Mobile Scanner Circuit

Here is a device to locate the mobile phone. It emits intermittent flashes and beeps to indicate the presence of an active mobile phone. The circuit becomes active even if the mobile phone is in silent mode. It can be used to detect mobile phone call in noisy environments. Range of the circuit is 15 cm.

The circuit is basically an RF detector. During the activation of mobile phone, strong RF field will be generated. The sensor coil L detects the RF signals and T1 amplifies the signals. The amplified signals are given to the clock input of IC1. CD 4017 is a Johnson decade counter IC with 10 outputs. Its clock input pin 14 is highly sensitive to RF pulses so that it is a very good choice for RF detection. Only two outputs (Q1 andQ2) of the IC are used while the Q3output is tied to the reset pin 15 so that IC will reset on every third pulse.

This will repeat the activation of LED and Buzzer. When the sensor detects the RF signal, clock input of IC1 gets pulses and its output pins 2 and 4 becomes high and low alternately giving flashing lights and beeps. The coil used in the circuit is a ready made inductor.Buzzer used is a small piezo buzzer.

Mobile Scanner Circuit diagram


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  • isaac

    please can it detect when the phone is switch on and not in use. Please

  • Ali Omer

    @ Author – D.Mohankumar
    I am Ali Omer from Karachi, Pakistan. I am doing my B.E (Electronics). You have mentioned about the inductor. For the sake of explanation, would you please help me about which type of inductor is to be used?

    please acknowledge.
    That would be so kind of you.

    Best Regards.

  • ranbir singhania

    hello sir,i m in 3rd year EEE branch..
    i wanna know how to make a circuit.i.e. i have a lot of ideas & i m unable to implement these ideas..some of them relate to circuit this is my kindly request to u to guide me….
    plz tell me from where i should start circuit designing..
    tell me the steps to be a circuit designer.plz.

  • faraz

    hello sir,,sir plz will you plz send me the diagram of mobile numbers detector/scanner….

  • a.m.h

    for similar projects coil is very important and must be careful…
    if we can change coil or ant. character, we can use any amplifier such as lm386 for detect RF field in wide range of frequencies

  • ashish dixit

    sir i just want the component of the circuit and its working…………………
    from where i can get it easily in proper manner


    hello sir. the mobile scanner project doesnt using BC543 instead of is case it may be the problem…………….

  • bloom

    hi, we cannot find a built-in 10mH inductor… can u help me with this problem?

  • ashwin r

    how can we increase the range

  • D.Mohankumar

    The circuit is a simple RF detector with short range around 10-20 cms.CD 4017 IC has very sensitive input that readily accepts pulses.To detect the RF energy and converting them in to DC pulses, the transistor amplifier is used.The main element is the ready made Fixed inductor( one like resistor). Do not use a coil inductor.To test the circuit, disconnect the link between the collector of transistor and pin14 of 4017. Then take the circuit near an AC wire.LED will blink and buzzer will beep.Then connect again with the transistor collector.

    • swetha

      sir, i am swetha studying final year. what are the units of this capacitor in this circuit diagram?and which type of inductor is used?how can we increase the range of this circuit?

    • sneha

      sir wat is the substitute for the inductor plz reply