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Blinking lights with RF from nearby cell phone antenna

Discussion in 'Radio and Wireless' started by fraxinus, Dec 11, 2016.

  1. fraxinus

    fraxinus

    3
    0
    Dec 11, 2016
    Hello,
    I have one idea from some years. In front of my windows about 80m away there is a cell phone antenna. It look like the RF is enought to interfere a cheap FM radio / the good ones doesn't. So is it possible to make simple circuit with transistor amplifying and a little led lamp to blink with a rhythm of impulses radiating from an antenna of course with power suply from battery. No practical use just an interesting circuit.

    Excuse me for my poor grammar in English.
     
    Last edited: Dec 11, 2016
  2. Externet

    Externet

    697
    142
    Aug 24, 2009
    My hotspot device for internet wears a led collar and turns it on when there is activity.

    The 'collar' is a 5cm diameter wire loop in series with a Ge diode and a LED. Try if a nearby enough cell tower does anything. I do not think so. They cannot be beyond 5 Watts.
     
  3. cjdelphi

    cjdelphi

    1,098
    104
    Oct 26, 2011
    A series of low voltage drop diodes stood up on their legs in series and an LED works fine for older 2G signals from your phone but 3g/4g don't work as it's a much shorter wavelength

    But considering how close you are you might need a resistor on the led lol
     
  4. fraxinus

    fraxinus

    3
    0
    Dec 11, 2016
    I try this one darlington_mobile.gif
    But it didn't work ,when there is a ringing phone nearby it shine but cannot detect RF from the antenna. If I put one more transistor and replace led with a piezo speaker I can hear impulses but i cannot make led blink.
     
  5. BobK

    BobK

    7,572
    1,633
    Jan 5, 2010
    Why would you expect the LED to blink? If that circuit works at all, it would simply light the LED whenever a sufficiently strong radio signal was detected.

    Bob
     
  6. fraxinus

    fraxinus

    3
    0
    Dec 11, 2016
    this is what it does. And only when there is a phone nearby. The signal from outside is weeker and cannot light the led. I wonder if there will help conecting more of that cirquits with a capacitor and diode /left part only/ in series like a battery?
     
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