Demonstration apparatus to illustrate the operation of synchronous machines
An undergraduate electrical engineering thesis by Klaus Edward Hellstrom, submitted at the University of Illinois in 1908, on a demonstration apparatus for teaching the operation of synchronous machines. The plates are hand-drawn in ink on tinted paper: vector and phasor diagrams built from concentric circles, radiating lines and lettered angles in black, red and blue, plus sectioned mechanical views of a bearing and base, useful for layered line work, hand-lettered figure captions and two-colour geometric overlays.
