OT - CRT's

[John Larkin]

On Fri, 24 May 2019 15:56:51 +0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

John Larkin <jjlarkin@highlandtechnology.com> wrote in
news:gg2geepaj49b3p3138oovhs2gej52karjs@4ax.com:

On Wed, 22 May 2019 14:59:44 -0700 (PDT), Phil Allison
pallison49@gmail.com> wrote:

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 have a customer who wants us to make a 3-phase 400 Hz power
source to simulate a PM alternator. I was thinking we could buy
some already-built class-D amp boards to do the power bits, say
150 watts per channel or so. I'd rather buy than build that part.

We could use three of this eval board (we have a couple and they
work great) but they are big and have goofy connectors...

https://www.digikey.com/product-detail/en/texas-
instruments/TPA3255
EVM/296-46782-ND/7219409

Like most eval boards, it has a zillion jumper options.

Can anyone suggest a good-quality small equivalent class-D amp
board? We wouldn't want to use the really cheap ebay stuff which
might not be available next month.



Spin your own. Would not be much more than ebay jobs are. Quick
turn board houses are there for proto experimentation runs.

What you do is buy a couple cheap ebay jobs and use their design
ideas in making one of your own utilizing your years of experience
with compnonet placement thermal abatement, etc.

The base circuits are out there from cheap to perfectly and fully
conditioned and tuned.

And in your case, then you make three... one for each phase.

We could just crib the TI eval board circuit (that's what eval boards
are for) but that's still a project. Design, layout, assembly
drawings, BOM, test procedure, a zillion docs to release. I'd rather
buy something if it exists. Quantities will never be big here.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

John Larkin <jjlarkin@highlandtechnology.com> wrote in
news:gg2geepaj49b3p3138oovhs2gej52karjs@4ax.com:

On Wed, 22 May 2019 14:59:44 -0700 (PDT), Phil Allison
pallison49@gmail.com> wrote:

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 have a customer who wants us to make a 3-phase 400 Hz power
source to simulate a PM alternator. I was thinking we could buy
some already-built class-D amp boards to do the power bits, say
150 watts per channel or so. I'd rather buy than build that part.

We could use three of this eval board (we have a couple and they
work great) but they are big and have goofy connectors...

https://www.digikey.com/product-detail/en/texas-
instruments/TPA3255
EVM/296-46782-ND/7219409

Like most eval boards, it has a zillion jumper options.

Can anyone suggest a good-quality small equivalent class-D amp
board? We wouldn't want to use the really cheap ebay stuff which
might not be available next month.

Spin your own. Would not be much more than ebay jobs are. Quick
turn board houses are there for proto experimentation runs.

What you do is buy a couple cheap ebay jobs and use their design
ideas in making one of your own utilizing your years of experience
with compnonet placement thermal abatement, etc.

The base circuits are out there from cheap to perfectly and fully
conditioned and tuned.

And in your case, then you make three... one for each phase.

 

[Lasse Langwadt Christense]

fredag den 24. maj 2019 kl. 18.14.38 UTC+2 skrev John Larkin:

On Fri, 24 May 2019 15:56:51 +0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

John Larkin <jjlarkin@highlandtechnology.com> wrote in
news:gg2geepaj49b3p3138oovhs2gej52karjs@4ax.com:

On Wed, 22 May 2019 14:59:44 -0700 (PDT), Phil Allison
pallison49@gmail.com> wrote:

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 have a customer who wants us to make a 3-phase 400 Hz power
source to simulate a PM alternator. I was thinking we could buy
some already-built class-D amp boards to do the power bits, say
150 watts per channel or so. I'd rather buy than build that part.

We could use three of this eval board (we have a couple and they
work great) but they are big and have goofy connectors...

https://www.digikey.com/product-detail/en/texas-
instruments/TPA3255
EVM/296-46782-ND/7219409

Like most eval boards, it has a zillion jumper options.

Can anyone suggest a good-quality small equivalent class-D amp
board? We wouldn't want to use the really cheap ebay stuff which
might not be available next month.



Spin your own. Would not be much more than ebay jobs are. Quick
turn board houses are there for proto experimentation runs.

What you do is buy a couple cheap ebay jobs and use their design
ideas in making one of your own utilizing your years of experience
with compnonet placement thermal abatement, etc.

The base circuits are out there from cheap to perfectly and fully
conditioned and tuned.

And in your case, then you make three... one for each phase.

We could just crib the TI eval board circuit (that's what eval boards
are for) but that's still a project. Design, layout, assembly
drawings, BOM, test procedure, a zillion docs to release. I'd rather
buy something if it exists. Quantities will never be big here.

something here? https://www.profusionplc.com/type/class-d-amplifier-ic

some even include universal mains supply

 

On Tuesday, 21 May 2019 12:58:13 UTC+1, Bob Engelhardt wrote:
> Is there still a use for CRT's?

I'm surprised that some audiophool has not come up with a product that uses it (small scope tube) as an amplifying device. I'm tempted to submit an article to a hi-fi magazine for publishing next April.

 

On Friday, 24 May 2019 12:51:24 UTC+1, DecadentLinux...@decadence.org wrote:

John Larkin <jjlarkin@highland_snip_technology.com> wrote in
news:gmgeeepord0ncnlkv9isbi95vi58e8gc87@4ax.com:

And I have to confess that that scope HAS a CRT. It's a 50 GHz
digital sampling scope with a magnetic deflection (vertical scan!)
cathode ray tube.


It was my understanding that CRTs ALL have magnetic field beam
deflection... in both vectors.

CRT scopes are normally electrostatic. Early TVs were too.


NT

 

On Friday, 24 May 2019 21:15:02 UTC+1, grahamh...@graham65.plus.com wrote:

On Tuesday, 21 May 2019 12:58:13 UTC+1, Bob Engelhardt wrote:

Is there still a use for CRT's?

I'm surprised that some audiophool has not come up with a product that uses it (small scope tube) as an amplifying device. I'm tempted to submit an article to a hi-fi magazine for publishing next April.

With 3 guns it's almost a triple somethingode. The common anode is a bit of an issue So maybe a logic gate.


NT

 

>The  ONLY sense in which Mr Hobbs is correct is the electrostatic focus of the >electron beam may not be perfect at the edges of the CRT face. A trivial concern.

Which is why Mr Allison probably thinks that SEMs use electrostatic focusing.

Cheers

Phil Hobbs

 

[Gerhard Hoffmann]

Am 25.05.19 um 00:06 schrieb pcdhobbs@gmail.com:

There was also a tube with an electrostatically deflected sheet beam
and two anodes, used as a balanced modulator.

The 7360, possibly still the world's strongest mixer. I have a couple in the drawer that I've been meaning to use for something. Maybe I'll use a krytron and make an exploding-wire remote control doorbell.

Cheers

Phil Hobbs

Yes, made by RCA. I have a few, too. There is one in the
SSB balance modulator of my Yeasu FT505 shortwave transceiver.
It would have been much better to use it in the 2nd mixer.

I bought that in a previous life, as it seems now.
Maybe it still works, have not checked it for 30 years =:O

regards,
Gerhard

 

Hamamatsu made a tube-based sampling scope with optical input,
basically a streak tube with a slit and a PMT as output. I saw a demo
at the factory, but I don't think they ever commercialized it.

They did--it could do 1 ps/div, for only $100k. I had a purchase req for one turned down in late 2008 when DARPA canned the program that was going to fund my continuing tunnel junction optical communication project. (The program manager then tried to fund just us, but couldn't make it happen.)

Cheers

Phil Hobbs

 

[Phil Allison]

Phil Hobbs wrote:

It was my understanding that CRTs ALL have magnetic field beam
deflection... in both vectors.

Nope. Scopes are all-electrostatic. That's why they don't focus as
well as CRT TVs.

** That comment is massively ambiguous, same as a lot of Hobbs OTT comments.

Any decent scope has very fine trace, revealing waveform detail that makes any LCD screen scope look primitive.

Picture tubes use a raster system with limited vertical resolution, again visible waveform detail is not in the same league as a CRT scope. If the image is colour, convergence is never perfects.

The ONLY sense in which Mr Hobbs is correct is the electrostatic focus of the electron beam may not be perfect at the edges of the CRT face. A trivial concern.



..... Phil

 

No, but I have a couple of the extension cables, which are still rare
and expensive. It's great to get the sampling head a few inches from
the signal source.

Yup, I have two of the 2-m ones too, and as you say, they're dead useful. I even found one each of the SD-46 and SD-48 20 and 30 GHz O-E converters for fairly cheap. Ebay saved searches and patience, man.

Cheers

Phil Hobbs

 

There was also a tube with an electrostatically deflected sheet beam
and two anodes, used as a balanced modulator.

The 7360, possibly still the world's strongest mixer. I have a couple in the drawer that I've been meaning to use for something. Maybe I'll use a krytron and make an exploding-wire remote control doorbell.

Cheers

Phil Hobbs

 

[Joerg]

On 2019-05-23 17:47, Phil Hobbs wrote:

On 5/23/19 11:09 AM, Joerg wrote:
On 2019-05-22 16:39, Chris Jones wrote:

[...]

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


Well, you can get cheaper ones:

https://www.amazon.com/Sinometer-Single-Channel-Oscilloscope-CQ5010C/dp/B00NB58FJE/



I have three Tek analogue scopes: the 475A and 2467 work, and the 466
storage scope doesn't. Fifteen or so years ago, I used to use a 2465A
quite a lot, but these days I mostly use DSOs. (*)

I still really like the 246x's triggering.

The trigger in that series is unsurpassed. What is absolutely not cool
is the delayed-trigger clutch. It is an undersized piece of fairly
brittle plastic behind the front panel and one sunny day it happened at
a client ... crack. To my surprise there was a guy in Greece who made
and sold a nearly complete set of new front panel plastic parts.
Installing all that took almost an hour but then the client had a scope
good as new. While waiting for the stuff I could coax it into delayed
trigger by operating the slide switch behind the panel with a bent wire
hook.

Cheers

Phil Hobbs

(*) a couple of TDS 784As (1 GHz 4GS/s), a TDS 694C (3 GHz 10 Gs/s), and
two 1180x sampling scope mainframes with about 20 plug-ins. Magic.

Those sampling scope mainframes are tempting but I just don't have the
space. Since I am gradually retiring it would also be hard to justify
the expense in front of SWMBO, especially now that I might need to buy a
new road bike.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[John Larkin]

On Fri, 24 May 2019 13:14:58 -0700 (PDT),
grahamholloway@graham65.plus.com wrote:

On Tuesday, 21 May 2019 12:58:13 UTC+1, Bob Engelhardt wrote:
Is there still a use for CRT's?

I'm surprised that some audiophool has not come up with a product that uses it (small scope tube) as an amplifying device. I'm tempted to submit an article to a hi-fi magazine for publishing next April.

My high school science project was "The Cathode-Ray Tube as an Active
Circuit Element." I made it to the National Science Fair in Baltimore
and we got a tour of the White House. I stepped into the Oval Office.
We were scheduled to meet LBJ but he got called away at the last
minute.

I palled around with Amory Lovins in Baltimore, who is now some sort
of environmentalist guru.

Somebody made a CRT with an etched metal mask that was a ROM character
generator.

There was also a tube with an electrostatically deflected sheet beam
and two anodes, used as a balanced modulator.

And a dark trace CRT.

And radial deflection tubes used in radio altimeters.

And a companding 8-bit grey-code CRT ADC, used in the first PCM
telephone systems.

There were gas-filled CRTs where you could see the electron beam.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

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

 

[Joerg]

On 2019-05-24 07:04, John Larkin wrote:

On Fri, 24 May 2019 11:45:41 +0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in
news:QNOdnRgW4eK8onrBnZ2dnUU7-anNnZ2d@supernews.com:

On 5/23/19 11:09 AM, Joerg wrote:
On 2019-05-22 16:39, Chris Jones wrote:
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 :-(


Indeed :-(

Maybe the number of people who are able to operate such scopes
has dropped into the noise. Which would not surprise me.

It could be like it is with Hammond tonewheel organs where
production stopped in 1975. Their sound is unsurpassed but
luckily there are still tons around. Restoration becomes tougher
because they are old and most of the more sensitive innards are
mechanical parts. I needed a solid 20 hours to get one going
again. Now the prices for used ones start to rise. We just sold
ours because my wife could not play it anymore due to a wrist
injury. In contrast to old pianos it found a buyer almost
instantly. Just like it is with Tektronix 2465 scopes.


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


Well, you can get cheaper ones:

https://www.amazon.com/Sinometer-Single-Channel-Oscilloscope-
CQ501
0C/dp/B00NB58FJE/



I have three Tek analogue scopes: the 475A and 2467 work, and the
466 storage scope doesn't. Fifteen or so years ago, I used to use
a 2465A quite a lot, but these days I mostly use DSOs. (*)

I still really like the 246x's triggering.

Cheers

Phil Hobbs

(*) a couple of TDS 784As (1 GHz 4GS/s), a TDS 694C (3 GHz 10
Gs/s), and two 1180x sampling scope mainframes with about 20
plug-ins. Magic.


Tek makes extremely good gear!

Not always. I've had bugs in newer Tek scopes, and support has been
terrible. We buy Rigol now.

I love my Tek 7704A and the inserts for it but the TDS220 series was horrid.

When I bought a DSO about 10 years ago I chose GW-Instek because the
twice as expensive Tek had worse noise and way less sample memory which
made it useless for pulse-echo work.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Phil Allison]

On Saturday, May 25, 2019 at 8:33:40 AM UTC+10, pcdh...@gmail.com wrote:

The  ONLY sense in which Mr Hobbs is correct is the electrostatic focus of the >electron beam may not be perfect at the edges of the CRT face. A trivial concern.

Which is why Mr Allison probably thinks that SEMs use electrostatic focusing.

Cheers

Phil Hobbs

** What a fucking absurd reply !!

Hobbs does himself no credit posting garbage like this.



..... Phil

 

[Gerhard Hoffmann]

Am 24.05.19 um 23:55 schrieb John Larkin:

On Fri, 24 May 2019 13:14:58 -0700 (PDT),


And a companding 8-bit grey-code CRT ADC, used in the first PCM
telephone systems.

There were gas-filled CRTs where you could see the electron beam.

And a transient recorder by Tek based on a tube, 200 MHz IIRC.
Where usually is the phosphor, there were capacitors that
collected electrons from the beam and they could be read out.

They demo-ed us that thing, but we ended up with the newest
20 MSPS 8 bit flash ADC from TRW. A chip the size of a fingernail.

regards,
Gerhard

 

[John Larkin]

On Sat, 25 May 2019 01:23:20 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:

Am 24.05.19 um 23:55 schrieb John Larkin:
On Fri, 24 May 2019 13:14:58 -0700 (PDT),


And a companding 8-bit grey-code CRT ADC, used in the first PCM
telephone systems.

There were gas-filled CRTs where you could see the electron beam.


And a transient recorder by Tek based on a tube, 200 MHz IIRC.
Where usually is the phosphor, there were capacitors that
collected electrons from the beam and they could be read out.

They demo-ed us that thing, but we ended up with the newest
20 MSPS 8 bit flash ADC from TRW. A chip the size of a fingernail.

regards,
Gerhard

There were scan-conversion tubes, two CRTs face-to-face, one writing
and one raster scanning.

The Tek 7 GHz scan converter tube was French, and you can still buy
one.

https://greenfieldtechnology.com/products/digitizer.html


Nice company name and logo.





--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

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

 

[George Herold]

On Friday, May 24, 2019 at 6:43:55 PM UTC-4, Phil Allison wrote:

On Saturday, May 25, 2019 at 8:33:40 AM UTC+10, pcdh...@gmail.com wrote:
The  ONLY sense in which Mr Hobbs is correct is the electrostatic focus of the >electron beam may not be perfect at the edges of the CRT face. A trivial concern.

Which is why Mr Allison probably thinks that SEMs use electrostatic focusing.

Cheers

Phil Hobbs



** What a fucking absurd reply !!

Hobbs does himself no credit posting garbage like this.

Hmm, Phil A. I have no idea how old 'scopes moved the
electron beam around, compared to old TV crt's.
If it turns out Phil H. is right, and 'scopes used
E-fields, while TV's used E and B fields, will you agree?
(or is that not your point?)

B-fields are very important in electron optics.
For a few years I worked at an FEL, and got to steer
the e-beam around.
(the veterans/ old-timers there were much better than me. :^)

George H.

.... Phil

 

[Phil Allison]

George Herold wrote:

Phil Allison wrote:


The  ONLY sense in which Mr Hobbs is correct is the electrostatic focus of the >electron beam may not be perfect at the edges of the CRT face. A trivial concern.

Which is why Mr Allison probably thinks that SEMs use electrostatic focusing.

Cheers

Phil Hobbs



** What a fucking absurd reply !!

Hobbs does himself no credit posting garbage like this.



Hmm, Phil A. I have no idea how old 'scopes moved the
electron beam around, compared to old TV crt's.

** High time you found out then.

Arguing from a position of ignorance is classic, logical fallacy.

If it turns out Phil H. is right, and 'scopes used
E-fields, while TV's used E and B fields, will you agree?
(or is that not your point?)

** Try reading my original post - it is quite specific.

Hobbs ignored it and so have you.


FYI: CRTs in scopes and TV sets both use ES focussing.



...... Phil