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  • Super Simple Electrocardiogram (ECG) Circuit

    Link has moved to http://www.swharden.com/wp/category/electronics/di...

    Our chat is getting too long. My comment meant "good enough for experimentation use" not medical diagnostic use. The article I was unable to find wasn't on Instructables after all. It's at https://blog.adafruit.com/2016/08/31/electrocardio... I am a physician too, not an engineer, British but now live in Switzerland. I do Patient Safety in the pharma industry. My best claim to fame is that I nearly invented Windows, but unfortunately didn't realise how revolutionary it was - things could have worked out rather differently ...

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  • Super Simple Electrocardiogram (ECG) Circuit

    I described a chest lead, not aVL.Your 'fake ground' is properly called 'Goldberger's Central Terminal'. It's all described nicely in the Wikipedia linked from the original article - ie https://en.wikipedia.org/wiki/Electrocardiography For measuring the the chest leads V1-V6 the exact ground does not really matter, and using the two wires connected to right arm and a leg will be quite OK.The main quality issue with this circuit is that the author has not implemented a low-pass filter to get rid of the 50 Hz mains hum (60 Hz if you are unlucky enough to be ruled by Mr Trump!).

    You can send the signal to the sound card on your PC, using that as an A/D converter. Then display the result using a Python script. That's all shown at http://www.swharden.com/wp/20160808diyecgwith1opamp/ . It's also presented on here as an Instructable, but I cannot find it just now. His circuit, by the way, is simpler using just a 741 Op Amp and seems to work quite well. He implements a low-pass filter in software (adjustable) to get rid of mains hum.

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  • Super Simple Electrocardiogram (ECG) Circuit

    There's an inconsistency here. If you build yourself an ECG, heart-monitoring machine, ie a kit of parts with wires to wrists and ankles, you all worry you might get electrocuted by your 5v mains PSU. But if you instead built say a radio or anything else powered by that same PSU, you would not be in the slightest concerned if you touched live wires during the construction process because its only 5v. But thats the same 5v, connected to your hands. Its either dangerous in both circuits or safe in both circuits - completely irrelevant that one happens to be measuring your heart.I suggest to you that this circuit is perfectly safe, unless your mains adaptor is faulty - then it is dangerous whatever the circuit you construct!The body has a high resistance and is immune to low voltages like ...see more »There's an inconsistency here. If you build yourself an ECG, heart-monitoring machine, ie a kit of parts with wires to wrists and ankles, you all worry you might get electrocuted by your 5v mains PSU. But if you instead built say a radio or anything else powered by that same PSU, you would not be in the slightest concerned if you touched live wires during the construction process because its only 5v. But thats the same 5v, connected to your hands. Its either dangerous in both circuits or safe in both circuits - completely irrelevant that one happens to be measuring your heart.I suggest to you that this circuit is perfectly safe, unless your mains adaptor is faulty - then it is dangerous whatever the circuit you construct!The body has a high resistance and is immune to low voltages like this. I am not in the slightest concerned to grab the terminals of a 12v car battery one in each hand.

    It's V1 to V6 actually - the electrodes placed across the left front of the chest wall.This circuit is in effect displaying Electrode 2 (left arm) (ie the heart as viewed from left shoulder - where the left arm joins the body!), using Electrode 1 as reference and Electrode 3 as a ground.So to view V1 to V6, simply move the Electrode 2 from left wrist to the desired place on chest wall and that will do the trick. Maybe not medically perfect, but close enough.

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  • iancarbarns commented on pinchan's instructable Use Your Tablet As Raspberry Pi Screen1 month ago
    Use Your Tablet As Raspberry Pi Screen

    You don't need a monitor. You should be able to look up the RPi's IP address by looking at your router's interface - in fact, better to look there anyway, because you will probably want to switch it to be a fixed local IP address which does not change day by day ...So you may as well look it up and make it fixed in the same step ...

    Rather than opening ports (which is inherently insecure) you can set up a free VPN service using Weave. See Raspberry Pi instructions at https://www.raspberrypi.org/documentation/remote-access/access-over-Internet/README.md

    The number after the colon in VNC-Viwer is NOT a port number, it is the monitor number on the Raspberry Pi's VNC-Server, usually it will be :1.In the picture in the Instructable, it does show :1, but the IP address shown only has 3 sections instead of 4!! (it says 192.168.16:1)Usually it will be 192.168.XXX.YYY:1 where XXX:YYY need to be substituted by your RPi's local IP address on your home network

    See https://www.raspberrypi.org/documentation/remote-access/vnc/ for better instructions how to achieve this, including over internet using Weave

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  • iancarbarns commented on pchretien's instructable The Fibonacci Clock7 months ago
    The Fibonacci Clock

    A great gift idea for my mathematical relatives!I made mine using Excel, entirely in software!

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