds.

2. Continuous vertical screen resolution of around 1 part in a
thousand. 3. Absence of any artefacts due to sampling or
quantising. All this results in an accurate display of any continuous
signal,
including random noise. The clean trace shown on an analogue scope
with no input is because there is no noise to be seen.

FYI: This might seem at odds with an input impedance of 1Mohm and
bandwidth of 50MHz which has a calculated thermal noise of almost
1mV rms - with regular peaks over 4mV. The simple answer is that
1Mohm is in parallel with 20pF, so the impedance falls steadily
from 8kHz onwards down to 160 ohms at 50MHz. Thermal noise is
reduced by this to about 15uV rms.

The random noise spiking seen in the traces of the DSOs in the
blog is mainly due to quantising errors plus the discontinuous,
vertical screen resolution of only 200 pixels in case of two of
them. When the sampled value falls between pixels, random
toggling occurs. Lastly, when Dave turns up the brightness on his Tek
2225, you see
the trace thicken ( due to mutual repulsion between electrons in
the beam ) and also some background pattern appears.

The background pattern is in the CRT's anti glare screen, which
lights up when you do that revealing any imperfections in the
plastic. He should have detached it.

Also when he uses the digital camera, the image becomes over
exposed which again results in trace thickening. The story about
"revealing missing noise" is a furphy.

BTW:

In the first few second of this blog on the Tek 2225, Dave seems
to contradict himself.

https://www.youtube.com/watch?v=8GR_6QH3uZk


.... Phil



At the end of the day he may make some mistakes (who doesn't) but
to give him credit he's build a large following and has probably
contributed quite a bit to folk learning more and doing more around
electronics. His forum is very active, aus.electronics is dead. :(



It seems odd that one would find fault and start a post on Usenet
about it.

You'd think he would take it up with Dave, he's quite open to
discussion.

It seemed to me like he was seeing if others thought there was
substance to his take on things first.

Yeah I guess that is fair enough, I wasn't really being critical but
just making the point that Dave is open to discussion unlike some
people.
Dave can be a bit OTT.

No argument there. It's certainly a style that can grate but he makes
no apologies for it nor does he have to given his success.


True. Just goes to show that one man's meat is indeed another mans poison.
<g>
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

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