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DIY ECG Improvements


I have simplified and improved my ECG machine design! Check out the new post:


No 3-day weekend would be complete without a project that’s, well, virtually useless. I present to you my new and improved ECG machine! Instead of using a single op-amp circuit like the previous entries which gave me decent but staticky traces, I decided to build a more advanced ECG circuit documented by Jason Nguyen which boasted 6 op amps! (I’d only been using one) Luckily I picked up a couple LM 324 quad op amp chips at radioshack for about $1.40 each, so I had everything I needed. I’ll skip to the results. In short, they’re gorgeous. Noise is almost nothing, so true details of the trace are visible. I can now clearly see the P-Q-R-S-T features in the wave (before the P was invisible). I’ll detail how I did this in a later entry. For now, here are some photos of the little device and a video I uploaded to YouTube. It’s not fancy.

UPDATE: Upon analyzing ~20 minutes of heartbeat data I found a peculiarity. Technically this could be some kind of noise (a ‘pop’ in the microphone signal due to the shuffling of wires or a momentary disconnect from the electrodes or perhaps even a static shock to my body from something), but because this peculiarity happened only once in 20 minutes I’m not ruling out the possibility that this is the first irregular heartbeat I captured with my DIY ECG. Note that single-beat irregularities are common, and that this does not alarm me so much as fascinates me. Below is the section of the data which contains this irregular beat.

About the author

Scott W Harden

Scott Harden has had a lifelong passion for computer programming and electrical engineering, and recently has become interested in its relationship with biomolecular sciences. He has run a personal website since he was 15, which has changed names from HardenTechnologies.com, to KnightHacker.com, to ScottIsHot.com, to its current SWHarden.com. Scott has been in college for 10 years, with 3 more years to go. He has an AA in Biology (Valencia College), BS in Cell Biology (Union University), MS in Molecular Biology and Microbiology (University of Central Florida), and is currently in a combined DMD (doctor of dental medicine) / PhD (neuroscience) program through the collaboration of the College of Dentistry and College of Medicine (Interdisciplinary Program in Biomedical Science, IDP) at the University of Florida in Gainesville, Florida. In his spare time Scott builds small electrical devices (with an emphasis on radio frequency) and enjoys writing cross-platform open-source software.

Permanent link to this article: http://www.SWHarden.com/blog/2009-01-20-diy-ecg-improvements/


  1. Greg B

    You mention LM324 op amps, and judging by the number of pins in the picture, look like you’re using LM324, but the schematic (bigsch1.gif) shows all the op amps as LF353N??

  2. steve chapel

    Interested in updating the little ekg a bit? I am getting ready to build the basic circuit and add a bit of gee-whizz to it. I am going to make mine wireless, thus eliminating the ground loop problems you have struggled with. It also allows freedom of movement. I have the resources to make some PC boards so I plan on using surface mount parts wherever possible on the final version. I expect to have a transmitter about the size of a IPOD, and a receiver that attaches to my laptop that is essentially a dongle. Future enhancements may include a voice recorder interface so I can go to the gym and later download the results for analysis.
    Interested in being involved in this project? I have not been able to contact Jason Nguyen, seems his e-mail has changed.
    BTW, Great work on your project!


  3. Daniel Golan

    Hello Scott, I saw your video on the ECG circuit, will be very thankful if you could send me the circuit schematics to my mail :danielgolan85@walla.com
    Thank you very much

  4. YOELK

    Hi, i need to build and ECG and i have no idea. Could you please send me the circuit and the code? Thanks. yoelkrca@gmail.com

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