A SIMPLE HDD EXERCISER
by Evert Fruitman
My son, Tim, asked me, “Hey, Dad, can you make something like I saw at Comdex?" He had just come home from a computer-oriented seminar and wanted to find out if we could make the heads on a defective hard drive rattle back and forth for Show and Tell — silly question. His older sister, Joy, had asked about a louder metronome. His younger sister, Robbi, had asked about a violin-tuner. Joy now has a loud metronome and Robbi has a tuner (Nuts & Volts, November 1999). ..
A SIMPLE ONE-MHz FRQUENCY COUNTER
by Paul Florian
If you work with digital or analog oscillators, at some point you will want to double-check their operating frequency. Analog oscilloscopes will only get you within a half-order of magnitude or so; a good frequency counter will take you the rest of the way.
by Michael Chan
I am sure that everyone has the experience of being surprised by an unexpected message on occasion. It could be a declaration of love on a giant stadium screen, a greeting left behind by a plane, or a commercial sign beside the highway. Wouldn't it be nice to be able to deliver a personal message to impress your friends when they least expect it? Here is a simple gadget that enables you to wave your personal messages in glow-in-the-dark words, pictures, or both.