John Curl's Blowtorch preamplifier part II - Page 1813

john curl · 19th November 2011, 09:23 PM

PMA, increase the rep-rate by two or more. Make it 500ns, or even less. Magnify the vertical. I am only remembering this from the article done by TEK about 35 years ago.

scott wurcer · 19th November 2011, 10:26 PM

Quote:

Originally Posted by PMA

I am not sure if I understand the word 'hook' regarding the plot.

PMA - I've completely lost the drift here, are you saying this has nothing to do with DA, series inductance, or what?

john curl · 19th November 2011, 10:33 PM

Perhaps I went in the wrong direction. PMA, please slow the rep speed and 'contain' the overshoot so that it sort of looks like a 'hook'.

john curl · 20th November 2011, 03:46 AM

Let me try to explain what is being discussed here. About 35 years ago, a Tektronix engineer or two wrote an article on 'CIRCUIT HOOK' (as far as I can distinctly remember) which is a rather strange characterization of a circuit 'glitch'. They were designing attenuators, and they found a problem. Guess what? It was the SAME problem that PMA has just found and fixed! It was due to DA in the system, in the circuit board in Tek's case, and in the poly cap, in YBA's case.
Now why did they call it HOOK?
If YBA can remeasure the problem and EXAGGERATE the problem, so that the DIFFERENCE between ideal and the problem is easy to see, then you can sort of see a HOOK in the ERROR difference. I hope that this helps. I am not trying to talk in code, or anything, but to point out that YBA is not alone with his discovery, and it should be noted by virtually anyone making attenuators, if they really care about optimum performance.

PMA · 20th November 2011, 05:33 AM

Quote:

Originally Posted by john curl

Perhaps I went in the wrong direction. PMA, please slow the rep speed and 'contain' the overshoot so that it sort of looks like a 'hook'.

The measurements I am showing are 1 year old. I can add a couple of measurements in a different time axis resolution, but with same circuit, signal and phenomenon. I hope it helps, at least a little.

john curl · 20th November 2011, 05:39 AM

PMA, it doesn't look that you have enough resolution to show it properly.

PMA · 06:28 AM

The plots are 1 year old and I have no other plots with me.

We have the data with enough resolution (12-bit A/D) captured at the site, but I have no access to them at the moment.

But IMO you can easily see it even in these low resolution plots.

john curl · 20th November 2011, 06:42 AM

Yes, it is enough to demonstrate the problem.

EUVL · 20th November 2011, 07:19 AM

> .... an article from either the IRT (IRT :: Home) or the VDT (http://www.tonmeister.de) Journal quite a few years back ....
> ... the VDT and IRT sites are goldmines of information, ....

Thorsten,

Where can I find their publications or articles ?
Could you kindly post a link ?

Thanks,
Patrick

ThorstenL · 20th November 2011, 07:45 AM

Hi,

Quote:

Originally Posted by EUVL

Where can I find their publications or articles ?
Could you kindly post a link ?

I have not found an obvious index, such as for the old technical bulletins of the Beep on their site (Beep = UK Slang for BBC). So for my article I have to get to the paper, for anything else, just snoop around. There is plenty of acoustical stuff...

Ciao T

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19th November 2011, 09:23 PM	#18121
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	PMA, increase the rep-rate by two or more. Make it 500ns, or even less. Magnify the vertical. I am only remembering this from the article done by TEK about 35 years ago.

19th November 2011, 10:33 PM	#18123
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Perhaps I went in the wrong direction. PMA, please slow the rep speed and 'contain' the overshoot so that it sort of looks like a 'hook'.

20th November 2011, 03:46 AM	#18124
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Let me try to explain what is being discussed here. About 35 years ago, a Tektronix engineer or two wrote an article on 'CIRCUIT HOOK' (as far as I can distinctly remember) which is a rather strange characterization of a circuit 'glitch'. They were designing attenuators, and they found a problem. Guess what? It was the SAME problem that PMA has just found and fixed! It was due to DA in the system, in the circuit board in Tek's case, and in the poly cap, in YBA's case. Now why did they call it HOOK? If YBA can remeasure the problem and EXAGGERATE the problem, so that the DIFFERENCE between ideal and the problem is easy to see, then you can sort of see a HOOK in the ERROR difference. I hope that this helps. I am not trying to talk in code, or anything, but to point out that YBA is not alone with his discovery, and it should be noted by virtually anyone making attenuators, if they really care about optimum performance.

20th November 2011, 05:39 AM	#18126
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	PMA, it doesn't look that you have enough resolution to show it properly.

20th November 2011, 06:42 AM	#18128
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Yes, it is enough to demonstrate the problem.

20th November 2011, 07:19 AM	#18129
EUVL diyAudio Member Join Date: Oct 2003	> .... an article from either the IRT (IRT :: Home) or the VDT (http://www.tonmeister.de) Journal quite a few years back .... > ... the VDT and IRT sites are goldmines of information, .... Thorsten, Where can I find their publications or articles ? Could you kindly post a link ? Thanks, Patrick