Jim Williams designs a new Super Oscillator

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#4
I have used some AP kit and its awsome, too expensive to have at home though and a PC sound card can do the same mesurments with less conveniance as the cheaper units. The artical claims the oscilator in the AP hardware is lower noise still and adjustable?!?!
 
#6
Bob's comment is like mine, I squeezed -150dB out of my old Sound Technology 1700B in 1992 with a few tricks (good enough for me). I talked with Jim about "distortionless" oscillators with distortion trims last time I saw him. If you can get a copy of his AES talk and especially his references you can get the whole story. It turns out, in my case, the way a Wein bridge "really" works was buried in an obscure text book I had at MIT. Jim's reference from HP labs covering the same issue is in his words, "The best piece of engineering he has ever seen".
 
#7
Jim sent me a copy of the article. It was Bernie Oliver's cover article in the Apr.-June 1960 issue of the HP Technical Journal. The gist is you can't simply make a distortionless Wein bridge oscillator. Bernie argued one way and my text used it to explain the usefulness of Volterra math (comming essentially to the same answer). I can't wait to see the latest incarnation, I'm sure Jim has a few secret rooms with virtually unavailable exotic components.
 
#12
scott wurcer said:
Bob's comment is like mine, I squeezed -150dB out of my old Sound Technology 1700B in 1992 with a few tricks (good enough for me). I talked with Jim about "distortionless" oscillators with distortion trims last time I saw him. If you can get a copy of his AES talk and especially his references you can get the whole story. It turns out, in my case, the way a Wein bridge "really" works was buried in an obscure text book I had at MIT. Jim's reference from HP labs covering the same issue is in his words, "The best piece of engineering he has ever seen".
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Is that "Modern Perspectives on Hewlett's Sinewave Oscillator" from the 125th convention?
 
#17
carpin, I'm not quite sure why you're quoting me and the linking to this thread. Yes, I can read, and yes, I have read the whole thread from the start.

I was commenting on post no.8, by klewis:-
Not being able to aford an AP just yet, can anyone point me to an article, book or reference on how to use a scope in crossplot mode to measure distortion?
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If you look at the OP's EDN link and scroll down a bit, you will see the following comment by Bob Pease:-

Bob Pease commented:
I have been measuring op-amps with -159 dB of distortion, using an old Tek 2445 ANALOG Scope in Crossplot mode. I do this on the bench in my office because I don't have any A.P. equipment. I'm pushing past -164 dB next. / rap
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I was merely pointing out what I thought the source of Bob Pease's comment may be, to try and assist klewis.
 
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