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Old 17th December 2012, 03:16 AM   #2391
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This has been a real Three Stooges weekend. On Saturday I took a couple 9V NI-MH batteries out of one of my test bench pre-amps and put them in my pocket and walked over to where I keep the charger. As these things go the batteries did a face to face meeting and by the time I got to my office I said, “what’s burning?” My first thought was that if the sprinklers get triggered everything is toast. Then I saw the smoke coming out of my pocket and pulled them out just before meltdown.
Then I wasted and embarrassing amount of time finding a jagged solder ball that was lodged under an electrolytic cap that had rubbed through the plastic coating shorting a node intermittently to V-.
All ended well I hope to have a summary up soon. A little taming of the BW and everything looks good. I’ll poke through the breadboard and and note exactly what is there (the differences are minor).
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Old 17th December 2012, 03:16 AM   #2392
RNMarsh is offline RNMarsh  United States
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JCX -- I can understand not having details of an IC or OPAmp. But a single transistor? We cant even get that right a lot of the time. Maybe we can learn to measure all the parameters important to audio ourselves and publish them. Thx-RNMarsh

Last edited by RNMarsh; 17th December 2012 at 03:20 AM.
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Old 17th December 2012, 03:33 AM   #2393
bcarso is offline bcarso  United States
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Originally Posted by dchisholm View Post
From the Analog Devices "Product Guide" for 1975. Note that the AD118 overall performance is approximately equivalent to a '741.
Dale
The slew rate was at least a factor of 12 more than the 741. I don't recall what the noise was like.
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Old 17th December 2012, 03:33 AM   #2394
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jcx - I can certainly get your problem to the top of the stack. The full encrypted models include all the details of the process characterization which is the real problem. Models based on more use of "real" transistors are a lot of work which needs experienced engineering input.
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Old 17th December 2012, 03:42 AM   #2395
bcarso is offline bcarso  United States
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Originally Posted by scott wurcer View Post
This has been a real Three Stooges weekend. On Saturday I took a couple 9V NI-MH batteries out of one of my test bench pre-amps and put them in my pocket and walked over to where I keep the charger. As these things go the batteries did a face to face meeting and by the time I got to my office I said, “what’s burning?” My first thought was that if the sprinklers get triggered everything is toast. Then I saw the smoke coming out of my pocket and pulled them out just before meltdown.
Then I wasted and embarrassing amount of time finding a jagged solder ball that was lodged under an electrolytic cap that had rubbed through the plastic coating shorting a node intermittently to V-.
All ended well I hope to have a summary up soon. A little taming of the BW and everything looks good. I’ll poke through the breadboard and and note exactly what is there (the differences are minor).
It's also been forensic electronics for me the last few days, working on manifold problems with a digital touchscreen watch not of my design. But after writing up a summary and transmitting it this morning, it was off to Disney Hall to hear Mozart, Hindemith, and Dvorak. Good music, great band as usual, wonderful hall, but frankly, a rather uninspired conducting job from Zubin Mehta.
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Old 17th December 2012, 04:15 AM   #2396
jcx is offline jcx  United States
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jcx - I can certainly get your problem to the top of the stack.
thanx, but not necessary - moslty a complaint - not a problem for me - I've already edited my copy to add the 46 dB missing DC gain, reduce the over spec Vos, I can put my own RL in series with the output to continue the datasheet plot's output Z rise beyond the gain intercept...
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Old 17th December 2012, 09:07 AM   #2397
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I've already edited my copy to add the 46 dB missing DC gain, reduce the over spec Vos, I can put my own RL in series with the output to continue the datasheet plot's output Z rise beyond the gain intercept...
Scott, is there even a simplified SPICE model for AD797?

Even if it doens't do 'accurate' Zo and stability with load
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Old 17th December 2012, 09:20 AM   #2398
fas42 is online now fas42  Australia
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Richard, after a quick look around there's this: ad1.lib. Can't vouch for anything within, but at least it's a starting point ...

Frank
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Old 17th December 2012, 10:08 AM   #2399
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Scott, is there even a simplified SPICE model for AD797?

Even if it doens't do 'accurate' Zo and stability with load
Gee Richard they are right there on the web site. This is the basis for them, http://www.analog.com/static/importe...tes/AN-138.pdf.

If you're very clever you can spot part of the problem in the credits. I don't think any other choices are much better.

jcx - The AD8067 post dates the initial onslaught of macro-modling, now, say no more.
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Old 17th December 2012, 04:53 PM   #2400
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In that 1990 article, it was acknowledged that sim work was beoming the way for engineers to evaluate and design circuits. So, by now the marketing dept must surely know that to sell more IC's (OPA, transistors et al) they need to supply accurate SPICE models. 'Cause it will sell parts faster/more. Though it is a chore to assign to some poor sole, its a win-win to do so. -RNM
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