Saturday, May 25, 2024

Long Range Audio Spy Device

Bluetooth-based spying devices can help you eavesdrop on someone, just like in James Bond movies. But Bluetooth and also WiFi have a very low range. Wouldn’t it be cool if you can secretly hear a person or organisation’s criminal plans and take timely action to stop them?

 So today, you will learn to make a device that will help you to spy on dangerous people without requiring you to be within range. Since the device works on GSM technology, any person in one country can easily spy on another person in a different country. Another feature of this device is that its small size enables it to be easily hidden.

Because the device is meant for security purposes only, its use is not recommended for any other intent.

Bill Of Material 

Begin the project by collecting the following items:

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First, you will need to install the FONA library in the Arduino IDE, which will establish communication of AT commands to SIM 800l. The subsequent connection will enable the incoming call on the GSM module to be automatically received for audio transfer of the entire conversation.


Include the FONA library in the code, and then define the RX and TX pins for SIM800l. Next, create a setup function with a baud rate of 4800 for starting the software serial port of the SIM 800I.

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After this, create a loop function that will check the incoming call. When an incoming call is detected, it will automatically be received and the attached mic will turn on. Now, as the audio signal is being captured, it will be transferred over a GSM network to any faraway place. This will enable you to remotely listen to someone’s conversation secretly. 

Fig 2.
Fig 3.
Fig 4.


Connect the RX pin of SIM 800l to pin 10 of Arduino Micro and TX to pin 11.

Then connect the SIM 800l MIC N pin to the negative pin of the microphone sensor and SIM 800I MIC P to the microphone’s positive pin. 

Fig 5.Connection



After finishing all connections, power the device either with USB or with a 4 to 5V battery. Then deploy the device near a person, which you want to spy on. Now, make a call on the SIM800l. It will be automatically received and transfer of the voice signal to your phone will begin.

Download Source Code

Ashwini Sinha
Ashwini Sinha
A tech journalist at EFY, with hands-on expertise in electronics DIY. He has an extraordinary passion for AI, IoT, and electronics. Holder of two design records and two times winner of US-China Makers Award.



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