Mobile Phone Detector for GSM, 3G and 4G devices

Thread Starter

AviYuv

Joined Nov 12, 2021
1
Hello! I'm doing this side project for a mobile phone detector. I went through many documentation, and built up various circuit but it doesn't work as it said.

Finally I was able to use this circuit diagram to produce the following assemble.
1637166767855.png

My Result:
1637167170450.png

But the circuit works only when it receives a 2G network signal and it have a very limited range approximately 1.4m. It can't detect consistent 3G and 4G signal.

I would love to have this circuit operational for all types of network: 2G, 3G, 4G.
Your help is very much appreciated.
 

Audioguru again

Joined Oct 21, 2019
3,829
A circuit to detect ultra-high cell phone frequencies does not work when built on a breadboard due to the stray capacitance between all the rows of contacts and the stray inductance of the many tangled jumper wires all over the place.

The simple circuit has two low capacitance capacitors feeding a low frequency opamp that does not work at radio frequencies.
 

DickCappels

Joined Aug 21, 2008
7,955
In other words, when I fist saw this circuit years ago I had to wonder who discovered it, circuits like that aren't designed.

Below is one that was designed to detect GHz range telephone signals. It is not very sensitive and only meant to indicate when a phone in very close proximity is transmitting.

1637925437988.png

There are better circuits out there, you just have to look for them.
 
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