O'Reilly logo

Code: The Hidden Language of Computer Hardware and Software by Charles Petzold

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Chapter 14. Feedback and Flip-Flops

Everybody knows that electricity makes things move. A brief glance around the average home reveals electric motors in appliances as diverse as clocks, fans, food processors, and compact disc players. Electricity also makes the cones in loudspeakers vibrate, bringing forth sounds, speech, and music from the stereo system and the television set. But perhaps the simplest and most elegant way that electricity makes things move is illustrated by a class of devices that are quickly disappearing as electronic counterparts replace them. I refer to the marvelously retro electric buzzers and bells.

Consider a relay wired this way with a switch and battery:

If this looks a little odd to you, you're not imagining things. ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required