Collect and analyze ECG data

ecg

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.

14 thoughts on “Collect and analyze ECG data

  1. Be VERY careful with this, you will have a really good electrical connection to some very expensive equipment that’s really hard to replace.

    For the dense of you: That means you could easily die from simple mistakes with this.

    Some opamps will output the supply voltage if ony one half of the powersupply is hooked up.

    If the PC is improperly grounded, you’ll get several hundred volt on the chassis.

    Safety is hard, you don’t want to be hooked up to an good path to ground if you happen to touch a live wire, but on the other hand you want to ensure that any nastyness coming in via the output isn’t allowed to flow into the test subject.

    I’d probably not feel safe unless:
    * The output was run though an optoisolator.
    * The inputs are all clamped to common using diodes, so it’s absolutely certain that the device can’t output more than 0.7 V even in the worst case failure mode.
    * The entire device should be packaged securely in an isolated case, so no lose wires can poke into it.

  2. People tend to freak out about safety issues with this project. Being safe is good, but you have to be CONSISTENTLY safe! If I made a battery-powered tone generator circuit which outputted a sine wave to the microphone jack of the sound card, would people be jumping up and down warning people not to build it because if they touch the wrong locations they could die? The ECG functions fine using a light touch with a single finger of each hand (you don’t need high conduction chest leads). I fail to see a significant difference. If you’re obsessed with safety, more power to you! … but apply the same logic to all your projects

  3. anyone know of a diy sensor that measures brain waves?

    Something like what’s used in sleep centers, or on the myzeo?

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