Last week, I was able to spend a few hours at the Computer History Museum. Of course, Jim's lab bench from Linear Tech is still on display, but the main purpose of my visit was to explore the exhibits (which were closed when I attended the unveiling of Jim's bench). I will have several upcoming blog posts (about oscilloscopes!) when I finish sorting through my photographs, but I thought I'd start with a quick post today.
In App Note 55, Jim showed the collection of equipment that he titled "Typical Efficiency Measurement Instrumentation", including RMS voltmeters, a clip-on ammeter, and a input DVM. He also included a "hand calculator" (lower right) for computing the circuit efficiency.
The "calculator" that he included is a rare and beautiful artifact, the hand-cranked Curta calculator, with an amazingly intricate mechanism. The Computer History Museum has several on display.
The Museum also has a webpage with some more photos of the calculator.