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Topic: Accepts 50-60Hz noise and reject all other signal (Read 870 times) previous topic - next topic

mudassir9999

I am working on a Heart rate measurement project where I am using AD8232 board from SparkFun this board is in Cardiac configuration and uses 3 electrodes at input (RA,LA and RLD). Here I want to use only two
 electrodes, I know it's mandatory to use RA and LA electrode, where as RLD is used to reject 50-60Hz AC noise.
I thought connecting the RLD to RA and LA will help... But It's rejecting the main signal.
I wanted to be tricky here, I want to use any of the two electrodes (RA or LA) and use a filter circuit at RLD, Where the filter circuit should reject all other signal but only accepts 50-60Hz noise.

Please help.
Thank you

bastiaang

Hi mudassir9999,

I have an idea how you can solve this. All you need is a Bandpass Filter. I prefer an active bandpass filter, but that is up to you. This link shows you how to create an bandpassfilter.

http://www.electronics-tutorials.ws/filter/filter_7.html

I have done some calcs on the first circuit on that page and these are my results:

R1 = 31.831 kOhm
C1 = 100 nF
R2 = 26.526 kOhm
C2 = 100 nF

R3 and R4 are not necessery because you dont need to have some gain.
So connect the inverting pin of the op amp to the output.

Hopefully this will help you.



MarkT

The trouble with mains interference is that it is not just the fundamental, there are harmonics, so
you really want steep constant phase notch filters at the fundamental and low harmonics for best results, which is
a job for a digital filter.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

arduinoaleman

Forget an Arduino solution.

You need an OP-Amp solution with a low pass filter circuit.

If your questions are not precise, nobody can help you.

dlloyd

Quote
Where the filter circuit should reject all other signal but only accepts 50-60Hz noise.
Noise? Wait a minute ... my heart rate is 55 - 60!   

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