John Curl's Blowtorch preamplifier part II

[Bonsai]

wow - great story Christophe

 

[fas42]

http://www.esperado.fr/images/stories/musiques/Kids_Final3.mp3:

Good one, Christophe ... I'm listening to it at the moment. The live stuff has a nice sense of space -- might send it through to the Foo Fighter's producer, could give him some ideas ... . Or maybe he would "protest" ...

Also, like the guitar sound on the studio take, something strange about the vocals though ...

Thanks for that,
Frank

 

[Esperado]

Good one, Christophe

Thanks a lot. Very nostalgic 'souvenirs'. ... We were so young.

 

[mikelm]

Question for John

Designing With Field-Effect Transistors. Second Edition

I can get this book quite cheaply in the UK

Will it be of any interest / use to someone like me how does not have high level maths ?

thanks

mike

 

[john curl]

I can't say, mike, without the authors name.

 

[mikelm]

Edited by Arthur D. Evans
Revised by Ed Oxner

 

[scott wurcer]

No, I did not say that. It is important you be clear on that.

The effect is slew rate dependent. The current density modification is directly proportional to the currents induced within the conductive material. The currents are directly proportional to the induced voltage ala Faraday's law of induction.

The resistance increase is a function of the absolute value of the rate of change of the current within the wire which is creating the magnetic field. That is why Ed sees the second harmonic.

jn

Had one of my favorite thought experiments this morning, consider a tri-wave constant alternating slew rate. Constriction is constant (?) therefore no modulation. I might be on the fence again.

 

[bcarso]

Question for John

Designing With Field-Effect Transistors. Second Edition

I can get this book quite cheaply in the UK

Will it be of any interest / use to someone like me how does not have high level maths ?

thanks

mike

IMO a good book. 1990, ISBN 0070575371. Wurcer pointed out that Ed Oxner's view of ion implantation as anathema for noise is a bit outdated, which has led me to be a bit more cautious about evaluating Ed's remarks here and there, but with that minor caveat I'd recommend the book. And in fact I don't even think the anti-implantation view is expressed within it

Brad

 

[scott wurcer]

IMO a good book. 1990, ISBN 0070575371. Wurcer pointed out that Ed Oxner's view of ion implantation as anathema for noise is a bit outdated, which has led me to be a bit more cautious about evaluating Ed's remarks here and there, but with that minor caveat I'd recommend the book. And in fact I don't even think the anti-implantation view is expressed within it

Brad

That's a minor point unless Ed also thinks nothing has changed in 33yr. It was a problem smart people worked on it a long time.

 

[mikelm]

But is this book suitable / useful for someone without high level maths ?

 

[bcarso]

But is this book suitable / useful for someone without high level maths ?

Yes. Although I'm not sure what you mean by high level. There are maths, but lots of applications-oriented content.

 

[bcarso]

That's a minor point unless Ed also thinks nothing has changed in 33yr. It was a problem smart people worked on it a long time.

I've forgotten where I saw his remarks about implantation, but it goes back. I think it was after that when Pease was excoriating, on his bully pulpit, one of his favorite people to hate, Keats Pullen, and RP alleged that JFETs didn't work as well as Pullen alleged they used to. Since I was still an employee at Harman this dates it to around 1993 or before.

 

[mikelm]

I was quite good at maths at school but did not pursue it beyond the age of 16 except AC theory etc which I studied at college I guess by high level I mean higher than that - beyond that it's difficult to explain what you know you don't know - as Donald Rumsfeld knows so well

 

[john curl]

Get the book, Mike. Ed Oxner is a friend of mine and is VERY skilled at Fets. He is the reference that both Charles Hansen and I go to when we have a special problem with fets.

 

[bcarso]

I was quite good at maths at school but did not pursue it beyond the age of 16 except AC theory etc which I studied at college I guess by high level I mean higher than that - beyond that it's difficult to explain what you know you don't know - as Donald Rumsfeld knows so well

I just flipped through it. Simple algebra, lots of graphics. Not a partial differential symbol to be seen, although it might have benefited from them

 

[mikelm]

thanks for that insight - I'll order a copy

 

[john curl]

It is interesting that Scott Wurcer is critical of Ed Oxner. Ed and I worked together, 40 years ago, when I had a QuanTech noise analyzer and I found low noise fets in Siliconix switching parts. Specifically, the J110 and the J113.
I designed both into the original Levinson JC-2. However, as years passed, Siliconix elected to change the process and it RUINED the J110, made it noisy, and it had to be replaced. Ed Oxner was rather upset about this at the time. It made the data sheets into a misleading lie.
In 1990, Toshiba also changed their process of making 2SK147 ultra low noise jfets, and I had to return hundreds of them to the distributor. Again, due to ion implantation.
Although I had a QuanTech available, at that time, I didn't bother testing every device anymore, because for more than 10 years, they were amazingly consistent. No more!
Perhaps they have fixed the problem, but it caught me twice.

 

[Mike Gergen]

I have that book and use it constantly. Worth having.

 

[bcarso]

It is interesting that Scott Wurcer is critical of Ed Oxner. Ed and I worked together, 40 years ago, when I had a QuanTech noise analyzer and I found low noise fets in Siliconix switching parts. Specifically, the J110 and the J113.
I designed both into the original Levinson JC-2. However, as years passed, Siliconix elected to change the process and it RUINED the J110, made it noisy, and it had to be replaced. Ed Oxner was rather upset about this at the time. It made the data sheets into a misleading lie.
In 1990, Toshiba also changed their process of making 2SK147 ultra low noise jfets, and I had to return hundreds of them to the distributor. Again, due to ion implantation.
Although I had a QuanTech available, at that time, I didn't bother testing every device anymore, because for more than 10 years, they were amazingly consistent. No more!
Perhaps they have fixed the problem, but it caught me twice.

Scott based a remark of his on what I had said about Ed decrying ion implantation, a long time ago. Oxner may no longer believe that it's an unrecoverably damaging process.

Note however the markings on this sample box of recent Toshiba duals, kindly provided to me by Dimitri

 

[john curl]

I just spoke to Ed Oxner, and he says that annealing MIGHT get the noise back down to low levels. He never tried it, himself. Siliconix did NOT follow up annealing as a solution to the problem. Maybe, other manufacturers did.