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Interestingly, some early wireless TV remotes used sound this way. The battery-free remotes would strike a tone when a button was pressed, and carefully tuned f
by slowmover 13y ago
Interestingly, some early wireless TV remotes used sound this way. The battery-free remotes would strike a tone when a button was pressed, and carefully tuned forks in the TV set would resonate in response, triggering the remote function.
http://www.tvhistory.tv/1957_Zentih_Ad-Remote1.JPG http://www.tvhistory.tv/1957_Zentih_Ad-Remote1.JPG
- jared314 13y agoThere are also reasons they stopped using it in the first place[1]: Some problems with this method were that the receiver could be triggered accidentally by naturally occurring noises, and some people could hear the piercing ultrasonic signals. There was an incident in which a toy xylophone changed the channels on such sets because some of the overtones from the xylophone matched the remote's ultrasonic frequency. While each specific problem could be worked around with modern methods, it looks like a technique reserved for situations where you don't have a better option. [1] http://en.wikipedia.org/wiki/Remote_control#Television_remote_controls http://en.wikipedia.org/wiki/Remote_control#Television_remot...
- Torgo 13y agoI don't see why DTMF https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_sign... couldn't have solved this pretty easily without adding too much complexity. I've seen those remotes before and they usually only had about three buttons on them. Still pointless, but I think this would have worked.
- chrissnell 13y agoWe had a tv like this growing up. Whenever the dog would run through the room, his tags would jingle and change the channel. It was funny, too, because the tv channel changer was this rotary dial that was motorized. When you changed the channel, the little dial on the tv would click and spin around.