Although we’ve covered DIY ECGs before, [Scott Harden] sent in his version that gives an in-depth explanation of what to do with the collected data. He built a basic battery-powered op-amp-based ECG for under $1. The circuit just amplifies the signal from the chest leads and feeds it into a computer via the microphone port. He then used GoldWave to record, filter, and save the signal. From there, he used python to analyze the heartbeat and calculate his heart rate and further manipulate the data. His previous blog posts go into more detail on how the python code works and why he chose software over hardware filters.

[Marcus] sent in his work on making ECGs. His first one was inspired by [Jason]’s. Believe it or not, you can build this thing for under $5. After getting it semi-functional, he decided to pick up a cheap one and mod it for PC input via the sound card. (There are plenty of sound card oscilloscope projects that will work for this.) Remember kids, don’t go sticking electrodes on anyone unless you know what you’re doing: correctly placed electrical shocks (even low power ones) can be deadly.