OT - CRT's

[Jan Panteltje]

On a sunny day (Wed, 22 May 2019 08:43:38 -0700) it happened John Larkin
<jjlarkin@highlandtechnology.com> wrote in
<v4raee18f8uac197apud0e4vfjtqd106tn@4ax.com>:

On Wed, 22 May 2019 14:49:12 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:
Want to test some capacitors, ordered this from ebay yesterday:
https://www.ebay.com/itm/254207643325

Your fingers will add/change capacitance as you squeeze that.

Yes, and no,
yes because of course it will,
but no because I can zero too:
http://panteltje.com/panteltje/pic/lc_pic/
I use the LCP program I wrote for it,
and zero by simply pressing the spacebar.
So zero by pressing spacebar, grab C, let go of clip, read value.
Shoud work I hope.

My AADE meter came with a plug-in PC board that has a narrow gap in
the topside copper. I can zero the capacitance then bridge the gap
with a surface-mount cap, and push it down with the back end of a
wooden q-tip or a toothpick. That seems to be good for low-c caps.

I guess the real way to measure small caps would be to connect some
pcb pads to the meter, measure that, then solder in the cap and
measure again.

I could make a pc board to help doing that. Next proto board maybe.

Yes, OTOH for 10nF capacitors 1% is 100 pF and should not be a problem.

I have a little boxes full of Chinese SMD caps, but those came with caps in
unmarked plastic bags in the boxes, had some strange effect that if
I selected 47 pF measured frequency and then replaced it with 33 pF
then the frequency was lower...
So not sure China man put right bags in right boxes...
That sort of problems takes a lot of time to find.

 

John Larkin <jjlarkin@highlandtechnology.com> wrote in
news:53naeehdu1vkffma5grfn6ahg338h2f7ji@4ax.com:

On Wed, 22 May 2019 00:33:51 -0500, "Tim Williams"
tiwill@seventransistorlabs.com> wrote:

"whit3rd" <whit3rd@gmail.com> wrote in message
news:56bc7695-c7fe-4abc-9a14-b243cd975c62@googlegroups.com...
On Tuesday, May 21, 2019 at 5:11:33 PM UTC-7, John Larkin wrote:
On Tue, 21 May 2019 07:57:52 -0400, Bob Engelhardt
BobEngelhardt@comcast.net> wrote:

Is there still a use for CRT's?

No.

Yes. Lissajous figures, after all, depend on
vertical/horizontal matching, which an LCD
cannot provide, at rates that a 'video' screen cannot update.

That's an old-fashioned opinion even for a /newsgroup/. Lissajous
figures disappeared in the late 30s as synced/triggered sweep took
over. Combined with how not-very-useful they are, it strains the
imagination to believe anyone here has actually, usefully,
unironically used them. ;-)

Tim

When I was a kid, I'd set up a Lissajous display at parties. Yes,
I was a geek even then.

I took apart my first laser disc player, which happened to have a
HeNe laser and little optrical bench inside it, That bench had two
electrically "swingable" mirrors in it. I removed the prism
reflector, and sent a sine wave to one and music into the other, and
pointed the beam up at the ceiling. Cool stuff. Same wave into
both and WOW... Lissajous! Exciting as a kid.

 

John Larkin <jjlarkin@highlandtechnology.com> wrote in
news:ehmaeel82qggmpjtege9c6j0p35ll34pka@4ax.com:

On Tue, 21 May 2019 21:56:46 -0700 (PDT), whit3rd
whit3rd@gmail.com> wrote:

On Tuesday, May 21, 2019 at 9:15:20 PM UTC-7, Steve Wilson wrote:
whit3rd <whit3rd@gmail.com> wrote:

On Tuesday, May 21, 2019 at 5:11:33 PM UTC-7, John Larkin
wrote:
On Tue, 21 May 2019 07:57:52 -0400, Bob Engelhardt
BobEngelhardt@comcast.net> wrote:

Is there still a use for CRT's?

No.

Yes. Lissajous figure...

Everything that digital does for you, it also does TO you.

Lissajous figures require sine waves. Doesn't work with pulses,
square waves, etc.

Moden method: Display a few cycles of one signal, trigger on the
other. You can get much finer resolution than provided by
Lissajous figures, and track very small phase changes over hours
or days. You can measure the offset directly in picoseconds or
whatever is appropriate. This is difficult or impossible to do
with Lissajous figures.

The trigger is an ASYNCHRONOUS event, but its capture by a DSO is
typically a SYNCHRONOUS event, happening on a clock edge. That's
not good for accurate timing. Digtization hurts the process.

Our usual bench digital scopes can measure edge timings to 30
picoseconds, and the big LeCroy gets below 1 ps, with 1 ps RMS
jitter.

Look up "the sampling theorem." One can accurately measure times
to a very small fraction of the scope's sampling rate.

<https://hackaday.com/2015/02/10/the-one-million-dollar-scope-
teardown/>

 

[John Larkin]

On Wed, 22 May 2019 15:46:45 +0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

John Larkin <jjlarkin@highlandtechnology.com> wrote in
news:ehmaeel82qggmpjtege9c6j0p35ll34pka@4ax.com:

On Tue, 21 May 2019 21:56:46 -0700 (PDT), whit3rd
whit3rd@gmail.com> wrote:

On Tuesday, May 21, 2019 at 9:15:20 PM UTC-7, Steve Wilson wrote:
whit3rd <whit3rd@gmail.com> wrote:

On Tuesday, May 21, 2019 at 5:11:33 PM UTC-7, John Larkin
wrote:
On Tue, 21 May 2019 07:57:52 -0400, Bob Engelhardt
BobEngelhardt@comcast.net> wrote:

Is there still a use for CRT's?

No.

Yes. Lissajous figure...

Everything that digital does for you, it also does TO you.

Lissajous figures require sine waves. Doesn't work with pulses,
square waves, etc.

Moden method: Display a few cycles of one signal, trigger on the
other. You can get much finer resolution than provided by
Lissajous figures, and track very small phase changes over hours
or days. You can measure the offset directly in picoseconds or
whatever is appropriate. This is difficult or impossible to do
with Lissajous figures.

The trigger is an ASYNCHRONOUS event, but its capture by a DSO is
typically a SYNCHRONOUS event, happening on a clock edge. That's
not good for accurate timing. Digtization hurts the process.

Our usual bench digital scopes can measure edge timings to 30
picoseconds, and the big LeCroy gets below 1 ps, with 1 ps RMS
jitter.

Look up "the sampling theorem." One can accurately measure times
to a very small fraction of the scope's sampling rate.



https://hackaday.com/2015/02/10/the-one-million-dollar-scope-
teardown/

Which brings up an interesting point: people order expensive custom
SMA (or more exotic) hardline cables, change something, and then have
no use for those cables. So they are cheap on ebay.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Phil Allison]

Steve Wilson wrote:

Not many people make analog audio amplifiers these days.

** There is no other kind and millions are made each year.

Playing fast and loose with the facts is Steve's middle name.




...... Phil

 

On Wednesday, 22 May 2019 16:41:21 UTC+1, DecadentLinux...@decadence.org wrote:

tabbypurr wrote in
news:5db584f9-e973-4158-b4de-374f15c45950@googlegroups.com:
On Tuesday, 21 May 2019 12:58:13 UTC+1, Bob Engelhardt wrote:

Is there still a use for CRT's?

Collectors are one market of course. There's also testgear that
incorporated CRTs, other than silly scopes.

Finding replacements is the thing. They (lab gear) are typically NON
standard.

A good CRT maker still doing it is Thomas Electronics

https://www.thomaselectronics.com/

is anyone regunning tubes now that hawkeye has gone?


NT

 

[Phil Allison]

Tim Williams wrote:

Lissajous figures
disappeared in the late 30s as synced/triggered sweep took over.

** Complete bollocks.

Triggered sweep scopes did not come into common use until the 1950s.

Lissajous figures were popular into the 1990s and beyond.

Combined with how not-very-useful they are,

** Very useful when you need them.

it strains the imagination to believe
anyone here has actually, usefully, unironically used them. ;-)

** Typical bullshit laden Tim Williams post.



...... Phil

 

> So they are cheap on ebay.

Yup. Most of my proto stuff comes from eBay. Folks like Belden and Alpha charge several times what you can get equivalent wire and cable for on eBay. The retail price of RG-402 semi-rigid has gone through the roof, so eBay is a practical necessity.

Cheers

Phil Hobbs

 

[whit3rd]

On Wednesday, May 22, 2019 at 7:15:53 AM UTC-7, John Larkin wrote:

> A CRT can't really measure anything accurately.

No, not true; Earth's magnetic field, with a CRT that can be oriented in a variety of directions,
you get good results for magnitude and excellent results for direction. Few compasses
do as well.

The electron beam is a very fine field probe. I'm sensing that you aren't
keeping an open mind on the 'measure anything' issue.

 

[Chris Jones]

On 23/05/2019 00:57, Joerg wrote:

On 2019-05-21 04:57, Bob Engelhardt wrote:
Is there still a use for CRT's?


Yes, in oscilloscopes. There is stuff that cannot be properly detected
on a digital oscilloscope, especially when it comes to random noise from
sources whose noise pattern isn't known a priori. The jobs where you
have to see "fuzz on fuzz" and sometimes figure out a pattern in the
unwanted fuzz to find out where that comes from. Many times I have
dragged an old analog scope scope from a client's clutter cabinet, did a
quick emergency "resurrection" on it and found their problem. Other
times we did an EBay rush order for a Tektronix 2465 or similar.

You can still buy analog scopes, in part for the above reason. Iwatsu
makes high-end ones and lower cost versions can be found on Amazon.

https://www.iti.iwatsu.co.jp/en/products/ss/ss_top_e.html
It says no longer available :-(

https://www.amazon.com/dp/B00QXNY874
Gosh that is expensive.

 

Phil Allison <pallison49@gmail.com> wrote in news:2900c5cd-4b1e-
4d31-87ad-1c8714a65d2f@googlegroups.com:

Steve Wilson wrote:




Not many people make analog audio amplifiers these days.



** There is no other kind and millions are made each year.

Playing fast and loose with the facts is Steve's middle name.




..... Phil

I like that answer. There is no other kind. Any signal being
amplified, regardless of the waveform is essentially analog.

The gov boys use complex waveforms created in software defined
radio waveforms so the same amplifier can be used for multiple
communications links.

 

whit3rd <whit3rd@gmail.com> wrote in
news:c7754bf4-f446-4aff-a6b1-9c7a259da40d@googlegroups.com:

On Wednesday, May 22, 2019 at 7:15:53 AM UTC-7, John Larkin wrote:

A CRT can't really measure anything accurately.

No, not true; Earth's magnetic field, with a CRT that can be
oriented in a variety of directions, you get good results for
magnitude and excellent results for direction. Few compasses do
as well.

The electron beam is a very fine field probe. I'm sensing that
you aren't keeping an open mind on the 'measure anything' issue.

It is a known fact that an (some) upright video game screen gets
messed up depending on what direction the machine gets set up in.
The colors shift as does one of the frame scan characteristics.
Turn the machine and all goes away. The techs had to be careful not
to recalibrate the color outputs on the displays thinking they were
off, only to find out that he was working on the machine with it
turned the wrong way with respect to the Earth's magnetic field.

 

[John Larkin]

On Wed, 22 May 2019 16:28:59 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Wednesday, May 22, 2019 at 7:15:53 AM UTC-7, John Larkin wrote:

A CRT can't really measure anything accurately.

No, not true; Earth's magnetic field, with a CRT that can be oriented in a variety of directions,
you get good results for magnitude and excellent results for direction. Few compasses
do as well.

The electron beam is a very fine field probe. I'm sensing that you aren't
keeping an open mind on the 'measure anything' issue.

Does anyone use a CRT as a compass? That would be weird.

Fluxgates make really good compasses.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

On Thursday, 23 May 2019 00:40:16 UTC+1, DecadentLinux...@decadence.org wrote:

Phil Allison <pallison49@gmail.com> wrote in news:2900c5cd-4b1e-
4d31-87ad-1c8714a65d2f@googlegroups.com:
Steve Wilson wrote:

Not many people make analog audio amplifiers these days.

** There is no other kind and millions are made each year.

It certainly was a weird claim.

Playing fast and loose with the facts is Steve's middle name.

I like that answer. There is no other kind. Any signal being
amplified, regardless of the waveform is essentially analog.

Ah. So when a class D amp feeds its signal to the output pair to amplify it that's analogue amplification. And when an H bridge drives a motor with a rectangular wave, that's also analogue. And when a comparator amplifies a sensor's output, ditto. Now I understand. Than you for clarifying.


NT

 

tabbypurr@gmail.com wrote in
news:10f1b7ca-928c-4685-acb3-0d965c896c9e@googlegroups.com:

On Thursday, 23 May 2019 00:40:16 UTC+1,
DecadentLinux...@decadence.org wrote:
Phil Allison <pallison49@gmail.com> wrote in news:2900c5cd-4b1e-
4d31-87ad-1c8714a65d2f@googlegroups.com:
Steve Wilson wrote:

Not many people make analog audio amplifiers these days.

** There is no other kind and millions are made each year.

It certainly was a weird claim.

Playing fast and loose with the facts is Steve's middle name.

I like that answer. There is no other kind. Any signal being
amplified, regardless of the waveform is essentially analog.

Ah. So when a class D amp feeds its signal to the output pair to
amplify it that's analogue amplification. And when an H bridge
drives a motor with a rectangular wave, that's also analogue. And
when a comparator amplifies a sensor's output, ditto. Now I
understand. Than you for clarifying.


NT

How do you think an energized coil used for magnetic force
application "looks" at an incoming signal with a fast, high leading
edge slew rate?

How do you think the amp pushing it operates?

 

[Phil Allison]

tabb...@gmail.com wrote:

DecadentLinux...@decadence.org


I like that answer. There is no other kind. Any signal being
amplified, regardless of the waveform is essentially analog.

Ah. So when a class D amp feeds its signal to the output pair to amplify it that's analogue amplification. And when an H bridge drives a motor with a rectangular wave, that's also analogue. And when a comparator amplifies a sensor's output, ditto. Now I understand. Than you for clarifying.


NT

** Usual Nutcase Thornton smartarse bullshit that conveys NO information.

Yawnnnnnnnnnn....



..... Phil

 

[Phil Allison]

Bill Sloman wrote:

Phil Allison wrote:

** Usual Nutcase Thornton smartarse bullshit that conveys NO information.

Yawnnnnnnnnnn....


He is a reliable source of patronising non-information. When he does stoop to providing actual information he's less reliable.

** LOL !!



...... Phil

 

[Bill Sloman]

On Thursday, May 23, 2019 at 11:07:49 AM UTC+10, Phil Allison wrote:

tabb...@gmail.com wrote:

DecadentLinux...@decadence.org


I like that answer. There is no other kind. Any signal being
amplified, regardless of the waveform is essentially analog.

Ah. So when a class D amp feeds its signal to the output pair to amplify it that's analogue amplification. And when an H bridge drives a motor with a rectangular wave, that's also analogue. And when a comparator amplifies a sensor's output, ditto. Now I understand. Than you for clarifying.

** Usual Nutcase Thornton smartarse bullshit that conveys NO information.

Yawnnnnnnnnnn....

He is a reliable source of patronising non-information. When he does stoop to providing actual information he's less reliable.

--
Bill Sloman, Sydney

 

On Thursday, 23 May 2019 03:58:03 UTC+1, Bill Sloman wrote:

On Thursday, May 23, 2019 at 11:07:49 AM UTC+10, Phil Allison wrote:

** Usual Nutcase Thornton smartarse bullshit that conveys NO information.

Yawnnnnnnnnnn....

He is a reliable source of patronising non-information. When he does stoop to providing actual information he's less reliable.

now there's irony

 

[Jasen Betts]

On 2019-05-22, Chris Jones <lugnut808@spam.yahoo.com> wrote:

On 21/05/2019 21:57, Bob Engelhardt wrote:
Is there still a use for CRT's?

They collect radioactive dust (I think polonium that results from the
decay of radon) out of the air (it seems to be charged).

If you wipe the entire face of a CRT that has been used a lot recently,
with a tissue (preferably held in such a way that the dust all collects
in a small area of the tissue) then hold this dust in front of a geiger
counter, it will be quite noticably radioactive.

By collecting this radioactive dust out of the air, some of it will be
prevented from lodging in my lungs.

I suspect that the replacement of CRTs with LCDs in households will
eventually result in an increase in lung cancer, though probably only a
small one that may be masked by other changes over the years such as
vehicle emissions.

Also a reduction due to reduced exposure to ozone by not being near
CRTs, also radon isn't everywhere, moslty it's over granite.

--
When I tried casting out nines I made a hash of it.