Inspired by a photoresistor-based pulse sensor designed by MarkusB from Let’s Make Robots, MAKE’s Technical Editor Sean Michael Ragan set about to build the IR Pulse Sensor using infrared emitter and detector diodes. The latest addition to our beginner-friendly Weekend Projects series, the IR Pulse Sensor is a unique combination of hardware and software, and it’s a great all-around project for learning.
We’ll start with scoring and snapping a multipurpose PC board to fit the circuit’s footprint. Sand down the sharp corners and sides you don’t need to make a truly custom board.
We’ll use a standard cable clip as a finger cuff, so that your finger will easily rest upon the diodes in order to detect your pulse.
Some simple modifications to the LM324 op-amp IC will be done in combination with a simple circuit soldered to the PC board before moving on to the software.
Output from the pulse sensor will input on the A0 pin header on the Arduino, and raw data from the device can be seen using the software sketch provided on MAKE’s GitHub repository. Lastly, Processing will be used to visualize that data and render it as a pulse on your monitor.
Whether you consider yourself a soldering whiz and want to learn a bit more about the Arduino and Processing, or vice-versa, or if you simply want to dive in and learn software and hardware, the IR Pulse Sensor is a great project to get started with.
Watch the video below to see this project in action. It only takes a few hours to build and then you can use this project for novel applications. Some ideas include matching musical beats to your heartbeat, triggering other devices with a specific pulse rhythm, or simply turning that beat into an audible sound. If you modify this project be sure to document your process and send us a story about your build – you could be featured on the MAKE blog!