Serious question from a beginner in electronics. For reasons I do not fully understand, I have become fixated on the idea of collecting small amounts of electricity from ā€œinterestingā€ sources. I donā€™t mean ā€œfree energyā€, instead, I mean things like extracting a few mV from being so close to a AM radio tower using two tuned loop antennas in phase with each other, or getting a few mV from the rainā€™s kinetic energy with PTFE and using two electrodes which are shorted when a drop of rain hits it. In short, Iā€™ve done small experiments to confirm that I can get a few mV and enough to get me excited but not much more. I know Iā€™m not going to get much power out of this, but Iā€™ve been able to charge a NiMH battery a few mV by being a quarter mile from an AM radio station with my antenna setup. It would be fascinating to me if I could store these small charges in something like a 5V USB power brick eventually.

The smarter idea would be for me to harvest energy with the sun or from the wind or a stream. Iā€™m tinkering with this as well, but larger amounts of electricity scare me for right now. I guess Iā€™ve seen enough experimental sources of harvesting electricity and Iā€™ve gotten the itch to invent, which is a dangerous itch for a newbie like me to have.

The best advice Iā€™ve seen online (ok, it was ChatGPT) is that itā€™s just not worth it to work with such small amounts of electricity, because the equipment required is too expensive and sophisticated (e.g, devices to read the charge of a capacitor without discharging it) to make anything thatā€™s efficient enough to be worthwhile. Would you agree? Do you know of some other fascinating source of gathering electricity that I should also waste lots of time on?

I just have all these electronic components and magnets and when I move them together the numbers on multimeter get bigger. itā€™s neat.

  • 2 Nut November@sh.itjust.worksOP
    link
    fedilink
    English
    arrow-up
    1
    Ā·
    1 year ago

    Oh yeah, I hear you on LLMs. Technically, ChatGPT has not ā€œheardā€ of anything. Itā€™s generally something I use as a jumping-off point when Iā€™m desperate and donā€™t know what search query to use.

    Does passive RFID harvest its power? I donā€™t know much about RFID (Iā€™ll probably head over to wikipedia after this comment) but I figured that it was a circuit that, when given a bit of energy from a reader, sends back an RF signal with an encoded ID and that in the absence of that powered reader, the RFID device wouldnā€™t be transmitting anything.

    • charmed_electron@programming.dev
      link
      fedilink
      English
      arrow-up
      7
      Ā·
      1 year ago

      Yes, the circuit in an rfid device gets its power by harvesting energy from the RF source itā€™s being illuminated with. A smaller version of wireless power transmission first invented by Tesla (the person, not the car company). Similar principles were used in the Cold War for surreptitious listening devices. Neat tech.

    • usrtrv@lemmy.ml
      link
      fedilink
      English
      arrow-up
      5
      Ā·
      edit-2
      1 year ago

      The most basic RFID tags will just send back an ID. The complexity can shoot way up and have all sorts of integrated circuits, mostly around encryption.

      I guess itā€™s more of a semantic argument at this point, but would you not consider a tiny computer (RFID tag) that powers itself solely off of radio waves not a form of energy harvesting?

      • benzmacx16v@discuss.tchncs.de
        link
        fedilink
        English
        arrow-up
        5
        arrow-down
        1
        Ā·
        1 year ago

        I would say ā€œenergy harvestingā€ is when the receiver and transmitter are not designed to be used together and they are not physically close together. Otherwise your electric toothbrush and Qi charger might count.

        • usrtrv@lemmy.ml
          link
          fedilink
          English
          arrow-up
          2
          Ā·
          1 year ago

          Thatā€™s a good point. What about long range RFID skimmers? You could argue the tag wasnā€™t designed to work with a skimmer. I guess thatā€™s more like energy injecting?

      • 2 Nut November@sh.itjust.worksOP
        link
        fedilink
        English
        arrow-up
        1
        Ā·
        1 year ago

        I guess the difference for me would be how long it stores that energy for, but the difference is probably semantic and easily changed with a few capacitors.

        • usrtrv@lemmy.ml
          link
          fedilink
          English
          arrow-up
          6
          Ā·
          1 year ago

          They do use capacitors to keep power. Hereā€™s a simplified diagram: