This book is exactly what it says, easy entertainment and science projects. I built some of these back in the 70's when the book was new. I'm sure that some of the components are harder to find now. This book is "not politically correct" anymore... it not only tells what TO do, but what NOT to do, and why you shouldn't do it... so it may make the projects somewhat less safe if the advice is not followed. Example, a radio transmitter that might exceed FCC regulations if the voltage and antenna length were exceeded... and that your signal could "be heard all over town". Isn't that what you'd want anyway ???