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   Today I learned (todayilearned@noc.social)'s status on Friday, 15-Sep-2023 09:25:41 JST Today I learned

   TIL: Early wireless TV remote controls (1956), commonly known as "clickers", didn't have batteries or electronics. When you clicked the button, an ultrasonic sound was emitted by the button striking the bar. This sound was picked up by the TV to operate it.

   https://en.wikipedia.org/wiki/Remote_control
   #til #todayilearned
   https://www.reddit.com/r/todayilearned/comments/16iun1c/til_early_wireless_tv_remote_controls_1956/