Comment on 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 ...

CBProjects@lemmy.world ⁨11⁩ ⁨months⁩ ago

• LastYearsPumpkin@feddit.ch ⁨11⁩ ⁨months⁩ ago

  Back in 1956, the Zenith TV remotes didn’t require a battery and just used the power generated by pushing the button. They were severely limited in the number of buttons available though, due to the technology of the time.
  theverge.com/…/zenith-space-command-remote-contro…

  source

  • henchman2019@lemmy.world ⁨11⁩ ⁨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.

    source
• evident5051@lemm.ee [bot] ⁨11⁩ ⁨months⁩ ago

  My Xiaomi doorbell button works the same way.

  source