Researcher has developed, at a cost of less than one dollar, a wireless light switch that runs without batteries, can be installed anywhere on a wall and could reduce the cost of wiring a house by …::A U of A engineering researcher has developed a wireless light switch that could reduce the cost of wiring a house by as much as 50 per cent.

  • henchman2019@lemmy.world
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    7 months ago

    Those worked by sound. No power was needed or generated by the remote.

    From the article…

    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.

    I THINK I even remember, way back, random channel changes from tapping on a drinking glass or something similar… Cool tech for the time