31 December 2013

Just 10

I am embarrassed to realize that this post is only my tenth post for 2013. Thus, a "look back" can be comprehensive AND short.  Out of those ten posts, only five contained actual content, and all five were "Scope Sundays":
Other than that, I posted a "Top Five" list for 2012, a link to my EE Proto blog (which also suffered a dearth of posts), an advert for my "History of Bandgap References" talk, a picture of Jim, and this post.

I promise 2014 will be better... I already have a number of posts planned. (Plus, I still have 10 of Jim's app notes to read!)

20 November 2013

Scope Sunday 46

Our correspondent writes with the following question: Do you recognize this scope?

This photo appears on page 240 of the 1963 MIT yearbook, and appears to be a picture of an undergraduate teaching laboratory. Notable is the method of showing the time and voltage settings. There was a hole in the front panel above the knob and the sensitivity was shown through a back-lit dial. The scope was tan in color with dark brown features.

Several people have suggested that the brand name was "Analogic", but the present-day Analogic Corporation did not exist until 1967.

Does anybody recognize this scope?

Footnote: Our initial correspondent is none other than John Addis, who wrote Chapter 14, "Good Engineering and Fast Vertical Amplifiers", in Jim Williams's first book. Bernard Gordon, founder of Analogic Corporation, wrote Chapter 5 in that same book. It's all connected.

23 June 2013

Scope Sunday 45

My friend Eugene pointed me to a Tektronix 661 on eBay (it was the first one I'd seen in quite a while). I've wanted this scope for a long time. I even mentioned back in Scope Sunday 2.

Jim mentioned his Tek 661 quite a few times: He used it in App Note 74, and tt is pictured on the back cover. He used it in Figure 77 of App Note 72 and also in App Note 61. I'm excited to have my own, and if it works, I'll have to get to work on building some more high-speed pulse generators.

17 June 2013

Scope Sunday 44

I'm a day late with this post, but I did want to report on recent activities. Yesterday, I spent the morning at the MIT Swapfest, but did not purchase anything. Instead, I sold some Hewlett Packard and General Radio manuals and catalogs that I had rescued from the trash at M.I.T. (Next month, I will be selling some similarly diverted Tektronix manuals.) There was a $10 Tektronix 564B, but I'm not really into the 560 series (despite the fact that I own a 3S1 and one 561B). Besides, someone else had bought it before the end of the flea market.

I did buy a scope last week (actually, two, but the second half of this story will come next week): I found a Tektronix 514AD on Craigslist.

This scope has some interesting features: It was the first scope to offer both a 10-MHz bandwidth and DC response (the 511 only had the former, the 512 only had the latter). The 514AD version include a 24-section 250-ns LC delay line. It also includes (I am told) tons of selenium rectifiers. Fun!

12 June 2013

14 April 1948 -- 12 June 2011

We miss you, Jim.

Observe a moment of silence today while the tubes in your scope warm up.

03 June 2013

Some History of Bandgap References

I am giving a talk at Stanford University on Thursday. It's not about Jim Williams, but it does mention Bob Widlar (and it includes my favorite Bob Widlar story [spoiler!]). If you're in the neighborhood, please come!

Some History of Bandgap References
Rethinking Analog Design Seminar
Stanford University Electrical Engineering
4pm, Thursday, 6 June 2013
Allen 101


Prankster Bob Widlar designed the first commercial bandgap voltage reference and introduced it with an elaborate ruse in 1969. The National Semiconductor LM109 was more than a simple reference, it was a feature-packed integrated circuit that jump-started the category of three-terminal voltage regulators. Over the next few years, the LM109 was followed up by the National LM113 current shunt, the LM199 temperature-controlled buried zener, and ground-breaking products from Analog Devices, Precision Monolithics, Linear Technology, and others. This talk discusses the history and design of voltage regulators, references, and current sources from the 1960s to present day.

12 May 2013

Scope Sunday 43

Once again, I find myself apologizing for a lengthy absence, but this term's teaching obligations got the better of me. I taught three classes this Spring, and that's a schedule that I should remember NOT to repeat. However, I have submitted final grades for two of the classes, and I'm looking forward to getting back to my "other" jobs. In the meantime, here are three scope-related updates:

1. Last weekend, I attended NEAR-fest up in Deerfield, N.H. This year, the weather was beautiful, but the pickings were slim. I did, however, buy two scope plug-ins, 1A7A and a 7M13.

Both of these plug-ins remind me of Jim. Jim suggested that the 1A7 manual was one of the first examples of the word "cascode" being used to refer to the transistor circuit (I subsequently found an earlier reference). And, of course, the 7M13 is the plug-in that he used to put his "signature" on the cartoon in App Note 94. The cartoon shows off his 7104 scope, "I'm going as fast as I can."

2. On the way home from NEAR-fest, I stopped by Electronic Surplus Services in Manchester, but I all found was a shelf of undesirable plug-ins (mostly 7A18 vertical amplifiers and slow time bases).

Compare the photo above to the photo below that I took ONE YEAR AGO. Other than better picture quality, not much has changed. I guess there isn't much market for $20 7A18 plug-ins and 7B53 plug-ins.

3. Next weekend is the Dayton Hamvention. Let me know if you're going; I hope to see you there. Here's a picture I took last year:

23 January 2013

EE Prototyping Redirect

I have previously posted here about the EE Prototyping course that I will be teaching at Olin College this spring (see all posts with the label "Prototyping"). While I still believe that Jim Williams would have loved this class, I have decided to split that discussion off into its own dedicated blog.

If you'd like to continue to follow the development of "EE Proto" this term, please join my students and me over at eepro.to.

22 January 2013

Scope Sunday 42

A friend emailed me last week, and said that he had some Tektronix 500-series plug-ins for me.  I told him that I was happy to give them a good home.  When I arrived at his house on Sunday, he had a dozen-and-a-half plug-ins for me, and also this back-breaking beast:

He said that it has a small oscillation problem, and it didn't come with any fixtures, but I am very pleased.  I have several 575s (and even a 175 with the special cable), but this treasure is my first 576.

01 January 2013

Top Five Posts 2012

I started this blog in July 2011, so today is the first time I have a year of data for an end-of-year round up. A year ago, I declared the "Top Five Most Popular Posts in 2011" with an incomplete year of data. Therefore, today, with a full year of data, I do declare:

The Top Six Most Popular Posts in 2012
  1. Best App Notes Page
  2. Not really a "post" in the strictest sense of the word, but this page received the most traffic in 2012. It continues to be updated as I continue to read...
  3. Scope Sunday 13 (2011 rank: #3)
  4. Photos from my trip to the Computer History Museum to see the opening night of Jim's Linear Technology laboratory bench on display (with my business card in the mess).
  5. Vintage Scopes are Better, part 1
  6. The first part of my five-part series on why vintage analog oscilloscopes are better than modern digital ones, with plenty of quotes from Jim. See also part two, part three, part four, and part five.
  7. Scope Sunday 23
  8. Notes and photos from my return trip to the Computer History Museum, where I make note of the large number of Tektronix oscilloscopes in their collection (whether they want to admit it or not!).
  9. Scope Sunday 3 (2011 rank: #1)
  10. My airline adventure with a Tektronix 453, along with a letter from Jim.
  11. My Favorite Widlar Story
  12. A retelling of the three-terminal-voltage-regulator prank. My second-favorite Bob Widlar story is the one about the sheep.

Note that some of these posts are from 2011, but the ranking is based only on their traffic in 2012 (search engines at work). Of course, once again I note that listing these links gives these posts a head start in the race for "Most Popular Posts in 2013" (it's an interesting positive-feedback loop, isn't it?), but I hope that I will produce even more interesting posts in the coming months!

Which post was your favorite?