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Conversion of electromagnetic radiations to electrical energy

  1. Feb 2, 2010 #1
    conversion of electromagnetic radiations to electrical energy!!!

    hello everyone!!!
    few days before i bought a glowing sticker which sticks near the antenna of my mobile and glow when any call comes to my mobile or when i make any call from my mobile!!!

    All i know about it is that it detects the electromagnetic radiations and glow!!!!

    I want to know how a small size sticker can detects electromagnetic radiations and convert these radiations to electrical energy???:uhh:
     
  2. jcsd
  3. Feb 2, 2010 #2

    berkeman

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    Re: conversion of electromagnetic radiations to electrical energy!!!

    Welcome to the PF. If it's unpowered, I'm not sure how it would do it. Certainly it can be done near a strong transmitter, but your mobile phone does not put out very much power.

    Can you provide a web pointer to more information about this sticker?
     
  4. Feb 2, 2010 #3
    Re: conversion of electromagnetic radiations to electrical energy!!!

    well, i dont have any weblink for it!!!

    the sticker size is very small just like someone engangement ring!!!

    also on searching from various stuffs i got this method for the conversion:

    A system is disclosed for converting high frequency zero point electromagnetic radiation energy to electrical energy. The system includes a pair of dielectric structures which are positioned proximal to each other and which receive incident zero point electromagnetic radiation. The volumetric sizes of the structures are selected so that they resonate at a frequency of the incident radiation. The volumetric sizes of the structures are also slightly different so that the secondary radiation emitted therefrom at resonance interfere with each other producing a beat frequency radiation which is at a much lower frequency than that of the incident radiation and which is amenable to conversion to electrical energy.
    This beat frequency radiation can be transmitted to the converter via a conductor or a waveguide and converted to the electrical energy having a desired waveform and voltage.

    but i dont think that this apparatus is used in these small and cheapy stickers!!!!
     
  5. Feb 2, 2010 #4

    berkeman

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    Re: conversion of electromagnetic radiations to electrical energy!!!

    No, zero point energy (vacuum fluctuations) has nothing to do with your question.

    http://en.wikipedia.org/wiki/Vacuum_fluctuation

    Very interesting subject, and a possible explanation for the accelerating increase in the size of the Universe, but not part of the glowing sticker question.

    Where did you see this sticker? Did it have any name on it?
     
  6. Feb 2, 2010 #5
    Re: conversion of electromagnetic radiations to electrical energy!!!

    well..these stickers are available in markets at very low cost!!!!

    nothing is mentioned on it..well I am from India and these stickers are available from last 3 years(i.e.,not a new advent)!!!
     
  7. Feb 2, 2010 #6

    berkeman

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    Re: conversion of electromagnetic radiations to electrical energy!!!

    Can you take a picture and post it?
     
  8. Feb 2, 2010 #7
    Re: conversion of electromagnetic radiations to electrical energy!!!

    i dont have it now!!

    will post tommorow..
    well may be i think the electromagnetic radiations are converted to the light energy..
    is there any way of doing such conversion..??
     
  9. Feb 2, 2010 #8

    berkeman

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    Re: conversion of electromagnetic radiations to electrical energy!!!

    Sure, but not without some powered amplification when the input is at cell phone power levels. Certainly not are receive power levels!
     
  10. Feb 2, 2010 #9
    Re: conversion of electromagnetic radiations to electrical energy!!!

    ok well what are those methods of coversions..will you please elaborate!!!
     
  11. Feb 2, 2010 #10

    berkeman

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    Re: conversion of electromagnetic radiations to electrical energy!!!

    Flourescent tubes are often used for demonstration. Either next to high-power RF transmitters, or in more artistic applications, under high voltage transmission lines:

    http://scawley.wordpress.com/2008/04/18/uk-the-florescent-field-by-richard-box/
     

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  12. Feb 3, 2010 #11
    Re: conversion of electromagnetic radiations to electrical energy!!!

    They sell these gadgets in London too.

    These things use little antennas feeding small efficient LEDs (I think just using diodes to rectify the RF directly, but possibly they also "cheat" by including a couple of button cells. Most of the tags I've seen on sale look too small for this). These LEDs can be surprisingly bright with just a few milliwatts, and remember that a phone puts out vastly more than that when making a call - the sticker will be within a few cm of the phone's antenna. It's a bit daft, in my opinion, to waste expensively bought battery transmitter power in this way.

    The incoming call mystery is solved because the phone's transmitter is activated whenever an incoming call is detected, even before the user answers the call. Thus the phone's handshake reply lights the tag, not the distant signal.
     
    Last edited: Feb 3, 2010
  13. Feb 4, 2010 #12

    berkeman

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    Re: conversion of electromagnetic radiations to electrical energy!!!

    Ah, thanks for that, Adjuster. I didn't think about the 2-way handshake angle for the incoming call. Do you maybe have a pointer to a typical device?
     
  14. Feb 4, 2010 #13
    Re: conversion of electromagnetic radiations to electrical energy!!!

    Here is one which claims not to need a battery (maybe that just means the battery is a fixed part of the item - not replaceable?) http://www.diytrade.com/china/4/products/4971551/flashing_sticker_mobile_phone_flashing_sticker.html [Broken]

    Here are some more - http://www.sz-wholesale.com/p/Mobile-Phone-Flasher/Mobile-Phone-Flashing-Stickers-28722.html

    And some that do admit to needing batteries http://www.alibaba.com/product-gs/240075264/Mobile_phone_Senser_LED_Flasher.html

    By the way, I've looked in vain for schematics,if you manage to track one down I'd be interested to see it.
     
    Last edited by a moderator: May 4, 2017
  15. Feb 5, 2010 #14

    turin

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    Re: conversion of electromagnetic radiations to electrical energy!!!

    I wouldn't be so sure about this. I have seen a frequency counter go berzerk at an incoming cell-phone call. And the input to the frequency counter was not an antenna, but rather wired to a bread board. The cell phone was sitting on the work bench several feet away.
     
  16. Feb 5, 2010 #15
    Re: conversion of electromagnetic radiations to electrical energy!!!

    According to the UK Health Protection Agency, the maximum output power for a cellphone is up to 2W peak (250mW average) at 900MHz, or 1W peak (125mW average) at 1800MHz - see link.
    http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1195733844923 [Broken]
     
    Last edited by a moderator: May 4, 2017
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