https://www.edn.com/guard-circuit-provides-impedance-matching/
John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
https://www.edn.com/guard-circuit-provides-impedance-matching/
Driven shields have been around forever.
"john larkin" <jl@glen--canyon.com> wrote in message news:lfs8lkp9ot9ivtq47o8dmq9rgriemr08fp@4ax.com...
https://www.edn.com/guard-circuit-provides-impedance-matching/
Well it uses a 555.
The comments at the end suggest that there may be a few errors.
John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Driven shields have been around forever.
Since the mid 1930s, invented by Blumlein.
On 31/12/2025 8:31 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Driven shields have been around forever.
Since the mid 1930s, invented by Blumlein.
I worked at EMI Central Research for a couple of years (1976-1979), but
I'd heard of the Blumlein bridge even before that.
https://en.wikipedia.org/wiki/Alan_Blumlein
He died at age 38, and had his name on 128 patents. The IET has
published a biography, but it doesn't do him justice.
"The Life and Times of A.D. Blumlein" by Russel Burns ISBN 0 85296 773 X
and 978-0-85296-773-7
Bill Sloman <bill.sloman@ieee.org> wrote:
On 31/12/2025 8:31 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Driven shields have been around forever.
Since the mid 1930s, invented by Blumlein.
I worked at EMI Central Research for a couple of years (1976-1979), but
I'd heard of the Blumlein bridge even before that.
https://en.wikipedia.org/wiki/Alan_Blumlein
He died at age 38, and had his name on 128 patents. The IET has
published a biography, but it doesn't do him justice.
"The Life and Times of A.D. Blumlein" by Russel Burns ISBN 0 85296 773 X
and 978-0-85296-773-7
That is an excellent book - but be aware there is another book with a
very similar title which is a complete load of rubbish.
I was priviledged to have met Alan Blumlein's son, Simon, on several occasions and chatted to him about his father. Simon died about a year
ago; he was a lovely character with a similar sense of humour to his
dad.
On 1/01/2026 12:39 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 31/12/2025 8:31 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Driven shields have been around forever.
Since the mid 1930s, invented by Blumlein.
I worked at EMI Central Research for a couple of years (1976-1979), but
I'd heard of the Blumlein bridge even before that.
https://en.wikipedia.org/wiki/Alan_Blumlein
He died at age 38, and had his name on 128 patents. The IET has
published a biography, but it doesn't do him justice.
"The Life and Times of A.D. Blumlein" by Russel Burns ISBN 0 85296 773 X >> and 978-0-85296-773-7
That is an excellent book - but be aware there is another book with a
very similar title which is a complete load of rubbish.
I was priviledged to have met Alan Blumlein's son, Simon, on several occasions and chatted to him about his father. Simon died about a year ago; he was a lovely character with a similar sense of humour to his
dad.
I envy you the personal acquaintance.
I wasn't all that impressed by the
book. I don't think the author knew much about the electronics that
Blumlein worked on (few people do - he worked in a lot of different
areas) and it struck me as rather superficial in consequence.
Bill Sloman <bill.sloman@ieee.org> wrote:
On 1/01/2026 12:39 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 31/12/2025 8:31 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Driven shields have been around forever.
Since the mid 1930s, invented by Blumlein.
I worked at EMI Central Research for a couple of years (1976-1979), but >>>> I'd heard of the Blumlein bridge even before that.
https://en.wikipedia.org/wiki/Alan_Blumlein
He died at age 38, and had his name on 128 patents. The IET has
published a biography, but it doesn't do him justice.
"The Life and Times of A.D. Blumlein" by Russel Burns ISBN 0 85296 773 X >>>> and 978-0-85296-773-7
That is an excellent book - but be aware there is another book with a
very similar title which is a complete load of rubbish.
I was priviledged to have met Alan Blumlein's son, Simon, on several
occasions and chatted to him about his father. Simon died about a year
ago; he was a lovely character with a similar sense of humour to his
dad.
I envy you the personal acquaintance.
I was very lucky. Simon Blumlein was a patron of the City of London Phonograph and Gramophone Society and he attended their AGMs (and spoke
at some of them). I happened to see him killing time before the evening
meal and we fell into conversation. After that, we often had a quick
chat when time permitted.
I managed to record two of his talks, one on his researches into his
father's life and the other on his own life (he was deeply involved in optical design, loved a wide range of music and was also a ballet dancer
in his spare time!).
I wasn't all that impressed by the
book. I don't think the author knew much about the electronics that
Blumlein worked on (few people do - he worked in a lot of different
areas) and it struck me as rather superficial in consequence.
I thought the IET book wasn't too bad, are you sure that was the book
you read?
The other Book (whose name I have forgotten) was much much worse. The
author knew less than nothing about electronics or anything remotely scientific i.e. he thought he understood but obviously didn't have a
clue. For the benefit of less expert readers than himself, he provided explanations of the technical details in pseudo-scientific gobbledeygook using technical terms he had read in the source material but clearly
failed to understand.
It is one of the few books I have read where the author has added
negative value to his source material.
On 1/01/2026 4:35 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 1/01/2026 12:39 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 31/12/2025 8:31 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Driven shields have been around forever.
Since the mid 1930s, invented by Blumlein.
I worked at EMI Central Research for a couple of years (1976-1979), but >>>> I'd heard of the Blumlein bridge even before that.
https://en.wikipedia.org/wiki/Alan_Blumlein
He died at age 38, and had his name on 128 patents. The IET has
published a biography, but it doesn't do him justice.
"The Life and Times of A.D. Blumlein" by Russel Burns ISBN 0 85296 773 X >>>> and 978-0-85296-773-7
That is an excellent book - but be aware there is another book with a
very similar title which is a complete load of rubbish.
I was priviledged to have met Alan Blumlein's son, Simon, on several
occasions and chatted to him about his father. Simon died about a year >>> ago; he was a lovely character with a similar sense of humour to his
dad.
I envy you the personal acquaintance.
I was very lucky. Simon Blumlein was a patron of the City of London Phonograph and Gramophone Society and he attended their AGMs (and spoke
at some of them). I happened to see him killing time before the evening meal and we fell into conversation. After that, we often had a quick
chat when time permitted.
I managed to record two of his talks, one on his researches into his father's life and the other on his own life (he was deeply involved in optical design, loved a wide range of music and was also a ballet dancer
in his spare time!).
I wasn't all that impressed by the
book. I don't think the author knew much about the electronics that
Blumlein worked on (few people do - he worked in a lot of different
areas) and it struck me as rather superficial in consequence.
I thought the IET book wasn't too bad, are you sure that was the book
you read?
It's on my booKshelf and I posted both it's 10 and 13 digit ISBN numbers.
The other Book (whose name I have forgotten) was much much worse. The author knew less than nothing about electronics or anything remotely scientific i.e. he thought he understood but obviously didn't have a
clue. For the benefit of less expert readers than himself, he provided explanations of the technical details in pseudo-scientific gobbledeygook using technical terms he had read in the source material but clearly
failed to understand.
It is one of the few books I have read where the author has added
negative value to his source material.
The Russel Burns book wasn't that bad - it was just weak on the
technical content.
I've just re-read the last chapter, on the H2S radar whose flight trial killed Blumlein, and the technical analysis doesn't go deeper than distinguishing between klystons and magnetrons. It's remarkably superficial.
Bill Sloman <bill.sloman@ieee.org> wrote:
On 1/01/2026 4:35 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 1/01/2026 12:39 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 31/12/2025 8:31 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Driven shields have been around forever.
Since the mid 1930s, invented by Blumlein.
I worked at EMI Central Research for a couple of years (1976-1979), but >>>>>> I'd heard of the Blumlein bridge even before that.
https://en.wikipedia.org/wiki/Alan_Blumlein
He died at age 38, and had his name on 128 patents. The IET has
published a biography, but it doesn't do him justice.
"The Life and Times of A.D. Blumlein" by Russel Burns ISBN 0 85296 773 X >>>>>> and 978-0-85296-773-7
That is an excellent book - but be aware there is another book with a >>>>> very similar title which is a complete load of rubbish.
I was priviledged to have met Alan Blumlein's son, Simon, on several >>>>> occasions and chatted to him about his father. Simon died about a year >>>>> ago; he was a lovely character with a similar sense of humour to his >>>>> dad.
I envy you the personal acquaintance.
I was very lucky. Simon Blumlein was a patron of the City of London
Phonograph and Gramophone Society and he attended their AGMs (and spoke
at some of them). I happened to see him killing time before the evening >>> meal and we fell into conversation. After that, we often had a quick
chat when time permitted.
I managed to record two of his talks, one on his researches into his
father's life and the other on his own life (he was deeply involved in
optical design, loved a wide range of music and was also a ballet dancer >>> in his spare time!).
I wasn't all that impressed by the
book. I don't think the author knew much about the electronics that
Blumlein worked on (few people do - he worked in a lot of different
areas) and it struck me as rather superficial in consequence.
I thought the IET book wasn't too bad, are you sure that was the book
you read?
It's on my booKshelf and I posted both it's 10 and 13 digit ISBN numbers.
The other Book (whose name I have forgotten) was much much worse. The
author knew less than nothing about electronics or anything remotely
scientific i.e. he thought he understood but obviously didn't have a
clue. For the benefit of less expert readers than himself, he provided
explanations of the technical details in pseudo-scientific gobbledeygook >>> using technical terms he had read in the source material but clearly
failed to understand.
It is one of the few books I have read where the author has added
negative value to his source material.
The Russel Burns book wasn't that bad - it was just weak on the
technical content.
Yes, the technical content in Russel Burns' book wasn't too deep but it
was accurate and logical - unlike the other book which went into great
detail and got it wrong.
I've just re-read the last chapter, on the H2S radar whose flight trial
killed Blumlein, and the technical analysis doesn't go deeper than
distinguishing between klystons and magnetrons. It's remarkably superficial.
Similarly the section on Blumlein's improved recorder isn't very deep.
In fact almost any book which attempted to cover all of Blumlein's
inventions would have to draw a line somewhere, otherwise it would
become completely unwieldy.
I have read his notes (elsewhere) on the design of the cutterhead
equaliser, it took me several days to understand the way he was thinking about it. He eventually gave up the detailed analysis and basically
said "I'm not sure exactly why, but it just works".
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