Dear Dennis... EN-Genius Network's Dennis Feucht answers your design queries in his new Circuit Design Clinic! June, 2012

EN-Genius Network presents a new, interactive analog design service to readers! Send us your design questions (with relevant data; schematics in JPEG or GIF, please) for some free engineering advice from EN-Genius Network's circuit consultant, Dennis Feucht, on how you might solve a design problem or improve circuit performance. Submissions may be edited for clarity or brevity, and submitters and their email addresses will remain anonymous (unless otherwise indicated). Please send your questions to Dennis here.

Low-Cost Perspicuous Displays: Part 1

by Dennis L Feucht

With the challenge of finding a way for youth and others beginning in electronics to build an oscilloscope, some musing brought forth several alternatives to electrostatically-deflected cathode-ray tubes (CRTs). Their expense and high-voltage circuitry leave them as less than optimal for beginners (as do magnetically-deflected CRTs from old TVs), though a glass tube displays internal components and offers wonderful functional perspicuity to the observer of moderate perspicacity. Deflection plates, screen, grids, and cathode can all be observed directly and their operation easily envisioned. The CRT is functionally perspicuous.

One of the objectives for beginners (and maybe for the rest of us too!) is to use technology that can be understood down to an elemental level. There are, of course, limits of decomposition, yet in our era, a disturbing trend in technology is its increasing functional opacity. Computers are a prime example in that few know what goes on ‘under the hood’ yet many are dependent on computers for accomplishing their various tasks. Computer software is even more troublesome in this regard. A display for beginners should not only be modest in cost but should also have ‘a hood that opens’ so that both its structure and behavior can be viewed down to a suitably elemental level.

...download complete article here (750 KB PDF)