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.