Instead he suggests that it would be easier to make a radio ... am going to build this soon. But be careful. It's fine for a time traveler stuck in the past to build and use a spark gap ...

And building this one-transistor transmitter is just about the simplest way to dive into the world of DIY radio. Of course ... for amplitude modulation (AM) voice work. The circuit is flexible ...

and in the DIY world, usually as a way for robots to detect obstacles. But for a weekend project, [Vinod.S] took the ultrasonic transmitter and receiver from a distance-meter module and used ...