[time-nuts] Off topic project sort of heart rate monitor NEED BEATS PRE MINUTE TO ANALOG VOLTAGE

Bob Camp lists at rtty.us
Wed Feb 20 07:02:16 EST 2013


Actually I have the 70's beat by a decade in terms of playing with home made ECG gear….


On Feb 20, 2013, at 2:39 AM, Ed Breya <eb at telight.com> wrote:

> If you only need cardiac pulse rate, an optical pulse-oximeter type interface - but without the oximetry part - would be much simpler than an ECG system, and it doesn't need galvanic connection. If you need more than that, then ECG methods should suffice.
> Back in the 1970s, there was a lot of interest in biofeedback and TM techniques, using ECG and EEG. Common feedback signals were sound and light related to the detected physiological signals. A chart display is a good visual feedback with dynamics too, and it records the events for further study, so you can investigate the QRST details and whatever else is interesting. Detecting and processing the signals is nearly trivial now with modern electronics - it wasn't even that hard back then. If you study what's transpired over the last forty years, you'll get a pretty good idea of the whole history of the field, and the technologies involved. Nowadays of course, the PC can take care of most of the processing and feedback/indicator functions.
> For a DIY, I'd recommend for each channel run the high-gain instrumentation amplifier into a V-F or FM converter to translate the signal into a workable frequency range like a few hundred Hz, then use a sound card and SW to post-process. Copy front-end interface ideas from the real stuff - professional medical equipment - to make sure it's safe to hook up to your own hide. If you don't need absolute details, you can AC-couple the physiological signals into the V-F process with appropriate time constants, to avoid the drift, and average in SW.
> I doubt that interest in this area has waned over the decades, so it's likely there are all kinds of cooler, newer stuff available off-shelf, so you may be able to find it ready to go - and even way beyond what you had in mind.
> Ed
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