Wow, what a cool piece of engineering. So simple, so effective, no batteries.

The Space Command is a product of mechanical engineering rather than electrical. By pressing a button on the remote, you set off a spring-loaded hammer that strikes a solid aluminum rod in the device, which then rings out at an ultrasonic frequency. Each button has a different length rod, thus a different high-frequency tone, which triggers a circuit connected to a microphone in the television to finish the command.

The buttons on Zenith’s original ‘clicker’ remote were a mechanical marvel