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  #21   Report Post  
Old June 15th 21, 04:00 PM posted to uk.d-i-y
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Default An electronic question.

On 15 Jun 2021 at 13:36:27 BST, "The Natural Philosopher"
wrote:

On 15/06/2021 10:35, Peter Able wrote:
Assuming that Fredxx has the right link, I think that you should take it
with a little pinch of salt.* An article originated 2000, referring to a
50+ year old Op Amp design (great advance though it was) is the first
hint.


More than a hint, since transistorss weren't invented then let alone opanps

Concerns about supply impedance at audio frequencies is another.


The paradox is explained when you note that the article is 20 years old and
the 741 50+ years old *now*.




If the guy was writing about designing with Dynamic Memory, then he'd be
closer to the mark.* A bit OTT for audio.

Incidentally, you attack power supply noise at the power supply.* I
wonder if the last components in your proposed PSU are - electrolytic
and / or other capacitors across the outputs.

But you attck nouse ON the power supply wherever its being generated

At least he isn't trying to argue that no semiconductor device will beat
a 12AX7 ;


In 1950, he would be correct



--
Roger Hayter



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Old June 15th 21, 04:04 PM posted to uk.d-i-y
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Default An electronic question.

On 15 Jun 2021 at 15:00:50 BST, "Roger Hayter" wrote:

On 15 Jun 2021 at 13:36:27 BST, "The Natural Philosopher"
wrote:

On 15/06/2021 10:35, Peter Able wrote:
Assuming that Fredxx has the right link, I think that you should take it
with a little pinch of salt.* An article originated 2000, referring to a
50+ year old Op Amp design (great advance though it was) is the first
hint.


More than a hint, since transistorss weren't invented then let alone opanps

Concerns about supply impedance at audio frequencies is another.


The paradox is explained when you note that the article is 20 years old and
the 741 50+ years old *now*.




If the guy was writing about designing with Dynamic Memory, then he'd be
closer to the mark.* A bit OTT for audio.

Incidentally, you attack power supply noise at the power supply.* I
wonder if the last components in your proposed PSU are - electrolytic
and / or other capacitors across the outputs.

But you attck nouse ON the power supply wherever its being generated

At least he isn't trying to argue that no semiconductor device will beat
a 12AX7 ;


In 1950, he would be correct


No, I don't know where that 20 years went either!

--
Roger Hayter


  #23   Report Post  
Old June 15th 21, 06:39 PM posted to uk.d-i-y
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Posts: 167
Default An electronic question.

On 15/06/2021 15:00, Roger Hayter wrote:
On 15 Jun 2021 at 13:36:27 BST, "The Natural Philosopher"
wrote:

On 15/06/2021 10:35, Peter Able wrote:
Assuming that Fredxx has the right link, I think that you should take it
with a little pinch of salt.* An article originated 2000, referring to a
50+ year old Op Amp design (great advance though it was) is the first
hint.


More than a hint, since transistorss weren't invented then let alone opanps

Concerns about supply impedance at audio frequencies is another.


The paradox is explained when you note that the article is 20 years old and
the 741 50+ years old *now*.

Which all but NatPhil seem to have understood. I'll try to write more
inclusively next time ;-}



If the guy was writing about designing with Dynamic Memory, then he'd be
closer to the mark.* A bit OTT for audio.

Incidentally, you attack power supply noise at the power supply.* I
wonder if the last components in your proposed PSU are - electrolytic
and / or other capacitors across the outputs.

But you attck nouse ON the power supply wherever its being generated

At least he isn't trying to argue that no semiconductor device will beat
a 12AX7 ;


In 1950, he would be correct




PA
  #24   Report Post  
Old June 15th 21, 06:52 PM posted to uk.d-i-y
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Default An electronic question.

On 15/06/2021 18:25, Fredxx wrote:

I'm struggling to see this phrase. A word search finds 3 'year's as part
of 2 'many years" and one "over the years". A search of '50' finds 4,
none of which pertain to time.

That is because it is not a quote. When I quote I follow the convention
of quotation marks - so I might have quoted such technical expressions
as "rubbish", "more rubbish", "unmitigated drivel", "frauds and charlatans".

And you?

PA


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Old June 15th 21, 06:59 PM posted to uk.d-i-y
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Default An electronic question.

On 15/06/2021 13:45, Dave Plowman (News) wrote:
In article ,
Peter Able wrote:
On 15/06/2021 00:17, Dave Plowman (News) wrote:
Shame you can't point us to the circuits. Even with your extra notes,
above, there are still many questions arising - not least if your notes
are incorrect. (It does happen!)

Most Op Amps applications are inherently PSU-ripple insensitive.

They are a design from Elliot Sound Products. But the published schematic
doesn't show the supply rail side of the design. You have to buy the PCB
to see it.


Assuming that Fredxx has the right link, I think that you should take it
with a little pinch of salt. An article originated 2000, referring to a
50+ year old Op Amp design (great advance though it was) is the first
hint. Concerns about supply impedance at audio frequencies is another.
If the guy was writing about designing with Dynamic Memory, then he'd be
closer to the mark. A bit OTT for audio.


I'd not read that article before.

Incidentally, you attack power supply noise at the power supply. I
wonder if the last components in your proposed PSU are - electrolytic
and / or other capacitors across the outputs.


The PS shown is fairly typical of a regulated analogue type designed for
use with audio circuits.


And it has some C at the LV output(s)?

PA

PS those of us in engineering at that time were so grateful to see the
741 kick the 709 out of designs.


  #26   Report Post  
Old June 15th 21, 07:01 PM posted to uk.d-i-y
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Default An electronic question.

On 15/06/2021 18:44, Fredxx wrote:
On 15/06/2021 18:25, Fredxx wrote:
On 15/06/2021 10:35, Peter Able wrote:
On 15/06/2021 00:17, Dave Plowman (News) wrote:
Shame you can't point us to the circuits.* Even with your extra notes,
above, there are still many questions arising - not least if your
notes
are incorrect. (It does happen!)

Most Op Amps applications are inherently PSU-ripple insensitive.

They are a design from Elliot Sound Products. But the published
schematic
doesn't show the supply rail side of the design. You have to buy the
PCB
to see it.


Assuming that Fredxx has the right link, I think that you should take
it with a little pinch of salt.* An article originated 2000,
referring to a 50+ year old Op Amp design (great advance though it
was) is the first hint.


I'm struggling to see this phrase. A word search finds 3 'year's as
part of 2 'many years" and one "over the years". A search of '50'
finds 4, none of which pertain to time.

FAOD the article was revamped in 2021. Perhaps they frequent this
newsgroup and updated it in the past day or so? Rod? No, he claims to
be a chemist.


Perhaps Rod Speed is AKA Rod Elliott?



Or Russ Andrews !

PA

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Old June 15th 21, 07:12 PM posted to uk.d-i-y
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Default An electronic question.

On 15/06/2021 18:37, Fredxx wrote:
On 15/06/2021 13:36, The Natural Philosopher wrote:
On 15/06/2021 10:35, Peter Able wrote:


At least he isn't trying to argue that no semiconductor device will
beat a 12AX7 ;


In 1950, he would be correct


I'm sure some transistors in Bell Labs in 1950 would have some
characteristic that would beat a 12AX7. Size might be one, though the
first ones had a hefty package.

Hell, the 12AX7 was only 'invented' in 1946.
* https://en.wikipedia.org/wiki/12AX7


Indeed Bell Labs would have. Vis-a-vis perceived lifetimes, the 2N3055
is on its state pension by now - but still a useful device to have in
the junk box. Go back the same number years from the 12AX7's birth date
and you are back in Victorian times!

PA
  #28   Report Post  
Old June 15th 21, 07:19 PM posted to uk.d-i-y
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Default An electronic question.

On 15/06/2021 19:02, charles wrote:
In article ,
Fredxx wrote:
On 15/06/2021 13:36, The Natural Philosopher wrote:
On 15/06/2021 10:35, Peter Able wrote:
Assuming that Fredxx has the right link, I think that you should take
it with a little pinch of salt. An article originated 2000, referring
to a 50+ year old Op Amp design (great advance though it was) is the
first hint.

More than a hint, since transistorss weren't invented then let alone
opanps



we certainly had transistors when I was at school - late 1950s and my copy
of "Mullard Manual of Transistor Circuits in dated 1961. That's 60 years
aago.


We're obviously of a similar age. When I won a book prize at grammar
school I nominated that as the prize. The school was scandalised! "No
one has EVER been given a paperback book at Speech Day!!!!". The
compromise was that I choose a conventional book (a hardback Latin
dictionary), as well.

I still have both. You can guess which is the more thumbed !

PA

  #29   Report Post  
Old June 15th 21, 07:25 PM posted to uk.d-i-y
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First recorded activity by DIYBanter: Dec 2020
Posts: 1,591
Default An electronic question.

On 15/06/2021 10:35, Peter Able wrote:
On 15/06/2021 00:17, Dave Plowman (News) wrote:
Shame you can't point us to the circuits.* Even with your extra notes,
above, there are still many questions arising - not least if your notes
are incorrect. (It does happen!)


Most Op Amps applications are inherently PSU-ripple insensitive.


They are a design from Elliot Sound Products. But the published schematic
doesn't show the supply rail side of the design. You have to buy the PCB
to see it.


Assuming that Fredxx has the right link, I think that you should take it
with a little pinch of salt.* An article originated 2000, referring to a
50+ year old Op Amp design (great advance though it was) is the first
hint.


I'm struggling to see this phrase. A word search finds 3 'year's as part
of 2 'many years" and one "over the years". A search of '50' finds 4,
none of which pertain to time.

FAOD the article was revamped in 2021. Perhaps they frequent this
newsgroup and updated it in the past day or so? Rod? No, he claims to be
a chemist.

Concerns about supply impedance at audio frequencies is another.


Many op-amps are effective Class B outputs, where pulses in current
occur when the output is changing.

If the guy was writing about designing with Dynamic Memory, then he'd be
closer to the mark.


DRAM is relatively simple to decouple. There are models that predict
voltage dips and resonant behaviour for multiple decoupling capacitors
on power pins with multiple value.

A bit OTT for audio.


The design voltage ripply for DRAMS would be somewhat higher than levels
preferred for audio.

Incidentally, you attack power supply noise at the power supply.* I
wonder if the last components in your proposed PSU are - electrolytic
and / or other capacitors across the outputs.


What outputs? I would hope regulator outputs. It's normal to use a mix
of types, though high value ceramic is sometimes used alone.

At least he isn't trying to argue that no semiconductor device will beat
a 12AX7 ;-}


That would be difficult to argue. I note on some equipment the valve is
there for pure show, and while the heater is glowing all they are
producing is heat.
  #30   Report Post  
Old June 15th 21, 07:37 PM posted to uk.d-i-y
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Default An electronic question.

On 15/06/2021 13:36, The Natural Philosopher wrote:
On 15/06/2021 10:35, Peter Able wrote:
Assuming that Fredxx has the right link, I think that you should take
it with a little pinch of salt.* An article originated 2000, referring
to a 50+ year old Op Amp design (great advance though it was) is the
first hint.


More than a hint, since transistorss weren't invented then let alone opanps


From what I can read I can't see any reference to 50+ years and the
article was revamped in 2021.

BTW, the Transistor was invented in 1947.
https://en.wikipedia.org/wiki/History_of_the_transistor

It's perhaps ironic they were trying to fabricate a J-FET and that
Julius Lilienfeld is credited with the first patent on the FET in 1925.
https://en.wikipedia.org/wiki/Julius_Edgar_Lilienfeld

Concerns about supply impedance at audio frequencies is another.
If the guy was writing about designing with Dynamic Memory, then he'd
be closer to the mark.* A bit OTT for audio.

Incidentally, you attack power supply noise at the power supply.* I
wonder if the last components in your proposed PSU are - electrolytic
and / or other capacitors across the outputs.

But you attck nouse ON the power supply wherever its being generated

At least he isn't trying to argue that no semiconductor device will
beat a 12AX7 ;


In 1950, he would be correct


I'm sure some transistors in Bell Labs in 1950 would have some
characteristic that would beat a 12AX7. Size might be one, though the
first ones had a hefty package.

Hell, the 12AX7 was only 'invented' in 1946.
https://en.wikipedia.org/wiki/12AX7



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