People have their own ambition during childhood. When the teacher is asked about their dream, some of them said they would like to become a police, lawyer, engineer or doctor, after they’ve grown up!

Talking about doctor, we knew that the most common thing of a doctor is the stethoscope that always hanging around the doctor’s neck. By the way, according to the trusted fact, doctors have used the acoustic stethoscopes since two hundred years ago. Normally, it used by doctors to listen the blood flow in arteries and veins.

Beside that, engineers are using the stethoscopes to check scientific vacuum chambers and for other small-scale acoustic monitoring tasks.

Nowadays, the electronic stethoscopes are becoming increasingly popular. To be honest, it’s easier to hear heartbeat and lung sounds with an electronic stethoscope than acoustic stethoscope! In addition, some of the advanced electronic stethoscope allows the user to record and playback the data (heartbeat and lung sounds) for reference or as a teaching method.

Today’s project is about a very simple yet cheap electronic stethoscope. All you need here are:

  • A US$3 spy ear, and

  • As simple 3 transistor amplifier.

Well, just attached the stethoscope in the end of a simple 3 transistor, like it shown on the below figure. You’re done and can use it to listen your heartbeat instantly!

Electronic stethoscope

Hope you’ll try out this project with your children, as you can educate them while you’re building the electronic stethoscope.