Build your own Wireless Stethoscope with Arduino and HC-05 Bluetooth

This wireless stethoscope project captures acoustic bodily sounds using a physical stethoscope tubing coupled with a condenser microphone, which converts sound waves into weak electrical analog signals. Because biological sounds like heartbeats are very faint, the signal must be conditioned before processing. The core of this analog conditioning is the NE5532 operational amplifier, configured alongside several resistors (1K, 3.3K, 10K, and 100K values) and capacitors (470nF and 2.2uF) to form an active filter and amplification network powered by a dual polarity power supply. This dual rail supply allows the op-amp to handle both positive and negative voltage swings of the audio waveform without clipping. Once amplified and filtered, the analog audio signal is routed to an Arduino Mega 2560 (or Arduino UNO) which can digitize the signal or transmit it wirelessly. To achieve wireless functionality, an HC-05 Bluetooth module is interfaced with the microcontroller to stream the data over a wireless serial link. Finally, a Bluetooth Serial Terminal Android Application receives this data stream on a smartphone or mobile device, enabling a user to monitor heart rates and listen to auscultation sounds remotely without being physically tethered to the patient by traditional analog tubing.