Questions regarding operation of phone detector circuit

Thread Starter


Joined Jun 21, 2018

I am getting into electronics and am in building my first circuit. As I'm big into mobile technology I figured I'd build a cell phone detector using the following "guide":

The circuit diagram can be viewed here:
I have some questions regarding how the circuit works and as the creator of the circuit won't reply I'ms wondering if any of the users here would be so kind as to assist me in understanding how the circuit operates.

The circuit itself is dependant on mutual induction in the coil induced by the phone emitting frequencies in the cellular frequency range. Is this actually feasible with the phone operating as a coil inducing induction simply by being placed nearby the coil in my circuit? I'm having a hard time wrapping my head around this. As for the rest of the circuit, am I correct in assuming that the Schottky diode will rectify these high frequencies to the transistor which will amplify the voltage and trigger the comparator in the opamp making the LED glow?

It would be greatly appreciated if anyone could be of help!


Joined Apr 5, 2008

As there is no tuned input circuit, the detector will see all RF signals in the naberhood.
Also the sensitivity will be very low, as stated on the site.