This book is dedicated to the memory of my father, Charles Wallace Gay, who passed away this year. He didn’t remember it when we discussed it last, but he was responsible for sparking my interest in electronics at an early age. He had brought home from his used-car business two D cells, a piece of blue automotive wire, and a flashlight bulb. After showing me how to hold them together to complete the circuit and light the bulb, I was hooked for life.

I am also indebted to my family for their patience. Particularly my wife ­Jacqueline, who tries to understand why I need to do the things I do with wires, solder, and parts arriving in the mail. I am glad for even grudging acceptance because I’m not sure that I could give up the thrill of moving electrons in some new way. ­Sometimes hobby electronics projects have no real justification beyond “because we can!”