00:00As the button was pressed, it released a hammer on a spring inside
00:03that snapped forward and struck a hidden rod, ringing it like a bell.
00:08Now this was too high for us to hear,
00:10but a microphone inside the TV picked up that tone
00:14and turned it into a command which changed the channel.
00:17And because your finger did the work, it didn't need batteries,
00:21and you never had to point it at the TV.
00:24Now each button struck a rod of a different length, making its own unique tone.
00:29So one turned the TV on, then another turned off the sound,
00:33All from a handful of metal bars.
