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Bracelet That Pings A Nearby Ring [Help]

Discussion in 'General Electronics Discussion' started by Maxride17, Oct 26, 2015.

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  1. Maxride17


    Oct 26, 2015
    First, I have a question.
    How does that phone case that harnesses radio waves and converts them into electricity work?

    I'd like to build a few myself, for non-commercial use.

    I want to create a bracelet that charges a capacitor (Via the "charger" above), and once charged, sends out a frequency that can be picked up by a much smaller device inside a ring, that takes the signal, makes the ring glow (LED), and then bounces the wave back, making the bracelet light up as well. Is this possible?

    Also, would it be possible to create a custom feature? It is:
    I can change an on/on/on/on switch, and depending on which "on" position it is in, it sends a different wave, to be interpreted by the ring, and it chooses a different color depending on the frequency.
    The goal of the bracelet/ring combo is that 2 people will know when they are near each other, without texting, and to add a bit of fun to our lives. It's going to be a present for my girlfriend's birthday in a few months.

    Thanks for any and all serious responses!
  2. Alec_t


    Jul 7, 2015
    Welcome to EP!
    Even if you have access to a micro-assembly robot I'm afraid this project isn't practical :(. The Laws of Physics are against you, in that any RF energy harvested will be incredibly low and unlikely to be able to turn on an LED, yet alone power a transmitter.
  3. Maxride17


    Oct 26, 2015
    Dang. Well, thanks anyways then! Do you have any ideas for high efficiency alternatives to the radio-wave conversion? Or should I just go with a Watch battery? I'd rather not do that though. :- |
  4. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    You should think along the lines of a Fitbit Flex bracelet, but with a Bluetooth transceiver inside each bracelet. This is not an easy task, but it is doable. Power the bracelets from rechargeable Li-ion batteries. It would be barely possible to "reverse engineer" a Fitbit bracelet to retain the five little LED display lights and the bracelet while replacing the rest of the internal electronics with a Bluetooth transceiver and your own microprocessor. This is not a task for an electronics novice.
  5. Maxride17


    Oct 26, 2015
    Alright, thank you. I'll see what I can do.
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