Need help with my final year project...

[karthikkrv85]

Thanks... i uploaded..

 

[karthikkrv85]

may i know what is the clock frequency for PIC?

 

[navarro_boyz]

if you are asking the external oscillator, it's 4MHZ.The internal oscillator is 1MHZ.

 

[karthikkrv85]

ok did you got the image and have got the output?

 

[navarro_boyz]

Yeah. I really get an output but it is very high pulse rate.

 

[karthikkrv85]

I think you have to reduce the no of DC pulses in the DC generator. and also verify the calculation if u have done anything in code.

 

[navarro_boyz]

The maximum heart rate should be 120 bpm according to Mr.Dogan Ibrahim since the cut off frequency of the filter is 2Hz.The first amp should have a gain just over 100 and the second amp will have a gain around 560.When i calculate manually, for the first amp gain is 122.95 and the second amp gain is 561K.Which value to take for the cutoff frequency?

 

[karthikkrv85]

The maximum heart rate should be 120 bpm according to Mr.Dogan Ibrahim since the cut off frequency of the filter is 2Hz.

Sorry i dont know about mr.dogan. May i know where did you found such details about cut off frequency? if you have any documents, please forward. May be i can go through and let u know

The first amp should have a gain just over 100 and the second amp will have a gain around 560.When i calculate manually, for the first amp gain is 122.95 and the second amp gain is 561K.Which value to take for the cutoff frequency?

I dont understand this part properly..

 

[navarro_boyz]

You can look at my post at the first page.There will be a pdf file with a link.Full information can be obtained from there.

 

[karthikkrv85]

hai.. i dont think the filter is related to the opamp gain. As per the explanation, you have to implement a low pass filter at the output of OP-amp section (output of 2nd opamp). And the circuit which they have shown u is without filter.

You can design the low pass filter using RC circuit with 2 HZ of cut off and then implement it.

 

[navarro_boyz]

Are you sure there is no low pass filter in the circuit.Have a look at this linkhttps://embedded-lab.com/blog/?p=1671

 

[be80be]

There a low pass filter That's what the 8.2k and 1M and 100n are making up nice find about the ground

here the low pass filter

 

[navarro_boyz]

So, that's mean my circuit has a low pass filter? I am confused now.What kind of circuit arrangement of op amp that i have in my circuit?

 

[be80be]

The op-amp is set up with one View attachment 60439 https://en.wikipedia.org/wiki/Low-pass_filter

 

[be80be]

What kind of circuit arrangement of op amp that i have in my circuit?

active low-pass filter

 

[navarro_boyz]

I get cutoff frequency of 1.59hz for the first amp and 2.834 hz for the second amp.So, what is meant by the cutoff frequency of the filter was chosen as 2hz?

 

[be80be]

It's more like this

The signal conditioning circuit consists of two identical active low pass filters with a cut-off frequency of about 2.5 Hz. This means the maximum measurable heart rate is about 150 bpm

I think if you reread the PDF in the files you posted He said do to noise he added lowpass filter of round 2 Hz But on the blog you post link to he shows the math and it's more like 2.34


But I don't get where they came up with them figures myself looks more like 1.5 hz would be in line.

 

[navarro_boyz]

I really need to know why the low pass filter is around 2hz.Btw, normally the vee of the op amp and the ground should not be connected together but in my circuit,the negative 9v is connected to the ground of the voltage regulator and the vee is connected to the ground.Therefore,is it a correct connection?If so, what is the explanation?

 

[be80be]

It's not 2hz it's more like 1.5 hz

 

[navarro_boyz]

How about my second question?