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Mobile Phone Detector

Mike McKean
Hi,

If anyone can help me, or explain this, I'd appreciate it. I normally like to understand what I am doing, but on this occasion, I just don't. But I found several different Youtuibes and Diagrams that all used trhe same I.C. But it just does not make sense to me.


I am building a mobile phone detector. I have ordered some parts, based on some web-based reserach I have done. So too late to change. But the parts cost pennies so it's just my time I am potentially wasting.


If mobile phones operate at about 0.8 GHZ to 3.4 GHZ, then I'd expect to build soemthing with a receiver that is a tuned circuit, or several different tuned circuits, but operating at those frequencies. But the I.C. everyone seems to be using is the LM386, which is an audio amp?  I just don't understand it?


I want to detect a mobile phone in "idle", i.e. even when it is not actively mbeing used.


I attached my roiugh working notes which include a couple jpeg diagrams that I am using as references.


Any help appreciated, I am building it anyway. But if anyone has a better solution, or any guidance, I'd be pleased to be educated. Thanks, Mike
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    Hi Mike - the 2nd circuit you attached appears to be a broadband RF diode-detector, followed by an audio amp IC which is used to amplify the tiny detected signal to be large enough to light an LED.

    Such diode detectors can be very broadband if they are designed well.

    They are not very sensitive and will only detect fairly large signals.  Also, unless you include some filtering, it will detect all signals picked up by the antenna.

    If you actually wanted to detect (or even block) a phone, a cunning way to do it is to trick it into connecting to a local fake base station - advanced stuff!
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  • 0
    Hi Mike - the 2nd circuit you attached appears to be a broadband RF diode-detector, followed by an audio amp IC which is used to amplify the tiny detected signal to be large enough to light an LED.

    Such diode detectors can be very broadband if they are designed well.

    They are not very sensitive and will only detect fairly large signals.  Also, unless you include some filtering, it will detect all signals picked up by the antenna.

    If you actually wanted to detect (or even block) a phone, a cunning way to do it is to trick it into connecting to a local fake base station - advanced stuff!
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