Circuit to steal EMF?

Discussion in 'General Electronics Chat' started by cjdelphi, Jun 11, 2009.

  1. cjdelphi

    Thread Starter New Member

    Mar 26, 2009
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    I watched an episode of the Gadget Show which showed a small circuit which lit up the led and fed off the power from the microwaves coming in and out of a cell phone converting RF to Electric, I had a look for a circuit to do that but found nothing, is there some kind of secret underground world of EMF electronics going on?...

    Thanks...
     
  2. mkbutan

    Senior Member

    Sep 30, 2008
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    IF YOU HAVE SEEN THE GADGET THEN YOU MUST HAVE NOTICED THAT THERE IS A COIL LIKE ANTENNA AS A RECEIVER FOR THE CKT
    IT RECEIVES RF/MV AND CONVERT IT TO THE ELECTRICAL SIGNAL
    AS YOU KNOW THAT IS EMF THEN YOU MUST BE KNOWING THE PROPERTIES OF EMF
    DO SOME THING GOOD DON'T JUST........
     
  3. Jolly

    New Member

    Jun 11, 2009
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    i agreed :)
     
  4. Mike Mandaville

    Active Member

    May 27, 2009
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    If you live close enough to a high power line, picking up electricity through wireless means should be easy enough.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    If you live close enough to a power line, you can even steal a little power, enough for a small light bulb. It is enough to get you into legal trouble, in the USA it is call "Theft of Service". I doubt they would notice an LED though.
     
  6. mkbutan

    Senior Member

    Sep 30, 2008
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    ha ha ha aaaaaaaaaaa
    good
    do the us agencies have time to see the LED powered wireless le he he heeeeee
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    It's actually pretty easy to do. Wind a coil, a big one, and that should do it. If you want to enhance the effect add a capacitor, and try to make it resonant to whatever the line freq is in your area.

    I'm describing this only for experiment. I'm not joking about it being illegal, many a farmer whose barn was next to high power lines and figured they would never notice that small light bulb found out it is not a joke. The power companies take losses seriously, partly because it could be a safety issue.

    High tension lines throw out quite a field.
     
  8. Mike Mandaville

    Active Member

    May 27, 2009
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    This reminds me a little of the television police in the UK. Someone in another thread mentioned that the government does not charge for listening to the radio, I think. This is not true in England.
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    Yeah, when my Dad was stationed at Lakenheath Air Force Base in the early 60's we had to pay for the privilege, but I got to see the premier of Dr Who! I was raised an Air Force brat.

    We have a lot of UK members here. Maybe they could tell us the legalities of a crystal radio?
     
  10. mkbutan

    Senior Member

    Sep 30, 2008
    270
    16


    you are 100% right
    we use to play with the coils in our school days
    believe me it can dangerous to the life
    you have to take preoccupations first
    especially who don't know the statics & emf power's
     
  11. bertus

    Administrator

    Apr 5, 2008
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  12. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    You can buy these commercially from the phone gadget suppliers. I've even seen cellphone covers with little leds in that light up when the phone rings.
     
  13. cjdelphi

    Thread Starter New Member

    Mar 26, 2009
    272
    2
    Nah they just detect the increase in microwaves coming out of the phone and flash on and off with their own power source, i'm talking about taking those microwaves and stealing their energy to charge the phone or light up an LED etc etc
     
  14. leftyretro

    Active Member

    Nov 25, 2008
    394
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    Works in theory but not very practical. RF radiation power decreases at the square root of the distance, so very little practical power is available for 'harvesting'.

    Lefty
     
  15. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Actually they are powered by the phone's microwave energy with little antenna wires built in. It's enough power 2 inches from the phone antenna to light a few small leds.

    Check the phone gadget suppliers.
     
  16. Wendy

    Moderator

    Mar 24, 2008
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    Phone microwave energy to charge the battery?

    Uhoh, another HHO scheme. Tapping into other source maybe.

    Also a good way to have your signal abrubtly disconnect. That energy was meant to be used for something else.
     
  17. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Hi.
    The harvesting of electromagnetic fields from power lines and broadcasting in general to produce 'some' energy to recharge a battery was a subject discussed in another forum years ago, and somehow the final thought seemed that tuning into resonance to the most powerful/nearby source of EMF would not be the optimal approach.

    I remember little details, but went towards plain rectification at the end of a long wire, to capture all radiation at all frequencies. Any opinions on this?

    Such long wire would not apply on a portable unit.

    In this subject of picking the EMF from the air, I have a doubt on how to tap energy from resonating circuits:

    A parallel resonant

    A-------||---------G
    A------coil--------G

    A series resonant

    A-------||-----coil-------G

    being A an antenna and G ground,

    Where/which/how is it more convenient to tap/insert rectification ? How would you do it ?

    One resonant circuit will have low voltage and higher current; the other higher voltage at low current
     
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