You can buy it for $8 COTS.
You clean up the QRS waveform with a one-shot then integrate to get rate.
----- Original Message -----
From: "Bob Camp" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Tuesday, February 19, 2013 8:23 PM
Subject: Re: [time-nuts] Off topic project sort of heart rate monitor
NEEDBEATS PRE MINUTE TO ANALOG VOLTAGE
Hi
The first layer to the onion is that the ECG signal is a bit complex.
There's also likely to be a bit of this and that on it.
How about taking the output of the instrument amp into the A/D port on a
cheap PIC? That would let you do some AGC and dynamic filtering. At even a
modest sample rate (say 10 KHz) the heart rate could be worked out in
software. I think I'd run a PWM out and drive an analog meter with it.
The nice thing about keeping it simple is being able to run it off a 9 volt
battery. That takes care of a *lot* of issues.
Bob
On Feb 19, 2013, at 7:58 PM, Paul Cianciolo <[email protected]> wrote:
Hello Folks,
I am working on a project intended to convert an analog ECG signal to a
voltage proportional the heart rate,
The actual electrodes instrumentation amp is pretty much working fine so
no worries there.
The problem is, and here is where the relationship to time nut comes in.
The signal output from the instrumentation amplifiers will be at a rate of
approx 60 BPM or pulses, up to perhaps 90 BPM.
The purpose of this apparatus is to print a rolling chart on the screen of
a computer of heart BPM and then try different technicues of meditaion
and calming technicues to lower my heart rate for short periods of time.
My first tthought was a frequency to voltage IC like the LM2907 or the
2917 but I get the impresiion from the data sheets that these chips will
not work at these very low 1 Hz applications,
Then I thought maybe one of the frequecy counters could be configured as a
rate meter and output a proportional voltage I need.
No luck here either.
Te latter components seem tobe somewhat time relatedand that is why I
posted here.\\
Thank you for reading this and for any suggestions you folks might offer.
PaulC
W1VLF
1Hxz
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