Scope Sunday 25

When I visited the Computer History Museum three weeks ago, I also stopped at two electronic surplus shops, WeirdStuff and HSC (I also visited these stores back in October). Unfortunately, the pickings were slim.

At WeirdStuff, there was a Tektronix 502 oscilloscope. Unfortunately, it was priced at $160.

The Tektronix 7904 that I saw last time was still on the back wall, now with a sticker that says "no power", but still with a price tag of $250. (This scope has been there for at least six months.)

I think both of these scopes are priced five times too high. Fifty dollars is a fair price for a broken 7904.

I saw similar overpricing at HSC. They seem to have a lot of untested gear in the $45 to $75 range. I buy a lot of electronic surplus junk, but my what-the-hell price (as in, "what the hell, I'll just buy it and see") for a random untested, unidentified box is a lot less than $45.

However, I have bought things at HSC in the past, and I will buy things at HSC in the future. For one thing, I appreciate and support any business that does this:

This picture shows part of the databook library at HSC. This collection of databooks puts the collection of databooks in the M.I.T. Library to shame. I have referenced these books in the past, and I hope to be able to reference them in the future. Not everything is available on the web (as my commentary in the "Bibliography of Jim Williams" attests). Having real, printed databooks and handbooks available for perusal is a valuable resource and a public service. Thank you, HSC.

Halfway there!

With Wednesday's post about App Note 49, I have now covered 31 of Jim's 62 app notes (but only 40% by page count). I thought that it would be a good time to take a quick look back.

Top five app notes (so far):

1. App Note 47, High speed amplifier techniques: A designer's companion for wideband circuitry (the crown jewel, of course: absolutely required reading).
   
2. App Note 25, Switching regulators for poets: A gentle guide for the trepidatious (the advice, the cartoon, and the lack of equations).
   
3. App Note 43, Bridge circuits: Marrying gain and balance (mostly for the low-distortion sine-wave oscillator development).
   
4. App Note 28, Thermocouple measurement (the history lessons and discussions of errors).
   
5. App Note 45, Measurement and control circuit collection: Diapers
   and designs on the night shift (for the baby-bottle rating system and Figure 36).
   

Two other app notes that would have been contenders are App Note 10 and App Note 13, but the good parts of those notes were updated and incorporated into App Note 47. App Note 49 would also get an honorable mention, but it's quickly going to be buried by its successors, App Notes 55 and 65.

Top five best circuits (so far):

1. App Note 43 Figure 48 (Sine wave oscillator with 3ppm distortion)
   
2. App Note 14 Figure 1 (King-Kong V-to-F)
   
3. App Note 23 Figure 16 (The Zoo Circuit V-to-F)
   
4. App Note 21 Figure 12 (Son of Godzilla Amplifier)
   
5. App Note 47 Figure 116 (Complete AM Radio Station)
   

Top five best quotes (so far):

1. "Mother Nature loves throwing a surprise party. Technologically driven arrogance is a dangerous brew, as any Titanic passenger will assure you." (p.103 in Chapter 13, "Should Ohm's Law be repealed" in Jim's first book)
   
2. "The author acknowledges Carl Nelson's abundance of commentary, some of which was useful, during preparation of this work" (p.13, App Note 25)
   
3. "While I certainly wouldn't wish lifetime employment on a digital circuit board to anyone, the reality is that the need exists. (Footnote: I suppose it's not all that bad. Some of my best friends are digital circuits. If I had a daughter, I'd even consider letting her go out with one.)" (p.1, App Note 31)
   
4. "History records that Hewlett and his friend David Packard made a number of these type oscillators. Then they built some other kinds of instruments." (p.29, App Note 43)
   
5. "The translation of this statement is to hide the probe when you are not using it. If anyone wants to borrow it, look straight at them, shrug your shoulders and say you don't know where it is. This is decidedly dishonest, but eminently practical. Those finding this morally questionable may wish to re-examine their attitude after producing a day's worth of worthless data with a probe that was unknowingly readjusted." (p.12, App Note 49)
   

Also, I've updated the bibliography again. Onward!

The New Book

On Thursday, I finally received a copy of the new book, "Analog Circuit Design, A Tutorial Guide to Applications and Solutions". Edited by Bob Dobkin and Jim Williams together, it is a collection of 41 Linear Technology Application Notes reprints, 27 of which were written by Jim.

Dobkin's dedication in the book is especially touching: "In memory of Jim Williams, a poet who wrote in electronics."

Unfortunately, it is just a collection of Linear Tech App Notes. While I admit that it is nice to have hardbound copies of some of these app notes (like App Note 47), I am disappointed that there is no new material here.

I have updated the bibliography to include information about this book.

A Bibliography of Jim Williams

After digging up Jim's application notes from National Semiconductor last week, I started thinking that it would be useful to have a complete compiled bibliography of all of Jim's publications. So I spent a little bit of time (OK, a lot of time) searching around, and I've put together a draft of "A Bibliography of Jim Williams". In 2009, Jim told me that he had over 350 publications. I've found 288 so far. Please notify me of any omissions.

The bibliography can be found at http://web.mit.edu/klund/www/jw/jwbib.pdf.

Back to our regularly scheduled Linear Tech app notes tomorrow.

National App Notes

Last Thursday, I mentioned the National Semiconductor Application Note 294 that Jim wrote. On Friday, a commenter referred to a circuit in NSC App Note 299 (which Jim also wrote).  Jim worked for National in the Linear Integrated Circuits Group from 1979 to 1982. During this period, he wrote many app notes, but getting a complete list of his notes is a bit of a mystery hunt. There are several unfortunate reasons for this difficulty:

1. National doesn't always print bylines with author's names on their app notes.
2. National regularly deletes old app notes from their archives.
3. National sometimes updates the publication date of their app notes upon revision.

However, I spent some time digging, and I think I now have a complete list. To find which application notes he wrote, I had to infer Jim's authorship based on the right time period and other clues. One reliable clue was the inclusion of photographs of Jim's Tektronix 556 oscilloscope with the damaged graticule. In other cases, I made educated guesses based on his use of references, footnotes, or subject matter. A reference to one of Jim's past publications is a good hint, a footnote discussing the Hewlett Packard HP200 oscillator is a dead giveaway!

Based on this research, there are (at least?) twenty-one application notes that he wrote.  They are App Notes 256, 260, 262, 263, 264, 265, 266, 269, 272, 285, 286, 288, 289, 292, 293, 294, 295, 298, 299, 301, and 311. Not bad for three years' work!

You can find most of the app notes on National's master list.  For more details on the frustrations of this mystery hunt, see http://web.mit.edu/klund/www/jw/jw-nsc.html.  (After I finish reading all of the Linear Tech app notes, it will be interesting to go back and reread all of his National app notes.  I should have done that first.)