This instructable shows you how to make an electrocardiograph and a heart rate monitor. It is intended to be a fun science project only. Of course, it should not serve as a medical purpose.
PLEASE NOTE : To avoid any risk of electric shock, only use battery implementation. Electrodes are theoretically isolated from the circuit by the instrumentation amplifier, but play safe. Maker is not responsible for any accident that may happen.
This is a simple design that fits on a single breadboard. You are free to experiment and to custom it for your needs.