Simple Mobile Phone Detector Using LM358

In this tutorial, I will show you a simple mobile phone detector project using a cheap LM358 op-amp. This mobile phone detector can detect the nearness of an active cell phone from a separated distance of four to five meters. So it can come helpful in an assessment lobby or gatherings where cell phones are not allowed.

The mobile phone detector circuit can recognize approaching and active calls, SMS, internet, and video transmissions regardless of whether a mobile phone is kept in quiet mode. At the point when it recognizes an RF signal from an initiated mobile phone, its LED begins flickering and keeps on flickering until the signal stops.

Circuit Diagram

mobile phone detector

Components Required

  • LM358 IC
  • BC548 NPN Transistor
  • 100 uF/25V Electrolytic Capacitor
  • 1uF/25V Electrolytic Capacitor
  • Resistors (1 KΩ, 220 KΩ, 100 KΩ)
  • 100K Potentiometer
  • Led
  • Antenna
  • Connecting Wires
  • 5V Power Supply

Circuit Connection

In this mobile phone detector, at first pin 8 and pin 4 of the LM358 op-amp are directly connected to the Vcc and ground respectively.

Pin 3 is connected to the ground through a 100 uF electrolytic capacitor and also connected to the Vcc through a 220 KΩ resistor. Pin 3 is also connected with pin 2 through a 1 uF electrolytic capacitor.

A 100 KΩ potentiometer is taken and its right terminal is connected with pin 1 and the left terminal is connected with pin 2 and the middle terminal is connected to pin 1 of the op-amp IC.

An NPN transistor of its base terminal is connected with pin 1 of the IC. Another collector and emitter terminal are connected with Vcc through a 1 KΩ resistor and cathode of the LED respectively. The anode terminal of the LED is directly connected to the ground.

Pin 2 is connected through two capacitors parallelly and also with a 100 KΩ resistor to the ground. An antenna is connected also from pin 2 of the IC.

A 5V power supply is attached to the circuit to distribute the required power.

Working of Mobile Phone Detector

At the point when a mobile phone is activated, it radiates an RF signal that goes through close by space. The signal contains electromagnetic RF radiation from the cell phone. 

Capacitor C1 is utilized in the circuit to distinguish the RF signal from the cell phone. At the point when the cell phone radiates RF signal, C1 retains it and gives it to the contributions of IC. This is shown by the flickering of LED. Potentiometer VR1 is utilized to change the scope of the circuit. Transistor T1 is utilized to intensify the signal got at pin 1 of the IC. 

This mobile phone detector circuit is appropriate for 2G systems, GPRS, and network search. It doesn’t identify 3G, WCDMA, and HSDPA networks so well.

Application of Mobile Phone Detector

This mobile phone detector can detect the nearness of an active cell phone from a separated distance of four to five meters

It can come helpful in an assessment lobby or gatherings where cell phones are not allowed.

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